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<book lang='en'>
<bookinfo>
<title>Frequently Asked Questions for &os;
&rel3.relx;, &rel2.relx;, and &rel.relx;</title>
<corpauthor>The &os; Documentation Project</corpauthor>
<copyright>
<year>1995</year>
<year>1996</year>
<year>1997</year>
<year>1998</year>
<year>1999</year>
<year>2000</year>
<year>2001</year>
<year>2002</year>
<year>2003</year>
<year>2004</year>
<year>2005</year>
<year>2006</year>
<year>2007</year>
<year>2008</year>
<year>2009</year>
<year>2010</year>
<year>2011</year>
<year>2012</year>
<year>2013</year>
<holder>The &os; Documentation Project</holder>
</copyright>
&legalnotice;
<legalnotice id="trademarks" role="trademarks">
&tm-attrib.freebsd;
&tm-attrib.adobe;
&tm-attrib.ibm;
&tm-attrib.ieee;
&tm-attrib.intel;
&tm-attrib.linux;
&tm-attrib.microsoft;
&tm-attrib.mips;
&tm-attrib.opengroup;
&tm-attrib.oracle;
&tm-attrib.sgi;
&tm-attrib.sparc;
&tm-attrib.sun;
&tm-attrib.general;
</legalnotice>
<releaseinfo>$FreeBSD$</releaseinfo>
<abstract>
<para>This is the FAQ for &os; versions
&rel3.relx;, &rel2.relx; and &rel.relx;.
All entries are assumed to be
relevant to &os; &rel3.relx; and later,
unless otherwise noted. If you are interested in helping with
this project, send email to the &a.doc;. The latest version of
this document is always available from the <ulink
url="http://www.FreeBSD.org/doc/en_US.ISO8859-1/books/faq/index.html">&os; website</ulink>.
It may also be downloaded as one large <ulink
url="book.html">HTML</ulink> file with HTTP or as a variety
of other formats from the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">&os; FTP
server</ulink>. You may also want to <ulink
url="&url.base;/search/index.html">Search the FAQ</ulink>.</para>
</abstract>
</bookinfo>
<chapter id="introduction">
<title>Introduction</title>
<para>Welcome to the &os;
&rel3.relx; -, &rel2.relx; - and &rel.relx; -
FAQ!</para>
<para>As is usual with Usenet FAQs, this document aims to cover the
most frequently asked questions concerning the &os; operating
system (and of course answer them!). Although originally intended
to reduce bandwidth and avoid the same old questions being asked
over and over again, FAQs have become recognized as valuable
information resources.</para>
<para>Every effort has been made to make this FAQ as informative as
possible; if you have any suggestions as to how it may be
improved, please feel free to mail them to the &a.doc;.</para>
<qandaset>
<qandaentry>
<question id="what-is-FreeBSD">
<para>What is &os;?</para>
</question>
<answer>
<para>&os; is a modern operating system for desktops,
laptops, servers, and embedded systems with
support for a large number of <ulink
url="http://www.FreeBSD.org/platforms/">platforms</ulink>.</para>
<para>It is based on U.C.
Berkeley's <quote>4.4BSD-Lite</quote> release, with some
<quote>4.4BSD-Lite2</quote> enhancements. It is also based
indirectly on William Jolitz's port of U.C. Berkeley's
<quote>Net/2</quote> to the &i386;, known as
<quote>386BSD</quote>, though very little of the 386BSD code
remains.</para>
<para>&os; is used by companies, Internet Service Providers,
researchers, computer professionals, students and home users
all over the world in their work, education and
recreation.</para>
<para>For more detailed information on &os;, please see the
<ulink
url="&url.books.handbook;/index.html">&os; Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="FreeBSD-goals">
<para>What is the goal of the &os; Project?</para>
</question>
<answer>
<para>The goal of the &os; Project is to provide a
stable and fast general purpose
operating system that may
be used for any purpose
without strings attached.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="bsd-license-restrictions">
<para>Does the &os; license have any restrictions?</para>
</question>
<answer>
<para>Yes. Those restrictions do not control how you use the
code, merely how you treat the &os; Project itself. If you
have serious license concerns, read the actual <ulink
url="http://www.FreeBSD.org/copyright/freebsd-license.html">license</ulink>.
For the simply curious, the license can be summarized like
this.</para>
<itemizedlist>
<listitem>
<para>Do not claim that you wrote this.</para>
</listitem>
<listitem>
<para>Do not sue us if it breaks.</para>
</listitem>
<listitem>
<para>Do not remove or modify the license.</para>
</listitem>
</itemizedlist>
<para>Many of us have a significant investment in the
project
and would certainly not mind a little financial
compensation now and then, but we definitely do not insist
on it. We believe that our first and foremost
<quote>mission</quote> is to provide code to any and all
comers, and for whatever purpose, so that the code gets
the
widest possible use and provides the widest possible
benefit. This, we believe, is one of the most
fundamental
goals of Free Software and one that we enthusiastically
support.</para>
<para>Code in our source tree which falls under the
<ulink
url="http://www.FreeBSD.org/copyright/COPYING">GNU General Public License (GPL)</ulink>
or <ulink
url="http://www.FreeBSD.org/copyright/COPYING.LIB">GNU Library General Public License (LGPL)</ulink>
comes with slightly more strings attached, though at least
on the side of enforced access rather than the usual
opposite. Due to the additional complexities that can
evolve in the commercial use of GPL software, we do,
however, endeavor to replace such software with submissions
under the more relaxed <ulink
url="http://www.FreeBSD.org/copyright/freebsd-license.html">&os; license</ulink>
whenever possible.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="replace-current-OS">
<para>Can &os; replace my current operating system?</para>
</question>
<answer>
<para>For most people, yes. But this question is not quite
that cut-and-dried.</para>
<para>Most people do not actually use an operating system.
They use applications. The applications are what really use
the operating system. &os; is designed to provide a robust
and full-featured environment for applications. It supports
a wide variety of web browsers, office suites, email
readers, graphics programs, programming environments,
network servers, and just about everything else you might
want. Most of these applications can be managed through the
<ulink
url="http://www.FreeBSD.org/ports/">Ports Collection</ulink>.</para>
<para>If you need to use an application that is only available
on one operating system, you simply cannot replace that
operating system. Chances are there is a very similar
application on &os;, however. If you want a solid office or
Internet server, a reliable workstation, or just the ability
to do your job without interruptions, &os; will almost
certainly do everything you need. Many computer users
across the world, including both novices and experienced
&unix; administrators, use &os; as their only desktop
operating system.</para>
<para>If you are migrating to &os; from some other &unix;
environment, you already know most of what you need to. If
your background is in graphic-driven operating systems such
as &windows; and &macos;, you may be interested in using
<ulink
url="http://www.pcbsd.org/">PC-BSD</ulink>, a &os; based
distribution, instead. If you have not used &unix; before
expect to invest
additional time learning the &unix; way of doing things.
This FAQ and the <ulink
url="&url.books.handbook;/index.html">&os; Handbook</ulink>
are excellent places to start.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="why-called-FreeBSD">
<para>Why is it called &os;?</para>
</question>
<answer>
<itemizedlist>
<listitem>
<para>It may be used free of charge, even by commercial
users.</para>
</listitem>
<listitem>
<para>Full source for the operating system is freely
available, and the minimum possible restrictions have
been placed upon its use, distribution and incorporation
into other work (commercial or non-commercial).</para>
</listitem>
<listitem>
<para>Anyone who has an improvement or bug fix is free to
submit their code and have it added to the source tree
(subject to one or two obvious provisions).</para>
</listitem>
</itemizedlist>
<para>It is worth pointing out that the word
<quote>free</quote> is being used in two ways here, one
meaning <quote>at no cost</quote>, the other meaning
<quote>you can do whatever you like</quote>. Apart from one
or two things you <emphasis>cannot</emphasis> do with the
&os; code, for example pretending you wrote it, you can
really do whatever you like with it.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="differences-to-other-bsds">
<para>What are the differences between &os; and NetBSD,
OpenBSD, and other open source BSD operating systems?</para>
</question>
<answer>
<para>James Howard wrote a good explanation of the history and
differences between the various projects,
called <ulink
url="http://www.freebsdworld.gr/freebsd/bsd-family-tree.html">The BSD Family Tree</ulink>
which goes a fair way to answering this question.
Some of the information is out of date, but the history
portion in particular remains accurate.</para>
<para>Most of the BSDs share patches and code, even today.
All of the BSDs have common ancestry.</para>
<para>The design goals of &os; are described in
<xref linkend="FreeBSD-goals"/>, above. The design goals
of the other most popular BSDs may be summarized as
follows:</para>
<itemizedlist>
<listitem>
<para>OpenBSD aims for operating system security above
all else. The OpenBSD team wrote &man.ssh.1; and
&man.pf.4;, which have both been ported to &os;.</para>
</listitem>
<listitem>
<para>NetBSD aims to be easily ported to other hardware
platforms.</para>
</listitem>
<listitem>
<para>DragonFlyBSD is a fork of &os; 4.8 that has
since developed many interesting features of its own,
including the HAMMER file system and support for
user-mode <quote>vkernels</quote>.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="latest-version">
<para>What is the latest version of &os;?</para>
</question>
<answer>
<para>At any point in the development of &os;, there can be
multiple parallel branches. &rel.relx; releases are
made from the &rel.stable; branch, and &rel2.relx;
releases are made from the &rel2.stable; branch.</para>
<para>Up until the release of 8.0, the
&rel3.relx; series was the one known as
<emphasis>-STABLE</emphasis>. However, as of 8.0, the
&rel3.relx; branch will be designated for
an <quote>extended support</quote> status and receive only
fixes for major problems, such as security-related fixes.
There will be no more releases made from the
&rel3.stable; branch, and it is considered a
<quote>legacy</quote> branch and most current work will only
become a part of &rel.stable; and &rel2.stable;.</para>
<para>Version <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/i386/&rel.current;-RELEASE/">&rel.current;</ulink>
is the latest release from the &rel.stable;
branch; it was released in &rel.current.date;. Version
<ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/&rel2.current;-RELEASE/">&rel2.current;</ulink>
is the latest release from the &rel2.stable;
branch; it was released in &rel2.current.date;.</para>
<para>Briefly, <emphasis>-STABLE</emphasis> is aimed at the
ISP, corporate user, or any user who wants stability and a
minimal number of changes compared to the new (and possibly
unstable) features of the latest
<emphasis>-CURRENT</emphasis> snapshot. Releases can come
from either branch, but <emphasis>-CURRENT</emphasis> should
only be used if you are prepared for its increased
volatility (relative to <emphasis>-STABLE</emphasis>, that
is).</para>
<para>Releases are made <link
linkend="release-freq">every few months</link>. While
many people stay more up-to-date with the &os; sources (see
the questions on <link
linkend="current">&os.current;</link> and <link
linkend="stable">&os.stable;</link>) than that, doing so
is more of a commitment, as the sources are a moving
target.</para>
<para>More information on &os; releases can be found on the
<ulink
url="http://www.FreeBSD.org/releng/index.html">Release Engineering page</ulink>
on the &os; Web site.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="current">
<para>What is <emphasis>&os;-CURRENT</emphasis>?</para>
</question>
<answer>
<para><ulink
url="&url.books.handbook;/current-stable.html#current">&os.current;</ulink>
is the development version of the operating system, which
will in due course become the new &os.stable; branch. As
such, it is really only of interest to developers working on
the system and die-hard hobbyists. See the <ulink
url="&url.books.handbook;/current-stable.html#current">relevant section</ulink>
in the <ulink
url="&url.books.handbook;/index.html">Handbook</ulink> for
details on running <emphasis>-CURRENT</emphasis>.</para>
<para>If you are not familiar with &os;
you should not use
&os.current;. This branch sometimes evolves quite quickly
and due to mistake can be un-buildable at times.
People that use &os.current; are expected to be able to
analyze, debug, and report problems.</para>
<para>&os; <ulink
url="&url.base;/snapshots/">snapshot</ulink>
releases are made based on the current state of the
<emphasis>-CURRENT</emphasis> and
<emphasis>-STABLE</emphasis> branches. The goals behind
each snapshot release are:</para>
<itemizedlist>
<listitem>
<para>To test the latest version of the installation
software.</para>
</listitem>
<listitem>
<para>To give people who would like to run
<emphasis>-CURRENT</emphasis> or
<emphasis>-STABLE</emphasis> but who do not have the
time or bandwidth to follow it on a day-to-day basis an
easy way of bootstrapping it onto their systems.</para>
</listitem>
<listitem>
<para>To preserve a fixed reference point for the code in
question, just in case we break something really badly
later. (Although Subversion normally prevents anything
horrible like this happening.)</para>
</listitem>
<listitem>
<para>To ensure that all new features and fixes in need of
testing have the greatest possible number of potential
testers.</para>
</listitem>
</itemizedlist>
<para>No claims are made that any
<emphasis>-CURRENT</emphasis> snapshot can be considered
<quote>production quality</quote> for any purpose. If you
want to run a stable and fully tested system, you will have
to stick to full releases, or use the
<emphasis>-STABLE</emphasis> snapshots.</para>
<para>Snapshot releases are directly available from <ulink
url="&url.base;/snapshots/">snapshot</ulink>.</para>
<para>Official snapshots are generated on a regular
basis for all actively developed branches.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="stable">
<para>What is the <emphasis>&os;-STABLE</emphasis>
concept?</para>
</question>
<answer>
<para>Back when &os; 2.0.5 was released, &os; development
branched in two. One branch was named <ulink
url="&url.books.handbook;/current-stable.html#stable">-STABLE</ulink>,
one <ulink
url="&url.books.handbook;/current-stable.html#current">-CURRENT</ulink>.
<emphasis>&os;-STABLE</emphasis> is intended for Internet
Service Providers and other commercial enterprises for whom
sudden shifts or experimental features are quite
undesirable. It receives only well-tested bug fixes and
other small incremental enhancements.
<emphasis>&os;-CURRENT</emphasis>, on the other hand, has
been one unbroken line since 2.0 was released, leading
towards &rel.current;-RELEASE and beyond. For more detailed
information on branches see <quote><ulink
url="&url.articles.releng;/release-proc.html#rel-branch">&os; Release Engineering: Creating the Release Branch</ulink></quote>,
the status of the branches and the upcoming release schedule
can be found on the <ulink
url="http://www.FreeBSD.org/releng">Release Engineering Information</ulink> page.</para>
<para>&rel.current;-STABLE is the actively developed
<emphasis>-STABLE</emphasis> branch. The latest release on
the &rel.current;-STABLE branch is &rel.current;-RELEASE,
which was released in &rel.current.date;.</para>
<para>The &rel.head; branch is the actively developed
<emphasis>-CURRENT</emphasis> branch toward the next
generation of &os;. See <link
linkend="current">What is &os;-CURRENT?</link> for more
information on this branch.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="release-freq">
<para>When are &os; releases made?</para>
</question>
<answer>
<para>The &a.re; releases a new major version of &os; about
every 18 months and a new minor version about every 8 months,
on average. Release dates are announced well in advance, so
that the people working on the system know when their
projects need to be finished and tested. A testing period
precedes each release, to ensure that the addition
of new features does not compromise the stability of the
release. Many users regard this caution as one of the best
things about &os;, even though waiting for all the latest
goodies to reach <emphasis>-STABLE</emphasis> can be a
little frustrating.</para>
<para>More information on the release engineering process
(including a schedule of upcoming releases) can be found on
the <ulink
url="http://www.FreeBSD.org/releng/index.html">release engineering</ulink>
pages on the &os; Web site.</para>
<para>For people who need or want a little more excitement,
binary snapshots are made daily as discussed above.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="responsible">
<para>Who is responsible for &os;?</para>
</question>
<answer>
<para>The key decisions concerning the &os; project, such as
the overall direction of the project and who is allowed to
add code to the source tree, are made by a <ulink
url="&url.base;/administration.html#t-core">core team</ulink> of
9 people. There is a much larger team of more than 350
<ulink
url="&url.articles.contributors;/article.html#staff-committers">committers</ulink>
who are authorized to make changes directly to the &os;
source tree.</para>
<para>However, most non-trivial changes are discussed in
advance in the <link linkend="mailing">mailing lists</link>,
and there are no restrictions on who may take part in the
discussion.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="where-get">
<para>Where can I get &os;?</para>
</question>
<answer>
<para>Every significant release of &os; is available via
anonymous FTP from the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/"> &os; FTP site</ulink>:</para>
<itemizedlist>
<listitem>
<para>The latest &rel.stable; release, &rel.current;-RELEASE
can be found in the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/i386/&rel.current;-RELEASE/">&rel.current;-RELEASE directory</ulink>.</para>
</listitem>
<listitem>
<para><ulink url="&url.base;/snapshots/"> Snapshot</ulink>
releases are made monthly for the <link
linkend="current">-CURRENT</link> and <link
linkend="stable">-STABLE</link> branch, these being of
service purely to bleeding-edge testers and
developers.</para>
</listitem>
<listitem>
<para>The latest &rel2.stable; release, &rel2.current;-RELEASE
can be found in the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/&rel2.current;-RELEASE/">&rel2.current;-RELEASE directory</ulink>.</para>
</listitem>
</itemizedlist>
<para>Information about obtaining &os; on CD, DVD, and other
media can be found in <ulink
url="&url.books.handbook;/mirrors.html">the Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="access-pr">
<para>How do I access the Problem Report database?</para>
</question>
<answer>
<para>The Problem Report database of all user change requests
may be queried by using our web-based PR <ulink
url="http://www.FreeBSD.org/cgi/query-pr.cgi?query">query</ulink>
interface.</para>
<para>The &man.send-pr.1; command can be used to submit
problem reports and change requests via electronic mail.
Alternatively, the <ulink
url="http://www.freebsd.org/send-pr.html">web-based problem report submission interface</ulink>
can be used to submit problem reports through a web
browser.</para>
<para>Before submitting a problem report, please read <ulink
url="&url.articles.problem-reports;/article.html">Writing &os; Problem Reports</ulink>,
an article on how to write good problem reports.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="support">
<title>Documentation and Support</title>
<qandaset>
<qandaentry>
<question id="books">
<para>What good books are there about &os;?</para>
</question>
<answer>
<para>The project produces a wide range of documentation,
available online from this link: <ulink
url="http://www.FreeBSD.org/docs.html"></ulink>. In addition, <link
linkend="bibliography">the Bibliography</link> at the end of this
FAQ, and <ulink
url="&url.books.handbook;/bibliography.html">the one in the Handbook</ulink>
reference other recommended books.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="doc-formats">
<para>Is the documentation available in other formats, such as
plain text (ASCII), or &postscript;?</para>
</question>
<answer>
<para>Yes. The documentation is available in a number of
different formats and compression schemes on the &os; FTP
site, in the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/">/pub/FreeBSD/doc/</ulink>
directory.</para>
<para>The documentation is categorized in a number of
different ways. These include:</para>
<itemizedlist>
<listitem>
<para>The document's name, such as <literal>faq</literal>,
or <literal>handbook</literal>.</para>
</listitem>
<listitem>
<para>The document's language and encoding. These are
based on the locale names you will find under
<filename class="directory">/usr/share/locale</filename> on your &os;
system. The current languages and encodings that we
have for documentation are as follows:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>Name</entry>
<entry>Meaning</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>en_US.ISO8859-1</literal></entry>
<entry>English (United States)</entry>
</row>
<row>
<entry><literal>bn_BD.ISO10646-1</literal></entry>
<entry>Bengali or Bangla (Bangladesh)</entry>
</row>
<row>
<entry><literal>da_DK.ISO8859-1</literal></entry>
<entry>Danish (Denmark)</entry>
</row>
<row>
<entry><literal>de_DE.ISO8859-1</literal></entry>
<entry>German (Germany)</entry>
</row>
<row>
<entry><literal>el_GR.ISO8859-7</literal></entry>
<entry>Greek (Greece)</entry>
</row>
<row>
<entry><literal>es_ES.ISO8859-1</literal></entry>
<entry>Spanish (Spain)</entry>
</row>
<row>
<entry><literal>fr_FR.ISO8859-1</literal></entry>
<entry>French (France)</entry>
</row>
<row>
<entry><literal>hu_HU.ISO8859-2</literal></entry>
<entry>Hungarian (Hungary)</entry>
</row>
<row>
<entry><literal>it_IT.ISO8859-15</literal></entry>
<entry>Italian (Italy)</entry>
</row>
<row>
<entry><literal>ja_JP.eucJP</literal></entry>
<entry>Japanese (Japan, EUC encoding)</entry>
</row>
<row>
<entry><literal>mn_MN.UTF-8</literal></entry>
<entry>Mongolian (Mongolia, UTF-8 encoding)</entry>
</row>
<row>
<entry><literal>nl_NL.ISO8859-1</literal></entry>
<entry>Dutch (Netherlands)</entry>
</row>
<row>
<entry><literal>no_NO.ISO8859-1</literal></entry>
<entry>Norwegian (Norway)</entry>
</row>
<row>
<entry><literal>pl_PL.ISO8859-2</literal></entry>
<entry>Polish (Poland)</entry>
</row>
<row>
<entry><literal>pt_BR.ISO8859-1</literal></entry>
<entry>Portuguese (Brazil)</entry>
</row>
<row>
<entry><literal>ru_RU.KOI8-R</literal></entry>
<entry>Russian (Russia, KOI8-R encoding)</entry>
</row>
<row>
<entry><literal>sr_YU.ISO8859-2</literal></entry>
<entry>Serbian (Serbia)</entry>
</row>
<row>
<entry><literal>tr_TR.ISO8859-9</literal></entry>
<entry>Turkish (Turkey)</entry>
</row>
<row>
<entry><literal>zh_CN.GB2312</literal></entry>
<entry>Simplified Chinese (China, GB2312
encoding)</entry>
</row>
<row>
<entry><literal>zh_TW.Big5</literal></entry>
<entry>Traditional Chinese (Taiwan, Big5 encoding)</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<note>
<para>Some documents may not be available in all
languages.</para>
</note>
</listitem>
<listitem>
<para>The document's format. We produce the documentation
in a number of different output formats. Each format
has its own advantages and disadvantages. Some formats
are better suited for online reading, while others are
meant to be aesthetically pleasing when printed on
paper. Having the documentation available in any of
these formats ensures that our readers will be able to
read the parts they are interested in, either on their
monitor, or on paper after printing the documents. The
currently available formats are:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>Format</entry>
<entry>Meaning</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>html-split</literal></entry>
<entry>A collection of small, linked, HTML
files.</entry>
</row>
<row>
<entry><literal>html</literal></entry>
<entry>One large HTML file containing the entire
document</entry>
</row>
<row>
<entry><literal>pdf</literal></entry>
<entry>Adobe's Portable Document Format</entry>
</row>
<row>
<entry><literal>ps</literal></entry>
<entry>&postscript;</entry>
</row>
<row>
<entry><literal>rtf</literal></entry>
<entry>Microsoft's Rich Text Format</entry>
</row>
<row>
<entry><literal>txt</literal></entry>
<entry>Plain text</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<note>
<para>Page numbers are not automatically updated when
loading Rich Text Format into Word. Press <keycombo
action="simul"><keycap>Ctrl</keycap><keycap>A</keycap></keycombo>,
<keycombo
action="simul"><keycap>Ctrl</keycap><keycap>End</keycap></keycombo>,
<keycap>F9</keycap> after loading the document, to
update the page numbers.</para>
</note>
</listitem>
<listitem>
<para>The compression and packaging scheme.</para>
<orderedlist>
<listitem>
<para>Where the format is
<literal>html-split</literal>, the files are bundled
up using &man.tar.1;. The resulting
<filename>.tar</filename> file is then compressed
using the compression schemes detailed in the next
point.</para>
</listitem>
<listitem>
<para>All the other formats generate one file, called
<filename><replaceable>type</replaceable>.<replaceable>format</replaceable></filename>
(i.e., <filename>article.pdf</filename>,
<filename>book.html</filename>, and so on).</para>
<para>These files are then compressed using either
the <literal>zip</literal> or
<literal>bz2</literal> compression schemes.
&man.tar.1; can be used to uncompress these
files.</para>
<para>So the &postscript; version of the Handbook,
compressed using <literal>bzip2</literal> will be stored in a file
called <filename>book.ps.bz2</filename> in the
<filename class="directory">handbook/</filename> directory.</para>
</listitem>
</orderedlist>
</listitem>
</itemizedlist>
<para>After choosing the format and compression mechanism that
you want to download, you will have to download the compressed
files yourself, uncompress them, and then copy the
appropriate documents into place.</para>
<para>For example, the split HTML version of the FAQ,
compressed using &man.bzip2.1;, can be found in
<filename>doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2</filename>
To download and uncompress that file you would have
to do this:</para>
<screen>&prompt.root; <userinput>fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/en_US.ISO8859-1/books/faq/book.html-split.tar.bz2</userinput>
&prompt.root; <userinput>tar xvf book.html-split.tar.bz2</userinput></screen>
<para>If the file is compressed,
<application>tar</application> will automatically
detect the appropriate format and decompress it correctly.
You will be left with a collection of
<filename>.html</filename> files. The main one is called
<filename>index.html</filename>, which will contain the
table of contents, introductory material, and links to the
other parts of the document. You can then copy or move
these to their final location as necessary.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="mailing">
<para>Where do I find info on the &os; mailing lists?
What &os; news groups are available?</para>
</question>
<answer>
<para>You can find full information in the <ulink
url="&url.books.handbook;/eresources.html#eresources-mail">Handbook entry on mailing-lists</ulink>
and the <ulink
url="&url.books.handbook;/eresources-news.html">Handbook entry on newsgroups</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="irc">
<para>Are there &os; IRC (Internet Relay Chat)
channels?</para>
</question>
<answer>
<para>Yes, most major IRC networks host a &os; chat
channel:</para>
<itemizedlist>
<listitem>
<para>Channel <literal>#FreeBSD</literal> on <ulink
url="http://www.efnet.org/index.php">EFNet</ulink> is
a &os; forum, but do not go there for tech support or
try to get folks there to help you avoid the pain of
reading manual pages or doing your own research. It is
a chat channel, first and foremost, and topics there are
just as likely to involve sex, sports or nuclear weapons
as they are &os;. You Have Been Warned! Available at
server <hostid>irc.efnet.org</hostid>.</para>
</listitem>
<listitem>
<para>Channel <literal>#FreeBSDhelp</literal> on <ulink
url="http://www.efnet.org/index.php">EFNet</ulink> is
a channel dedicated to helping &os; users. They are
much more sympathetic to questions than
<literal>#FreeBSD</literal> is.</para>
</listitem>
<listitem>
<para>Channel <literal>##FreeBSD</literal> on <ulink
url="http://freenode.net/">Freenode</ulink> is a
general help channel with many users at any time.
The conversations have been known to run off-topic for a
while, but priority is given to users with &os;
questions. We are good about helping you understand the
basics, referring to the Handbook whenever possible, and
directing you where to learn more about the topic you
need help with. We are a primarily English speaking
channel, though we have users from all over the world.
If you would like to speak in your native language, try
to ask the question in English and then relocate to
another channel
<literal>##freebsd-<replaceable>lang</replaceable></literal>
as appropriate.</para>
</listitem>
<listitem>
<para>Channel <literal>#FreeBSD</literal> on <ulink
url="http://www.dal.net/">DALNET</ulink> is available at
<hostid>irc.dal.net</hostid> in the US and
<hostid>irc.eu.dal.net</hostid> in Europe.</para>
</listitem>
<listitem>
<para>Channel <literal>#FreeBSD</literal> on <ulink
url="http://www.undernet.org/">UNDERNET</ulink> is
available at <hostid>us.undernet.org</hostid> in the US
and <hostid>eu.undernet.org</hostid> in Europe. Since
it is a help channel, be prepared to read the documents
you are referred to.</para>
</listitem>
<listitem>
<para>Channel <literal>#FreeBSD</literal> on
<ulink url="http://www.rusnet.org.ru/">RUSNET</ulink>
is a russian-language oriented channel dedicated
to helping &os; users. This is also good place
for non-technical discussions.</para>
</listitem>
<listitem>
<para>Channel <literal>#bsdchat</literal> on <ulink
url="http://freenode.net/">Freenode</ulink> is a
Traditional-Chinese (UTF-8 encoding) language oriented
channel dedicated to helping &os; users. This is also
good place for non-technical discussions.</para>
</listitem>
</itemizedlist>
<para>The &os; wiki has a <ulink
url="http://wiki.freebsd.org/IrcChannels">good list</ulink>
of IRC channels.</para>
<para>Each of these channels are distinct and are not
connected to each other. Their chat styles also differ, so
you may need to try each to find one suited to your chat
style. As with <emphasis>all</emphasis> types of IRC
traffic, if you are easily offended or cannot deal with lots
of young people (and more than a few older ones) doing the
verbal equivalent of jello wrestling, do not even bother
with it.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="forums">
<para>Are there any web based forums to discuss &os;?</para>
</question>
<answer>
<para>The official &os; forums are located at <ulink
url="http://forums.FreeBSD.org/">http://forums.FreeBSD.org/</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="training">
<para>Where can I get commercial &os; training and
support?</para>
</question>
<answer>
<para><ulink
url="http://www.ixsystems.com">iXsystems, Inc.</ulink>,
parent company of the <ulink
url="http://www.freebsdmall.com/">&os; Mall</ulink>,
provides commercial &os; and PC-BSD software <ulink
url="http://www.ixsystems.com/bsdsupport">support</ulink>,
in addition to &os; development and tuning solutions.</para>
<para>BSD Certification Group, Inc. provides system
administration certifications for DragonFly BSD, &os;, NetBSD,
OpenBSD. If you are interested in them, visit <ulink
url="http://www.BSDCertification.org">their site</ulink>.</para>
<para>Any other organizations providing training and support
should contact the Project to be listed here.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="install">
<chapterinfo>
<author>
<firstname>Nik</firstname>
<surname>Clayton</surname>
<affiliation>
<address><email>nik@FreeBSD.org</email></address>
</affiliation>
</author>
</chapterinfo>
<title>Installation</title>
<qandaset>
<qandaentry>
<question id="which-architecture">
<para>Which platform should I download? I have a 64
bit capable &intel; CPU,
but I only see <literal>amd64</literal>.</para>
</question>
<answer>
<para>&arch.amd64; is the term &os; uses for 64-bit
compatible x86 architectures. Most modern computers
should use &arch.amd64;. Older hardware should use
&arch.i386;. If you are installing on a
non-x86-compatible architecture select the platform
which best matches the architecture you are
using.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="floppy-download">
<para>Which file do I download to get &os;?</para>
</question>
<answer>
<para>On the
<ulink url="http://www.freebsd.org/where.html">Getting &os;</ulink>
page select <literal>[iso]</literal> next to the
architecture you want to use.</para>
<para>Any of the following can be used:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>file</entry>
<entry>description</entry>
</row>
</thead>
<tbody>
<row>
<entry><filename>disc1.iso</filename></entry>
<entry>Contains enough to install &os; and
a minimal set of packages.</entry>
</row>
<row>
<entry><filename>dvd1.iso</filename></entry>
<entry>Similar to <filename>disc1.iso</filename>
but with additional packages.</entry>
</row>
<row>
<entry><filename>memstick.img</filename></entry>
<entry>A bootable image sufficient for copying to a
USB stick.</entry>
</row>
<row>
<entry><filename>bootonly.iso</filename></entry>
<entry>A minimal image that requires network
access during installation to completely
install &os;.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>&arch.pc98; users require these floppy images:
<filename>floppies/boot.flp</filename>,
<filename>floppies/kern1.flp</filename>,
<filename>floppies/kern2.flp</filename>, and
<filename>floppies/mfsroot1.flp</filename>. These images
need
to be copied onto floppies by tools like
&man.dd.1;.</para>
<para>Full instructions on this procedure and a little bit
more about installation issues in general can be found in
the <ulink
url="&url.books.handbook;/install.html">Handbook entry on installing &os;</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="floppy-image-too-large">
<para>What do I do if the images do not fit on a
single disk?</para>
</question>
<answer>
<para>Common mistakes when preparing the boot media
are:</para>
<itemizedlist>
<listitem>
<para>Not downloading the image in
<emphasis>binary</emphasis> mode when using
<acronym>FTP</acronym>.</para>
<para>Some FTP clients default their transfer mode to
<emphasis>ascii</emphasis> and attempt to change any
end-of-line characters received to match the conventions
used by the client's system. This will almost
invariably corrupt the boot image. Check the SHA-256
of
the downloaded boot image: if it is not
<emphasis>exactly</emphasis> that on the server, then
the download process is suspect.</para>
<para>To workaround: type <emphasis>binary</emphasis> at
the FTP command prompt after getting connected to the
server and before starting the download of the
image.</para>
</listitem>
<listitem>
<para>Using the DOS <command>copy</command> command (or
equivalent GUI tool) to transfer the boot image to
floppy.</para>
<para>Programs like <command>copy</command> will not work
as the boot image has been created to be booted into
directly. The image has the complete content of the
floppy, track for track, and is not meant to be placed
on the floppy as a regular file. You have to transfer
it to the floppy <quote>raw</quote>, using the low-level
tools (e.g., <command>fdimage</command> or
<command>rawrite</command>) described in the <ulink
url="&url.books.handbook;/install.html">installation guide to &os;</ulink>.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="install-instructions-location">
<para>Where are the instructions for installing &os;?</para>
</question>
<answer>
<para>Installation instructions for versions since
&os; 9.0 can be found at <ulink
url="&url.books.handbook;/bsdinstall.html">Handbook entry on installing &os;</ulink>.
Older instructions can be found in the <ulink
url="&url.books.handbook;/install.html">legacy entry on installing &os;</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="need-to-run">
<para>What do I need to run &os;?</para>
</question>
<answer>
<para>For &os; you will need a 486 or better PC, with
64 MB or more of RAM and at least 1 GB of hard
disk space.</para>
<para>See also <xref linkend="hardware"/>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="custom-boot-floppy">
<para>How can I make my own custom release or install disk?</para>
</question>
<answer>
<para>Customized &os; installation media can be created by
building a custom release. Follow the instructions in the
<ulink
url="&url.articles.releng;/article.html">Release Engineering</ulink>
article.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="windows-coexist">
<para>Can &windows; co-exist with &os;?</para>
</question>
<answer>
<para>If &windows; is installed first, then yes.
&os;'s boot manager
will then manage to boot &windows; and &os;. If you install
&windows; second, it will boorishly overwrite your boot
manager without even asking. If that happens, see the next
section.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="bootmanager-restore">
<para>Another operating system destroyed my Boot Manager. How
do I get it back?</para>
</question>
<answer>
<para>This depends on what boot manager you have installed.
The &os; boot selection menu (likely what you are using
if you end up in this situation) can be reinstalled using
&man.boot0cfg.8;. For example, to restore the boot menu
onto the disk <replaceable>ada0</replaceable>:</para>
<screen>&prompt.root; <userinput>boot0cfg -B ada0</userinput></screen>
<para>The non-interactive MBR bootloader can be installed using
&man.gpart.8;:</para>
<screen>&prompt.root; <userinput>gpart bootcode -b /boot/mbr ada0</userinput></screen>
<para>For more complex situations, including GPT disks, see &man.gpart.8;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="no-install-cdrom">
<para>I booted from my ATAPI CD-ROM, but the install program
says no CD-ROM is found. Where did it go?</para>
</question>
<answer>
<para>The usual cause of this problem is a mis-configured
CD-ROM drive. Many PCs now ship with the CD-ROM as the slave
device on the secondary IDE controller, with no master
device on that controller. This is illegal according to the
ATAPI specification, but &windows; plays fast and loose with
the specification, and the BIOS ignores it when booting.
This is why the BIOS was able to see the CD-ROM to boot from
it, but why &os; cannot see it to complete the
install.</para>
<para>Reconfigure your system so that the CD-ROM is either the
master device on the IDE controller it is attached to, or
make sure that it is the slave on an IDE controller that
also has a master device.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="need-complete-sources">
<para>Do I need to install the source?</para>
</question>
<answer>
<para>In general, no. There is nothing in the base
system which requires the presence of the source to
operate. Some ports, like <filename
role="package">sysutils/lsof</filename>, will not build
unless the source is installed. In particular, if the
port builds a kernel module or directly operates on kernel
structures, the source must be installed.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="need-kernel">
<para>Do I need to build a kernel?</para>
</question>
<answer>
<para>Usually not. The supplied <literal>GENERIC</literal>
kernel contains the drivers an ordinary computer will
need. &man.freebsd-update.8;, the &os; binary upgrade
tool, cannot upgrade custom kernels, another reason
to stick with the <literal>GENERIC</literal> kernel when
possible. For computers with very limited RAM, such as
embedded systems, it may be worthwhile to build a
smaller custom kernel containing just the required
drivers.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="password-encryption">
<para>Should I use DES, Blowfish, or MD5 passwords and how do
I specify which form my users receive?</para>
</question>
<answer>
<para>&os; 7 and 8 use MD5 password hashing by
default. Recent versions
of &os; use <emphasis>SHA512</emphasis> by default.
These are
believed to be more secure than the traditional &unix;
password format, which used a scheme based on the
<emphasis>DES</emphasis> algorithm. DES passwords are still
available if you need to share your password file with
legacy operating systems which still use the less secure
password format. &os; also allows you to use the Blowfish
and MD5 password formats. Which password
format to use for new passwords is controlled by the
<literal>passwd_format</literal> login capability in
<filename>/etc/login.conf</filename>, which takes values of
<literal>des</literal>, <literal>blf</literal> (if these are
available) or <literal>md5</literal>. See the
&man.login.conf.5; manual page for more information about
login capabilities.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="panic-on-install-reboot">
<para>Why do I get a <errorname>panic: can't mount
root</errorname> error when rebooting the system after
installation?</para>
</question>
<answer>
<para>This error comes from confusion between the boot block's
and the kernel's understanding of the disk devices. The
error usually manifests on two-disk IDE systems, with the
hard disks arranged as the master or single device on
separate IDE controllers, with &os; installed on the
secondary IDE controller. The boot blocks think the system
is installed on <devicename>ad0</devicename> (the second
BIOS disk) while the kernel assigns the first disk on the
secondary controller device, <devicename>ad2</devicename>.
After the device probing, the kernel tries to mount what the
boot blocks think is the boot disk,
<devicename>ad0</devicename>, while it is really
<devicename>ad2</devicename>, and fails.</para>
<para>To fix the problem, do one of the following:</para>
<orderedlist>
<listitem>
<para>Reboot the system and hit <keycap>Enter</keycap> at
the <literal>Booting kernel in 10 seconds; hit [Enter]
to interrupt</literal> prompt. This will drop you into
the boot loader.</para>
<para>Then type
<userinput>set root_disk_unit="<replaceable>disk_number</replaceable>"</userinput>.
<replaceable>disk_number</replaceable> will be
<literal>0</literal> if &os; is installed on the master
drive on the first IDE controller, <literal>1</literal>
if it is installed on the slave on the first IDE
controller, <literal>2</literal> if it is installed on
the master of the second IDE controller, and
<literal>3</literal> if it is installed on the slave of
the second IDE controller.</para>
<para>Then type <userinput>boot</userinput>, and your
system should boot correctly.</para>
<para>To make this change permanent (i.e, so you do not
have to do this every time you reboot or turn on your
&os; machine), put the line
<userinput>root_disk_unit="<replaceable>disk_number</replaceable>"</userinput>
in <filename>/boot/loader.conf.local</filename>.</para>
</listitem>
<listitem>
<para>Move the &os; disk onto the primary IDE
controller, so the hard disks are consecutive.</para>
</listitem>
</orderedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="memory-limits">
<para>What are the limits for memory?</para>
</question>
<answer>
<para>Memory limits depend on the platform used. On a
standard &i386; install, the limit is 4 GB but more
memory can be supported through &man.pae.4;. See <link
linkend="memory-i386-over-4gb">instructions for using 4 GB or more memory on &i386;</link>.</para>
<para>&os;/pc98 has a limit of 4 GB memory, and PAE can
not be used with it. Other architectures supported by &os;
have much higher theoretical limits on maximum memory (many
terabytes).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ffs-limits">
<para>What are the limits for FFS file systems?</para>
</question>
<answer>
<para>For FFS file systems, the maximum theoretical limit is
8 TB (2 G blocks), or 16 TB for the default
block size of 8 KB. In practice, there is a soft limit
of 1 TB, but with modifications file systems with
4 TB are possible (and exist).</para>
<para>The maximum size of a single FFS file is approximately
1 G blocks, or 4 TB with a block size of
4 KB.</para>
<table>
<title>Maximum File Sizes</title>
<tgroup cols="3">
<thead>
<row>
<entry>FS Block Size</entry>
<entry>Works</entry>
<entry>Should Work</entry>
</row>
</thead>
<tbody>
<row>
<entry>4 KB</entry>
<entry>> 4 GB</entry>
<entry>4 TB - 1</entry>
</row>
<row>
<entry>8 KB</entry>
<entry>> 32 GB</entry>
<entry>32 TB - 1</entry>
</row>
<row>
<entry>16 KB</entry>
<entry>> 128 GB</entry>
<entry>32 TB - 1</entry>
</row>
<row>
<entry>32 KB</entry>
<entry>> 512 GB</entry>
<entry>64 TB - 1</entry>
</row>
<row>
<entry>64 KB</entry>
<entry>> 2048 GB</entry>
<entry>128 TB - 1</entry>
</row>
</tbody>
</tgroup>
</table>
<para>When the FS block size is 4 KB, triple indirect
blocks work and everything should be limited by the maximum FS
block number that can be represented using triple indirect
blocks (approx.
1024<superscript>3</superscript> + 1024<superscript>2</superscript> + 1024),
but everything is limited by a (wrong) limit of
1 G - 1 on FS block numbers. The limit on FS
block numbers should be 2 G - 1. There are
some bugs for FS block numbers near 2 G - 1,
but such block numbers are unreachable when the FS block
size is 4 KB.</para>
<para>For block sizes of 8 KB and larger, everything
should be limited by the 2 G - 1 limit on FS
block numbers, but is actually limited by the
1 G - 1 limit on FS block numbers. Using the
correct limit of 2 G - 1 blocks does cause
problems.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="archsw-readin-failed-error">
<para>Why do I get an error message,
<errorname>archsw.readin.failed</errorname> after compiling
and booting a new kernel?</para>
</question>
<answer>
<para>Because your world and kernel are out of sync. This is
not supported. Be sure you use <command>make <maketarget>buildworld</maketarget></command>
and <command>make <maketarget>buildkernel</maketarget></command>
to update your kernel.</para>
<para>You can boot by specifying the kernel directly at the
second stage, pressing any key when the <literal>|</literal>
shows up before loader is started.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="general-configuration-tool">
<para>Is there a tool to perform post-installation
configuration tasks?</para>
</question>
<answer>
<para>Yes, &rel.head.releng; users can set
<varname>WITH_BSDCONFIG</varname> in
<filename>/etc/src.conf</filename>. Users of &rel.relx;
and higher may also install
<filename role="package">sysutils/bsdconfig</filename>.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="hardware">
<title>Hardware Compatibility</title>
<sect1 id="compatibility-general">
<title>General</title>
<qandaset>
<qandaentry>
<question id="which-hardware-to-get">
<para>I want to get a piece of hardware for my &os; system.
Which model/brand/type is best?</para>
</question>
<answer>
<para>This is discussed continually on the &os; mailing
lists. Since hardware changes so quickly, however, we
expect this. We <emphasis>still</emphasis> strongly
recommend that you read through the Hardware Notes
for &os; <ulink
url="&rel.current.hardware;">&rel.current;</ulink> or
<ulink
url="&rel2.current.hardware;">&rel2.current;</ulink> and
search the mailing list <ulink
url="http://www.FreeBSD.org/search/#mailinglists">archives</ulink>
before asking about the latest and greatest hardware.
Chances are a discussion about the type of hardware you
are looking for took place just last week.</para>
<para>If you are looking for a laptop, check the &a.mobile;
archives. Otherwise, you probably want the archives for
the &a.questions;, or possibly a specific mailing list for
a particular hardware type.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="memory-upper-limitation">
<para>Does &os; support more than 4 GB of memory (RAM)?
More than 16 GB? More than 48 GB?</para>
</question>
<answer>
<para>Yes. &os; as an operating system generally supports
as much physical memory (RAM) as the platform it is running
on does. Keep in mind that different platforms have
different limits for memory; for example &i386; without
<acronym>PAE</acronym> supports at most 4 GB of
memory (and usually less than that because of PCI address
space) and &i386; with PAE supports at most 64 GB
memory. AMD64 platforms currently deployed support up to
1 TB of physical memory.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="memory-i386-over-4gb">
<para>Why does &os; report less than 4 GB memory when
installed on an &i386; machine?</para>
</question>
<answer>
<para>The total address space on &i386; machines is 32-bit,
meaning that at most 4 GB of memory is addressable (can
be accessed). Furthermore, some addresses in this range
are reserved by hardware for different purposes, for
example for using and controlling PCI devices, for
accessing video memory, and so on. Therefore, the total
amount of memory usable by the operating system for its
kernel and applications is limited to significantly less
than 4 GB. Usually, 3.2 GB to 3.7 GB is
the maximum usable physical memory in this
configuration.</para>
<para>To access more than 3.2 GB to 3.7 GB of
installed memory (meaning up to 4 GB but also more than
4 GB), a special tweak called <acronym>PAE</acronym>
must be used. PAE stands for Physical Address Extension
and is a way for 32-bit x86 CPUs to address more than
4 GB of memory. It remaps the memory that would
otherwise be overlaid by address reservations for
hardware devices above the 4 GB range and uses it as
additional physical memory (see &man.pae.4;). Using PAE
has some drawbacks; this mode of memory access is a little
bit slower than the normal (without PAE) mode and loadable
modules (see &man.kld.4;) are not supported. This means
all drivers must be compiled into the kernel.</para>
<para>The most common way to enable PAE is to build a new
kernel with the special ready-provided kernel configuration
file called <filename>PAE</filename>, which is already
configured to build a safe kernel. Note that some entries
in this kernel configuration file are too conservative and
some drivers marked as unready to be used with PAE are
actually usable. A rule of thumb is that if the driver is
usable on 64-bit architectures (like AMD64), it is also
usable with PAE. If you wish to create your own kernel
configuration file, you can enable PAE by adding the
following line to your configuration:</para>
<programlisting>options PAE</programlisting>
<para>PAE is not much used nowadays because most new x86
hardware also supports running in 64-bit mode, known as
AMD64 or &intel; 64. It has a much larger address
space and does not need such tweaks. &os; supports AMD64
and it is recommended that this version of &os; be used
instead of the &i386; version if 4 GB or more memory
is required.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-processors">
<title>Architectures and Processors</title>
<qandaset>
<qandaentry>
<question id="architectures">
<para>Does &os; support architectures other than the
x86?</para>
</question>
<answer>
<para>Yes. &os; divides support into multiple tiers.
Tier 1 architectures, such as i386 or amd64; are
fully supported. Tiers 2 and 3 are supported on a
if-possible basis. A full explanation of the tier
system is available in the
<ulink
url="&url.articles.committers-guide;/archs.html">Committer's Guide.</ulink></para>
<para>A complete list of supported architectures can be
found on the
<ulink
url="http://www.FreeBSD.org/platforms/">platforms page.</ulink></para>
</answer>
</qandaentry>
<qandaentry>
<question id="smp-support">
<para>Does &os; support Symmetric Multiprocessing
(SMP)?</para>
</question>
<answer>
<para>Symmetric multi-processor (SMP) systems are generally
supported by &os;, although in some cases, BIOS or
motherboard bugs may generate some problems.</para>
<para>&os; will take advantage of HyperThreading (HTT)
support on &intel; CPUs that support this feature. A kernel
with the <literal>options SMP</literal> feature enabled
will automatically detect the additional logical
processors.</para>
<para>&man.smp.4; has more details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="microcode">
<para>What is microcode?
How do I install &intel; CPU microcode updates?</para>
</question>
<answer>
<para>Microcode is a method of programmatically
implementating hardware level instructions. This allows
for CPU bugs to be fixed without replacing the on board chip.</para>
<para>Install <filename role="package">sysutils/devcpu-data</filename>,
then add:</para>
<programlisting>microcode_update_enable="YES"</programlisting>
<para>to <filename>/etc/rc.conf</filename></para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-drives">
<title>Hard Drives, Tape Drives, and CD and DVD Drives</title>
<qandaset>
<qandaentry>
<question id="supported-hard-drives">
<para>What kind of hard drives does &os; support?</para>
</question>
<answer>
<para>&os; supports EIDE, SATA, SCSI, and SAS drives (with a
compatible controller; see the next section), and all
drives using the original <quote>Western Digital</quote>
interface (MFM, RLL, ESDI, and of course IDE). A few ESDI
controllers that use proprietary interfaces may not work:
stick to WD1002/3/6/7 interfaces and clones.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="supported-scsi-controllers">
<para>Which SCSI or SAS controllers are supported?</para>
</question>
<answer>
<para>See the complete list in the Hardware Notes for &os;
<ulink url="&rel.current.hardware;">&rel.current;</ulink>
or <ulink
url="&rel2.current.hardware;">&rel2.current;</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="tape-support">
<para>What types of tape drives are supported?</para>
</question>
<answer>
<para>&os; supports SCSI and QIC-36 (with a QIC-02
interface). This includes 8-mm (aka Exabyte) and DAT
drives.</para>
<para>Some of the early 8-mm drives are not quite compatible
with SCSI-2, and may not work well with &os;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="tape-changer-support">
<para>Does &os; support tape changers?</para>
</question>
<answer>
<para>&os; supports SCSI changers using the &man.ch.4; device
and the &man.chio.1; command. The details of how you
actually control the changer can be found in the
&man.chio.1; manual page.</para>
<para>If you are not using <application>AMANDA</application>
or some other product that already understands changers,
remember that they only know how to move a tape from one
point to another, so you need to keep track of which slot a
tape is in, and which slot the tape currently in the drive
needs to go back to.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="supported-cdrom-drives">
<para>Which CD-ROM drives are supported by &os;?</para>
</question>
<answer>
<para>Any SCSI drive connected to a supported controller is
supported. Most ATAPI compatible IDE CD-ROMs are
supported.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="supported-cdrw-drives">
<para>Which CD-RW drives are supported by &os;?</para>
</question>
<answer>
<para>&os; supports any ATAPI-compatible IDE CD-R or CD-RW
drive. See &man.burncd.8; for details.</para>
<para>&os; also supports any SCSI CD-R or CD-RW drives.
Install and use <command>cdrecord</command>
from the ports or packages system, and make sure that you
have the <devicename>pass</devicename> device compiled in
your kernel.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-kbd-mice">
<title>Keyboards and Mice</title>
<qandaset>
<qandaentry>
<question id="moused">
<para>Is it possible to use a mouse in any way outside the X
Window system?</para>
</question>
<answer>
<para>If you are using the default console driver,
&man.syscons.4;, you can use a mouse pointer in text
consoles to cut & paste text. Run the mouse daemon,
&man.moused.8;, and turn on the mouse pointer in the
virtual console:</para>
<screen>&prompt.root; <userinput>moused -p /dev/<replaceable>xxxx</replaceable> -t <replaceable>yyyy</replaceable></userinput>
&prompt.root; <userinput>vidcontrol -m on</userinput></screen>
<para>Where <replaceable>xxxx</replaceable> is the mouse
device name and <replaceable>yyyy</replaceable> is a
protocol type for the mouse. The mouse daemon can
automatically determine the protocol type of most mice,
except old serial mice. Specify the
<literal>auto</literal> protocol to invoke automatic
detection. If automatic detection does not work, see the
&man.moused.8; manual page for a list of supported
protocol types.</para>
<para>If you have a PS/2 mouse, just add
<literal>moused_enable="YES"</literal> to
<filename>/etc/rc.conf</filename> to start the mouse
daemon at boot-time. Additionally, if you would like to
use the mouse daemon on all virtual terminals instead of
just the console, add
<literal>allscreens_flags="-m on"</literal> to
<filename>/etc/rc.conf</filename>.</para>
<para>When the mouse daemon is running, access to the mouse
must be coordinated between the mouse daemon and other
programs such as X Windows. Refer to the FAQ <link
linkend="x-and-moused">Why does my mouse not work with X?</link>
for more details on this issue.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="text-mode-cut-paste">
<para>How do I cut and paste text with a mouse in the text
console?</para>
</question>
<answer>
<para>It is not possible to remove data using the mouse.
However, it is possible to <quote>copy and
paste</quote>.
Once you get the mouse daemon running (see the
<link linkend="moused">previous question</link>)
hold down
button 1 (left button) and move the mouse to select a region
of text. Then, press button 2 (middle button) to paste
it at the text cursor. Pressing button 3 (right button)
will <quote>extend</quote> the selected region of
text.</para>
<para>If your mouse does not have a middle button, you may
wish to emulate one or remap buttons using mouse daemon
options. See the &man.moused.8; manual page for
details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="mouse-wheel-buttons">
<para>My mouse has a fancy wheel and buttons. Can I use
them in &os;?</para>
</question>
<answer>
<para>The answer is, unfortunately, <quote>It
depends</quote>. These mice with additional features
require specialized driver in most cases. Unless the
mouse device driver or the user program has specific
support for the mouse, it will act just like a standard
two, or three button mouse.</para>
<para>For the possible usage of wheels in the X Window
environment, refer to <link
linkend="x-and-wheel">that section</link>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="keyboard-delete-key">
<para>How do I use my delete key in <command>sh</command>
and <command>csh</command>?</para>
</question>
<answer>
<para>For the <application>Bourne Shell</application>, add
the following lines to your <filename>.shrc</filename>. See
&man.sh.1; and &man.editrc.5;.</para>
<programlisting>bind ^? ed-delete-next-char # for console
bind ^[[3~ ed-delete-next-char # for xterm</programlisting>
<para>For the <application>C Shell</application>, add the
following lines to your <filename>.cshrc</filename>. See
&man.csh.1;.</para>
<programlisting>bindkey ^? delete-char # for console
bindkey ^[[3~ delete-char # for xterm</programlisting>
<para>For more information, see <ulink
url="http://www.ibb.net/~anne/keyboard.html">this page</ulink>.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-networking">
<title>Networking</title>
<qandaset>
<qandaentry>
<question id="support-broadcom">
<para>Is there a native driver for the Broadcom 43xx
cards?</para>
</question>
<answer>
<para>Yes, many Broadcom 43xx cards are supported by the
&man.bwn.4; and &man.bwi.4; drivers.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-sound">
<title>Sound Devices</title>
<qandaset>
<qandaentry>
<question id="es1370-silent-pcm">
<para>Workarounds for no sound from my &man.pcm.4; sound
card?</para>
</question>
<answer>
<para>Some sound cards set their output volume to 0 at every
boot. Run the following command every time the machine
boots:</para>
<screen>&prompt.root; <userinput>mixer pcm 100 vol 100 cd 100</userinput></screen>
</answer>
</qandaentry>
</qandaset>
</sect1>
<sect1 id="compatibility-other">
<title>Other Hardware</title>
<qandaset>
<qandaentry>
<question id="power-management-support">
<para>Does &os; support power management on my
laptop?</para>
</question>
<answer>
<para>&os; supports the <acronym>ACPI</acronym>
features found in modern hardware. Further
information can be found in &man.acpi.4;.</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
</chapter>
<chapter id="troubleshoot">
<title>Troubleshooting</title>
<qandaset>
<qandaentry>
<question id="pae">
<para>Why is &os; finding the wrong amount of memory on &i386;
hardware?</para>
</question>
<answer>
<para>The most likely reason is the difference between
physical memory addresses and virtual addresses.</para>
<para>The convention for most PC hardware is to use the memory
area between 3.5 GB and 4 GB for a special purpose
(usually for PCI). This address space is used to access PCI
hardware. As a result real, physical memory can not be
accessed by that address space.</para>
<para>What happens to the memory that should appear in that
location is dependent on your hardware. Unfortunately, some
hardware does nothing and the ability to use that last
500 MB of RAM is entirely lost.</para>
<para>Luckily, most hardware remaps the memory to a higher
location so that it can still be used. However, this can
cause some confusion if you watch the boot messages.</para>
<para>On a 32-bit version of &os;, the memory appears
lost, since it will be remapped above 4 GB, which a
32-bit kernel is unable to access. In this case, the
solution is to build a PAE enabled kernel. See <link
linkend="memory-limits">the entry on memory limits</link>
and <link linkend="memory-upper-limitation">about different
memory limits on different platforms</link> for more
information.</para>
<para>On a 64-bit version of &os;, or when running a
PAE-enabled kernel, &os; will correctly detect and remap the
memory so it is usable. During boot, however, it may seem
as if &os; is detecting more memory than the system really
has, due to the described remapping. This is normal and the
available memory will be corrected as the boot process
completes.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="signal11">
<para>Why do my programs occasionally die with
<errorname>Signal 11</errorname> errors?</para>
</question>
<answer>
<para>Signal 11 errors are caused when your process has
attempted to access memory which the operating system has not
granted it access to. If something like this is happening
at seemingly random intervals then you need to start
investigating things very carefully.</para>
<para>These problems can usually be attributed to
either:</para>
<orderedlist>
<listitem>
<para>If the problem is occurring only in a specific
application that you are developing yourself it is
probably a bug in your code.</para>
</listitem>
<listitem>
<para>If it is a problem with part of the base &os;
system, it may also be buggy code, but more often than not
these problems are found and fixed long before us
general FAQ readers get to use these bits of code (that
is what -current is for).</para>
</listitem>
</orderedlist>
<para>In particular, a dead giveaway that this is
<emphasis>not</emphasis> a &os; bug is if you see the
problem when you are compiling a program, but the activity
that the compiler is carrying out changes each time.</para>
<para>For example, suppose you are running
<command>make <maketarget>buildworld</maketarget></command>,
and the compile fails while trying to compile
<filename>ls.c</filename> into <filename>ls.o</filename>.
If you then run
<command>make <maketarget>buildworld</maketarget></command>
again, and the compile fails in the same place then this is
a broken build — try updating your sources and try
again. If the compile fails elsewhere then this is almost
certainly hardware.</para>
<para>What you should do:</para>
<para>In the first case you can use a debugger e.g.,
&man.gdb.1; to find the point in the program which is
attempting to access a bogus address and then fix it.</para>
<para>In the second case you need to verify that it is not
your hardware at fault.</para>
<para>Common causes of this include:</para>
<orderedlist>
<listitem>
<para>Your hard disks might be overheating: Check the fans
in your case are still working, as your disk (and perhaps
other hardware might be overheating).</para>
</listitem>
<listitem>
<para>The processor running is overheating: This might be
because the processor has been overclocked, or the fan
on the processor might have died. In either case you
need to ensure that you have hardware running at what it
is specified to run at, at least while trying to solve
this problem (in other words, clock it back to the default
settings.)</para>
<para>If you are overclocking then note that it is far
cheaper to have a slow system than a fried system that
needs replacing! Also the wider community is not often
sympathetic to problems on overclocked systems, whether
you believe it is safe or not.</para>
</listitem>
<listitem>
<para>Dodgy memory: If you have multiple memory
SIMMS/DIMMS installed then pull them all out and try
running the machine with each SIMM or DIMM individually
and narrow the problem down to either the problematic
DIMM/SIMM or perhaps even a combination.</para>
</listitem>
<listitem>
<para>Over-optimistic Motherboard settings: In your BIOS
settings, and some motherboard jumpers you have options
to set various timings, mostly the defaults will be
sufficient, but sometimes, setting the wait states on
RAM too low, or setting the <quote>RAM Speed:
Turbo</quote> option, or similar in the BIOS will cause
strange behavior. A possible idea is to set to BIOS
defaults, but it might be worth noting down your
settings first!</para>
</listitem>
<listitem>
<para>Unclean or insufficient power to the motherboard.
If you have any unused I/O boards, hard disks, or CD-ROMs
in your system, try temporarily removing them or
disconnecting the power cable from them, to see if your
power supply can manage a smaller load. Or try another
power supply, preferably one with a little more power
(for instance, if your current power supply is rated at
250 Watts try one rated at 300 Watts).</para>
</listitem>
</orderedlist>
<para>You should also read the SIG11 FAQ (listed below) which
has excellent explanations of all these problems, albeit from
a &linux; viewpoint. It also discusses how memory testing
software or hardware can still pass faulty memory.</para>
<para>Finally, if none of this has helped it is possible that
you have just found a bug in &os;, and you should follow the
instructions to send a problem report.</para>
<para>There is an extensive FAQ on this at <ulink
url="http://www.bitwizard.nl/sig11/">the SIG11 problem FAQ</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="trap-12-panic">
<para>My system crashes with either <errorname>Fatal trap 12:
page fault in kernel mode</errorname>, or
<errorname>panic:</errorname>, and spits out a bunch of
information. What should I do?</para>
</question>
<answer>
<para>The &os; developers are very interested in these
errors, but need some more information than just the error
you see. Copy your full crash message. Then consult the
FAQ section on <link
linkend="kernel-panic-troubleshooting">kernel panics</link>,
build a debugging kernel, and get a backtrace. This might
sound difficult, but you do not need any programming skills;
you just have to follow the instructions.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="kmem-map-too-small">
<para>My system has more than 1 GB of RAM, and I'm
getting panics with <errorname>kmem_map too small</errorname>
messages. What is wrong?</para>
</question>
<answer>
<para>Normally, &os; determines a number of kernel parameters,
such as the maximum number of files that can be open
concurrently, from the amount of memory installed in the
system. On systems with one gigabyte of RAM or more, this
<quote>auto sizing</quote> mechanism may choose values that
are too high: while starting up, the kernel allocates
various tables and other structures that fill up most of the
available kernel memory. Later on, while the system is
running, the kernel has no more space left for dynamic
memory allocations, and panics.</para>
<para>Compile your own kernel, and add the
<option>VM_KMEM_SIZE_MAX</option> to your kernel
configuration file, increasing the maximum size to
400 MB (<option>options
VM_KMEM_SIZE_MAX=419430400</option>). 400 MB appears
to be sufficient for machines with up to 6 GB of
memory.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="panic-kmemmap-too-small">
<para>My system does not have 1 GB of RAM, and &os; still
panics with <errorname>kmem_map too
small</errorname>!</para>
</question>
<answer>
<para>The panic indicates that the system ran out of virtual
memory for network buffers (specifically, mbuf clusters).
You can increase the amount of VM available for mbuf
clusters by following the instructions in the <ulink
url="&url.books.handbook;/configtuning-kernel-limits.html#nmbclusters">Network Limits</ulink>
section of the Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="proc-table-full">
<para>Why do I get the error <errorname>maxproc limit
exceeded by uid %i, please see tuning(7) and
login.conf(5)</errorname>?</para>
</question>
<answer>
<para>The &os; kernel will only allow a certain number of
processes to exist at one time. The number is based on the
<varname>kern.maxusers</varname> &man.sysctl.8; variable.
<varname>kern.maxusers</varname> also affects various other
in-kernel limits, such as network buffers (see <link
linkend="panic-kmemmap-too-small">this</link> earlier
question). If your machine is heavily loaded, you probably
want to increase <varname>kern.maxusers</varname>. This
will increase these other system limits in addition to the
maximum number of processes.</para>
<para>To adjust your <varname>kern.maxusers</varname> value,
see the <ulink
url="&url.books.handbook;/configtuning-kernel-limits.html#kern-maxfiles">File/Process Limits</ulink>
section of the Handbook. (While that section refers to open
files, the same limits apply to processes.)</para>
<para>If your machine is lightly loaded, and you are simply
running a very large number of processes, you can adjust
this with the <varname>kern.maxproc</varname> tunable. If
this tunable needs adjustment it needs to be defined in
<filename>/boot/loader.conf</filename>. The tunable will
not get adjusted until the system is rebooted. For more
information about tuning tunables, see
&man.loader.conf.5;.
If these processes are being run by a single user, you will
also need to adjust <varname>kern.maxprocperuid</varname> to
be one less than your new <varname>kern.maxproc</varname>
value. (It must be at least one less because one system
program, &man.init.8;, must always be running.)</para>
</answer>
</qandaentry>
<qandaentry>
<question id="mail-loopback">
<para>Why does <application>sendmail</application> give me an
error reading <errorname>mail loops back to
myself</errorname>?</para>
</question>
<answer>
<para>You can find a detailed answer for this question in the
<ulink
url="&url.books.handbook;/mail-trouble.html#q26.5.2.">Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="remote-fullscreen">
<para>Why do full screen applications on remote machines
misbehave?</para>
</question>
<answer>
<para>The remote machine may be setting your terminal type to
something other than the <literal>cons25</literal> terminal
type required by the &os; console.</para>
<para>There are a number of possible work-arounds for this
problem:</para>
<itemizedlist>
<listitem>
<para>After logging on to the remote machine, set your
<envar>TERM</envar> shell variable to
<literal>ansi</literal> or <literal>sco</literal> if
the remote machine knows about these terminal
types.</para>
</listitem>
<listitem>
<para>Use a VT100 emulator like
<application>screen</application> at the &os; console.
<application>screen</application> offers you the
ability to run multiple concurrent sessions from one
terminal, and is a neat program in its own right.
Each <application>screen</application> window behaves
like a VT100 terminal, so the <envar>TERM</envar>
variable at the remote end should be set to
<literal>vt100</literal>.</para>
</listitem>
<listitem>
<para>Install the <literal>cons25</literal> terminal
database entry on the remote machine. The way to do
this depends on the operating system on the remote
machine. The system administration manuals for the
remote system should be able to help you here.</para>
</listitem>
<listitem>
<para>Fire up an X server at the &os; end and login to the
remote machine using an X based terminal emulator such
as <command>xterm</command> or <command>rxvt</command>.
The <envar>TERM</envar> variable at the remote host
should be set to <literal>xterm</literal> or
<literal>vt100</literal>.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="connection-delay">
<para>Why does it take so long to connect to my computer via
<command>ssh</command> or <command>telnet</command>?</para>
</question>
<answer>
<para>The symptom: there is a long delay between the time the
TCP connection is established and the time when the client
software asks for a password (or, in &man.telnet.1;'s case,
when a login prompt appears).</para>
<para>The problem: more likely than not, the delay is caused
by the server software trying to resolve the client's IP
address into a hostname. Many servers, including the
<application>Telnet</application> and
<application>SSH</application> servers that come with &os;,
do this to store the hostname
in a log file for future reference by the
administrator.</para>
<para>The remedy: if the problem occurs whenever you connect
from your computer (the client) to any server, the problem is
with the client; likewise, if the problem only occurs when
someone connects to your computer (the server) the problem
is with the server.</para>
<para>If the problem is with the client, the only remedy is to
fix the DNS so the server can resolve it. If this is on a
local network, consider it a server problem and keep
reading; conversely, if this is on the global Internet, you
will most likely need to contact your ISP and ask them to
fix it for you.</para>
<para>If the problem is with the server, and this is on a
local network, you need to configure the server to be able to
resolve address-to-hostname queries for your local address
range. See the &man.hosts.5; and &man.named.8; manual pages
for more information. If this is on the global Internet,
the problem may be that your server's resolver is not
functioning correctly. To check, try to look up another
host — say, <hostid>www.yahoo.com</hostid>. If it
does not work, that is your problem.</para>
<para>Following a fresh install of &os;, it is also possible
that domain and name server information is missing from
<filename>/etc/resolv.conf</filename>. This will often
cause a delay in <application>SSH</application>, as the
option <literal>UseDNS</literal> is set to
<literal>yes</literal> by default in
<filename>/etc/ssh/sshd_config</filename>.
If this is causing the
problem, you will either need to fill in the missing
information in <filename>/etc/resolv.conf</filename> or set
<literal>UseDNS</literal> to <literal>no</literal> in
<filename>sshd_config</filename> as a temporary
workaround.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="file-table-full">
<para>Why does <errorname>file: table is full</errorname> show
up repeatedly in &man.dmesg.8;?</para>
</question>
<answer>
<para>This error message indicates you have exhausted the
number of available file descriptors on your system. Please
see the <ulink
url="&url.books.handbook;/configtuning-kernel-limits.html#kern-maxfiles">kern.maxfiles</ulink>
section of the <ulink
url="&url.books.handbook;/configtuning-kernel-limits.html">Tuning Kernel Limits</ulink>
section of the Handbook for a discussion and
solution.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="computer-clock-skew">
<para>Why does the clock on my computer keep incorrect time?</para>
</question>
<answer>
<para>Your computer has two or more clocks, and &os; has
chosen to use the wrong one.</para>
<para>Run &man.dmesg.8;, and check for lines that contain
<literal>Timecounter</literal>. The one with the highest
quality value that &os; chose.</para>
<screen>&prompt.root; <userinput>dmesg | grep Timecounter</userinput>
Timecounter "i8254" frequency 1193182 Hz quality 0
Timecounter "ACPI-fast" frequency 3579545 Hz quality 1000
Timecounter "TSC" frequency 2998570050 Hz quality 800
Timecounters tick every 1.000 msec</screen>
<para>You can confirm this by checking the
<varname>kern.timecounter.hardware</varname>
&man.sysctl.3;.</para>
<screen>&prompt.root; <userinput>sysctl kern.timecounter.hardware</userinput>
kern.timecounter.hardware: ACPI-fast</screen>
<para>It may be a broken ACPI timer. The simplest solution is
to disable the ACPI timer in
<filename>/boot/loader.conf</filename>:</para>
<programlisting>debug.acpi.disabled="timer"</programlisting>
<para>Or the BIOS may modify the TSC clock—perhaps to
change the speed of the processor when running from batteries,
or going into a power saving mode, but &os; is unaware of
these adjustments, and appears to gain or lose time.</para>
<para>In this example, the <literal>i8254</literal> clock is
also available, and can be selected by writing its name to the
<varname>kern.timecounter.hardware</varname>
&man.sysctl.3;.</para>
<screen>&prompt.root; <userinput>sysctl kern.timecounter.hardware=i8254</userinput>
kern.timecounter.hardware: TSC -> i8254</screen>
<para>Your computer should now start keeping more accurate
time.</para>
<para>To have this change automatically run at boot time, add
the following line to
<filename>/etc/sysctl.conf</filename>:</para>
<programlisting>kern.timecounter.hardware=i8254</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="indefinite-wait-buffer">
<para>What does the error <errorname>swap_pager: indefinite
wait buffer:</errorname> mean?</para>
</question>
<answer>
<para>This means that a process is trying to page memory to
disk, and the page attempt has hung trying to access the
disk for more than 20 seconds. It might be caused by bad
blocks on the disk drive, disk wiring, cables, or any other
disk I/O-related hardware. If the drive itself is actually
bad, you will also see disk errors in
<filename>/var/log/messages</filename> and in the output of
<command>dmesg</command>. Otherwise, check your cables and
connections.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="lock-order-reversal">
<para>What is a <errorname>lock order
reversal</errorname>?</para>
</question>
<answer>
<para>An answer for this question can be found in the &os;
Glossary, see <ulink
url="&url.books.handbook;/freebsd-glossary.html#lor-glossary">LOR</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="called-with-non-sleepable-locks-held">
<para>What does <errorname>Called ... with the following
non-sleepable locks held</errorname> mean?</para>
</question>
<answer>
<para>This means that a function that may sleep was called
while a mutex (or other unsleepable) lock was held.</para>
<para>The reason this is an error is because mutexes are not
intended to be held for long periods of time; they are
supposed to only be held to maintain short periods of
synchronization. This programming contract allows device
drivers to use mutexes to synchronize with the rest of the
kernel during interrupts. Interrupts (under &os;) may not
sleep. Hence it is imperative that no subsystem in the
kernel block for an extended period while holding a
mutex.</para>
<para>To catch such errors, assertions may be added to the
kernel that interact with the &man.witness.4; subsystem to
emit a warning or fatal error (depending on the system
configuration) when a potentially blocking call is made
while holding a mutex.</para>
<para>In summary, such warnings are non-fatal, however with
unfortunate timing they could cause undesirable effects
ranging from a minor blip in the system's responsiveness to
a complete system lockup.</para>
<para>For additional information about locking in &os; see
&man.locking.9;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="touch-not-found">
<para>Why does
<maketarget>buildworld</maketarget>/<maketarget>installworld</maketarget>
die with the message <errorname>touch: not
found</errorname>?</para>
</question>
<answer>
<para>This error does not mean that the &man.touch.1; utility
is missing. The error is instead probably due to the dates
of the files being set sometime in the future. If your
CMOS-clock is set to local time you need to run the command
<command>adjkerntz -i</command> to adjust the kernel
clock when booting into single user mode.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="applications">
<title>User Applications</title>
<qandaset>
<qandaentry>
<question id="user-apps">
<para>So, where are all the user applications?</para>
</question>
<answer>
<para>Please take a look at <ulink
url="&url.base;/ports/index.html">the ports page</ulink>
for info on software packages ported to &os;. The list
currently tops &os.numports; and is growing daily, so come
back to check often or subscribe to the &a.announce; for
periodic updates on new entries.</para>
<para>Most ports should work on the
&rel3.relx;, &rel2.relx;, and &rel.relx; branches.
Each time a &os;
release is made, a snapshot of the ports tree at the time of
release in also included in the <filename class="directory">ports/</filename>
directory.</para>
<para>We also support the concept of a <quote>package</quote>,
essentially no more than a compressed binary distribution
with a little extra intelligence embedded in it for doing
whatever custom installation work is required. A package
can be installed and uninstalled again easily without having
to know the gory details of which files it includes.</para>
<para>Use
&man.pkg.add.1; on the specific package files
you are interested in installing. Package files can usually
be identified by their <filename>.tbz</filename> suffix and
CD-ROM distribution people will have a
<filename class="directory">packages/All</filename> directory on their CD
which contains such files. They can also be downloaded over
the net for various versions of &os; at the following
locations:</para>
<variablelist>
<varlistentry>
<term>for &rel3.relx; -RELEASE/&rel3.stable;</term>
<listitem>
<para><ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel3.packages;/">ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel3.packages;</ulink></para>
</listitem>
</varlistentry>
<varlistentry>
<term>for &rel2.relx; -RELEASE/&rel2.stable;</term>
<listitem>
<para><ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel2.packages;/">ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel2.packages;</ulink></para>
</listitem>
</varlistentry>
<varlistentry>
<term>for &rel.relx; -RELEASE/&rel.stable;</term>
<listitem>
<para><ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel.packages;/">ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/&rel.packages;</ulink></para>
</listitem>
</varlistentry>
</variablelist>
<para>or your nearest local mirror site.</para>
<para>Note that all ports may not be available as packages
since new ones are constantly being added. It is always a
good idea to check back periodically to see which packages
are available at the <ulink
url="ftp://ftp.FreeBSD.org/pub/FreeBSD/">ftp.FreeBSD.org</ulink>
master site.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="how-do-download-ports-tree">
<para>How do I download the Ports tree? Should I be using
SVN?</para>
</question>
<answer>
<para>Any of the methods listed here work:</para>
<itemizedlist>
<listitem>
<para>Use portsnap for most use cases.</para>
</listitem>
<listitem>
<para>Use SVN directly if you need custom patches
to the ports tree.</para>
</listitem>
<listitem>
<para>Use CTM if you prefer getting patches
by email (this is a rarer use case).</para>
</listitem>
</itemizedlist>
<para>Any other method should be considered a
legacy method. If you do not already use them,
do not start.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="java">
<para>Does &os; support &java;?</para>
</question>
<answer>
<para>Yes. Please see <ulink
url="&url.base;/java/index.html">http://www.FreeBSD.org/java/</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ports-4x">
<para>Why can I not build this port on my
&rel3.relx; -, &rel2.relx; -, or
&rel.relx; -STABLE machine?</para>
</question>
<answer>
<para>If you are running a &os; version that lags
significantly behind <emphasis>-CURRENT</emphasis> or
<emphasis>-STABLE</emphasis>, you may need to update your
Ports Collection; see the <ulink
url="&url.books.porters-handbook;/keeping-up.html">Keeping Up</ulink>
section of the Porter's Handbook for further information on
how to do this. If you are up to date, then someone might
have committed a change to the port which works for
<emphasis>-CURRENT</emphasis> but which broke the port for
<emphasis>-STABLE</emphasis>. Please submit a bug report on
this with the &man.send-pr.1; command, since the Ports
Collection is supposed to work for both the
<emphasis>-CURRENT</emphasis> and
<emphasis>-STABLE</emphasis> branches.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="make-index">
<para>I just tried to build <filename>INDEX</filename> using
<command>make <maketarget>index</maketarget></command>, and
it failed. Why?</para>
</question>
<answer>
<para>First, always make sure that you have a complete
up-to-date Ports Collection. Errors that affect building
<filename>INDEX</filename> from an up-to-date copy of the
Ports Collection are high-visibility and are thus almost
always fixed immediately.</para>
<para>There are rare cases where <filename>INDEX</filename>
will not build due to odd cases involving
<makevar>WITH_<replaceable>*</replaceable></makevar> or
<makevar>WITHOUT_<replaceable>*</replaceable></makevar>
variables being set in <filename>make.conf</filename>. If
you suspect that this is the case, please try to make
<filename>INDEX</filename> with those make variables turned
off before reporting it to &a.ports;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ports-update">
<para>I updated the sources, now how do I update my installed
ports?</para>
</question>
<answer>
<para>&os; does not include a port upgrading tool, but it does
have some tools to make the upgrade process somewhat easier.
You can also install additional tools to simplify port
handling, see the <ulink
url="&url.books.handbook;/ports-using.html">Upgrading Ports</ulink>
section in the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ports-major-upgrade">
<para>Do I need to recompile every port each time I perform a
major version update?</para>
</question>
<answer>
<para>By all means! While a recent system will run with
software compiled under an older release, you will end up with
things randomly crashing and failing to work once you start
installing other ports or updating a portion of what you
already have.</para>
<para>When the system is upgraded, various shared libraries,
loadable modules, and other parts of the system will be
replaced with newer versions. Applications linked against
the older versions may fail to start or, in other cases,
fail to function properly.</para>
<para>For more information, see <ulink
url="&url.books.handbook;/updating-upgrading-freebsdupdate.html#freebsdupdate-upgrade">the section on upgrades</ulink>
in the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ports-minor-upgrade">
<para>Do I need to recompile every port each time I perform a
minor version update?</para>
</question>
<answer>
<para>In general, no. &os; developers do their utmost to
guarantee binary compatibility across all releases with the
same major version number. Any exceptions will be
documented in the Release Notes, and advice given there
should be followed.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="minimal-sh">
<para>Why is <command>/bin/sh</command> so minimal? Why
does &os; not use <command>bash</command> or another
shell?</para>
</question>
<answer>
<para>Many people need to write shell scripts which will be
portable across many systems. That is why &posix;
specifies the shell and utility commands in great detail.
Most scripts are written in Bourne shell (&man.sh.1;), and
because several important programming interfaces
(&man.make.1;, &man.system.3;, &man.popen.3;, and
analogues in higher-level scripting languages like Perl
and Tcl) are specified to use the Bourne shell to
interpret commands. Because the Bourne shell is so often
and widely used, it is important for it to be quick to
start, be deterministic in its behavior, and have a small
memory footprint.</para>
<para>The existing implementation is our best effort at
meeting as many of these requirements simultaneously as we
can. To keep <command>/bin/sh</command> small,
we have not provided many of the convenience features that
other shells have. That is why other more
featureful shells like
<command>bash</command>, <command>scsh</command>,
&man.tcsh.1;, and <command>zsh</command> are available.
(You can
compare for yourself the memory utilization of all these
shells by looking at the <quote>VSZ</quote> and
<quote>RSS</quote> columns in a <command>ps
<option>-u</option></command> listing.)</para>
</answer>
</qandaentry>
<qandaentry>
<question id="midi-sound-files">
<para>How do I create audio CDs from my MIDI files?</para>
</question>
<answer>
<para>To create audio CDs from MIDI files, first install
<filename role="package">audio/timidity++</filename> from
ports then install manually the GUS patches set by Eric A.
Welsh, available at <ulink
url="http://alleg.sourceforge.net/digmid.html"></ulink>.
After <application>TiMidity++</application> has been installed
properly, MIDI files may be converted to WAV files with the
following command line:</para>
<screen>&prompt.user; <userinput>timidity -Ow -s 44100 -o <replaceable>/tmp/juke/01.wav</replaceable> <replaceable>01.mid</replaceable></userinput></screen>
<para>The WAV files can then be converted to other formats or
burned onto audio CDs, as described in the <ulink
url="&url.books.handbook;/creating-cds.html">&os; Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="officesuite">
<para>Where can I get an Office Suite for &os;?</para>
</question>
<answer>
<para>The open-source <application><ulink
url="http://www.openoffice.org">Apache OpenOffice</ulink></application>
and <application><ulink
url="http://www.libreoffice.org">LibreOffice</ulink></application>
office suites work natively on &os;.</para>
<para>&os; also includes a variety of text editors,
spreadsheets, and drawing programs in the Ports
Collection.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="database-systems">
<para>Are there any Database systems for &os;?</para>
</question>
<answer>
<para>Yes! See the <ulink
url="&url.base;/commercial/software_bycat.html#category_database">Commercial Vendors</ulink>
section of &os;'s Web site.</para>
<para>Also see the <ulink
url="&url.base;/ports/databases.html">Databases</ulink>
section of the Ports Collection.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="convert-back-from-pkgng">
<para>How can I convert from pkgng to the old package
tools?</para>
</question>
<answer>
<para>Short answer: it is not possible.</para>
<para>Longer answer: if you have made any changes using
<command>pkg</command> converting back is non-trivial and
requires lots of manual editing of internal package
database files. However, if you have just run
<command>pkg2ng</command> then you may remove
<filename>/var/db/pkg/local.sqlite</filename>
and extract
<filename>/var/backups/pkgdb.bak.tbz</filename>.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="kernelconfig">
<title>Kernel Configuration</title>
<qandaset>
<qandaentry>
<question id="make-kernel">
<para>I would like to customize my kernel. Is it
difficult?</para>
</question>
<answer>
<para>Not at all! Check out the <ulink
url="&url.books.handbook;/kernelconfig.html">kernel config section of the Handbook</ulink>.</para>
<note>
<para>The new <filename>kernel</filename> will be installed
to the <filename class="directory">/boot/kernel</filename> directory along
with its modules, while the old kernel and its modules
will be moved to the <filename class="directory">/boot/kernel.old</filename>
directory, so if you make a mistake the next time you play
with your configuration you can boot the previous version
of your kernel.</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="why-kernel-big">
<para>Why is my kernel so big?</para>
</question>
<answer>
<para><literal>GENERIC</literal> kernels shipped with &os;
and later are compiled in <emphasis>debug mode</emphasis>.
Kernels built in debug mode
contain many symbols in separate files that are used for
debugging, thus greatly increasing the size of
<filename class="directory">/boot/kernel/</filename>.
Note that there will be little or no performance loss
from running a debug kernel, and it is useful to keep one
around in case of a system panic.</para>
<para>However, if you are running low on disk space, there
are different options to reduce the size of <filename
class="directory">/boot/kernel/</filename>.</para>
<para>If you do not want the symbol files to be installed,
make sure you have the following line present in
<filename>/etc/src.conf</filename>:</para>
<programlisting>WITHOUT_KERNEL_SYMBOLS=yes</programlisting>
<para>For more information see &man.src.conf.5;.</para>
<para>If you do not want to build a debug kernel, make
sure that both of the following are true:</para>
<itemizedlist>
<listitem>
<para>You do not have a line in your kernel configuration
file that reads:</para>
<programlisting>makeoptions DEBUG=-g</programlisting>
</listitem>
<listitem>
<para>You are not running &man.config.8; with the
<option>-g</option> option.</para>
</listitem>
</itemizedlist>
<para>Either of the above settings will cause your kernel to
be built in debug mode. As long as you make sure you follow
the steps above, you can build your kernel normally.</para>
<para>If you want only the modules you use to be built
and installed, make sure you have a line like below in
<filename>/etc/make.conf</filename>:</para>
<programlisting>MODULES_OVERRIDE= <replaceable>accf_http ipfw</replaceable></programlisting>
<para>Replace <emphasis>accf_httpd ipfw</emphasis> with
a list of modules you need. Only these modules will be
built. This does not only reduce the size of the kernel
directory but also decreases the amount of time needed to
build your kernel. For more information see
<filename>/usr/share/examples/etc/make.conf</filename>.</para>
<para>You can also remove unneeded devices from your kernel
to further reduce the size. See
<xref linkend="make-kernel"/> for more information.</para>
<para>To put any of these options into effect you will have
to <ulink url="&url.books.handbook;/kernelconfig-building.html">build and install</ulink>
your new kernel.</para>
<para>Most kernels (<filename>/boot/kernel/kernel</filename>)
tend to be around 12 MB to 16 MB.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="generic-kernel-build-failure">
<para>Why does every kernel I try to build fail to compile,
even <filename>GENERIC</filename>?</para>
</question>
<answer>
<para>There are a number of possible causes for this problem.
They are, in no particular order:</para>
<itemizedlist>
<listitem>
<para>You are not using the
<command>make <maketarget>buildkernel</maketarget></command> and
<command>make <maketarget>installkernel</maketarget></command>
targets, and your source tree is different from the one
used to build the currently running system (e.g., you
are compiling &rel.current;-RELEASE on a
&rel2.current;-RELEASE system). If you are attempting
an upgrade, please read
<filename>/usr/src/UPDATING</filename>, paying
particular attention to the <quote>COMMON ITEMS</quote>
section at the end.</para>
</listitem>
<listitem>
<para>You are using the
<command>make <maketarget>buildkernel</maketarget></command>
and
<command>make <maketarget>installkernel</maketarget></command>
targets, but you failed to assert the completion of the
<command>make <maketarget>buildworld</maketarget></command>
target. The
<command>make <maketarget>buildkernel</maketarget></command>
target relies on files generated by the
<command>make <maketarget>buildworld</maketarget></command>
target to complete its job correctly.</para>
</listitem>
<listitem>
<para>Even if you are trying to build <link
linkend="stable">&os;-STABLE</link>, it is possible that
you fetched the source tree at a time when it was either
being modified, or broken for other reasons; only
releases are absolutely guaranteed to be buildable,
although <link linkend="stable">&os;-STABLE</link>
builds fine the majority of the time. If you have not
already done so, try re-fetching the source tree and see
if the problem goes away. Try using a different server
in case the one you are using is having problems.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="scheduler-in-use">
<para>How can I verify which scheduler is in use on a running
system?</para>
</question>
<answer>
<para>The name of the scheduler currently being used is
directly available as the value of the
<varname>kern.sched.name</varname> sysctl:</para>
<screen>&prompt.user; sysctl <replaceable>kern.sched.name</replaceable>
kern.sched.name: ULE</screen>
</answer>
</qandaentry>
<qandaentry>
<question id="scheduler-kern-quantum">
<para>What is <varname>kern.sched.quantum</varname>?</para>
</question>
<answer>
<para><varname>kern.sched.quantum</varname> is the maximum
number of ticks a process can run without being preempted
in the 4BSD scheduler.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="disks">
<title>Disks, File Systems, and Boot Loaders</title>
<qandaset>
<qandaentry>
<question id="adding-disks">
<para>How can I add my new hard disk to my &os; system?</para>
</question>
<answer>
<para>See the <ulink
url="&url.books.handbook;/disks-adding.html">Adding Disks</ulink>
section in the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="new-huge-disk">
<para>How do I move my system over to my huge new disk?</para>
</question>
<answer>
<para>The best way is to reinstall the OS on the new disk,
then move the user data over. This is highly recommended if
you have been tracking <emphasis>-STABLE</emphasis> for more
than one release, or have updated a release instead of
installing a new one. You can install booteasy on both
disks with &man.boot0cfg.8;, and dual boot them until you
are happy with the new configuration. Skip the next
paragraph to find out how to move the data after doing
this.</para>
<para>Alternatively, partition and label the new disk with either
&man.sade.8; or &man.gpart.8;. If the disks are MBR-formatted,
you can also install booteasy on both disks with
&man.boot0cfg.8;, so that you can dual boot to the old or
new system after the copying is done.</para>
<para>Now you have the new disk set up, and are ready to move
the data. Unfortunately, you cannot just blindly copy the
data. Things like device files (in
<filename class="directory">/dev</filename>), flags, and links tend to screw
that up. You need to use tools that understand these
things, which means &man.dump.8;. Although it is suggested
that you move the data in single user mode, it is not
required.</para>
<para>You should never use anything but &man.dump.8; and
&man.restore.8; to move the root file system. The
&man.tar.1; command may work — then again, it may not.
You should also use &man.dump.8; and &man.restore.8; if you
are moving a single partition to another empty partition.
The sequence of steps to use <command>dump</command> to move
a partitions data to a new partition is:</para>
<procedure>
<step>
<para><command>newfs</command> the new partition.</para>
</step>
<step>
<para><command>mount</command> it on a temporary mount
point.</para>
</step>
<step>
<para><command>cd</command> to that directory.</para>
</step>
<step>
<para><command>dump</command> the old partition, piping
output to the new one.</para>
</step>
</procedure>
<para>For example, if you are going to move root to
<devicename>/dev/<replaceable>ada1s1a</replaceable></devicename>,
with <filename class="directory"><replaceable>/mnt</replaceable></filename> as
the temporary mount point, it is:</para>
<screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput></screen>
<para>Rearranging your partitions with <command>dump</command>
takes a bit more work. To merge a partition like
<filename class="directory">/var</filename> into its parent, create the new
partition large enough for both, move the parent partition
as described above, then move the child partition into the
empty directory that the first move created:</para>
<screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput>
&prompt.root; <userinput>cd var</userinput>
&prompt.root; <userinput>dump 0af - /var | restore rf -</userinput></screen>
<para>To split a directory from its parent, say putting
<filename class="directory">/var</filename> on its own partition when it was
not before, create both partitions, then mount the child
partition on the appropriate directory in the temporary
mount point, then move the old single partition:</para>
<screen>&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1a</replaceable></userinput>
&prompt.root; <userinput>newfs /dev/<replaceable>ada1s1d</replaceable></userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1a</replaceable> <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>mkdir <replaceable>/mnt</replaceable>/var</userinput>
&prompt.root; <userinput>mount /dev/<replaceable>ada1s1d</replaceable> <replaceable>/mnt</replaceable>/var</userinput>
&prompt.root; <userinput>cd <replaceable>/mnt</replaceable></userinput>
&prompt.root; <userinput>dump 0af - / | restore rf -</userinput></screen>
<para>You might prefer &man.cpio.1;, &man.pax.1;, &man.tar.1;
to &man.dump.8; for user data. At the time of this writing,
these are known to lose file flag information, so use them
with caution.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="safe-softupdates">
<para>Which partitions can safely use Soft Updates? I have
heard that Soft Updates on <filename class="directory">/</filename> can cause
problems. What about Journaled Soft Updates?</para>
</question>
<answer>
<para>Short answer: you can usually use Soft Updates safely on
all partitions.</para>
<para>Long answer: Soft Updates has two
characteristics that may be undesirable on certain
paritions. First, a Soft Updates
partition has a small chance of losing data during a system
crash. (The partition will not be corrupted; the data will
simply be lost.) Second, Soft Updates can cause temporary
space shortages.</para>
<para>When using Soft Updates, the kernel can take up to
thirty seconds to write changes to the physical
disk. When a large file is deleted the file still
resides on
disk until the kernel actually performs the deletion. This
can cause a very simple race condition. Suppose you delete
one large file and immediately create another large file.
The first large file is not yet actually removed from the
physical disk, so the disk might not have enough room for
the second large file. You get an error that the partition
does not have enough space, although you know perfectly well
that you just released a large chunk of space! When you try
again mere seconds later, the file creation works as you
expect. This has left more than one user scratching his
head and doubting his sanity, the &os; file system, or
both.</para>
<para>If a system should crash after the kernel accepts a
chunk of data for writing to disk, but before that data is
actually written out, data could be lost. This
risk is extremely small, but generally manageable.</para>
<para>These issues affect all partitions using Soft Updates.
So, what does this mean for the root partition?</para>
<para>Vital information on the root partition changes very
rarely. If the
system crashed during the thirty-second window after such a
change is made, it is possible that data could be lost.
This risk is negligible for most applications, but you
should be aware that it exists. If your system cannot
tolerate this much risk, do not use Soft Updates on the root
file system!</para>
<para><filename class="directory">/</filename> is traditionally one of the
smallest partitions. If you put the
<filename class="directory">/tmp</filename> directory on
<filename class="directory">/</filename> and you have a busy
<filename class="directory">/tmp</filename>, you might see intermittent space
problems. Symlinking <filename class="directory">/tmp</filename> to
<filename class="directory">/var/tmp</filename> will solve this
problem.</para>
<para>Finally, &man.dump.8; does not work in live mode (-L)
on a filesystem, with Journaled Soft Updates
(<acronym>SU+J</acronym>).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="inappropriate-ccd">
<para>What is inappropriate about my &man.ccd.4;?</para>
</question>
<answer>
<para>The symptom of this is:</para>
<screen>&prompt.root; <userinput>ccdconfig -C</userinput>
ccdconfig: ioctl (CCDIOCSET): /dev/<replaceable>ccd0c</replaceable>: Inappropriate file type or format</screen>
<para>This usually happens when you are trying to concatenate
the <literal>c</literal> partitions, which default to type
<literal>unused</literal>. The &man.ccd.4; driver requires
the underlying partition type to be
<literal>FS_BSDFFS</literal>. Edit the disk label of the
disks you are trying to concatenate and change the types of
partitions to <literal>4.2BSD</literal>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ccd-disk-label">
<para>Why can I not edit the disk label on my
&man.ccd.4;?</para>
</question>
<answer>
<para>The symptom of this is:</para>
<screen>&prompt.root; <userinput>disklabel <replaceable>ccd0</replaceable></userinput>
(it prints something sensible here, so let us try to edit it)
&prompt.root; <userinput>disklabel -e <replaceable>ccd0</replaceable></userinput>
(edit, save, quit)
disklabel: ioctl DIOCWDINFO: No disk label on disk;
use "disklabel -r" to install initial label</screen>
<para>This is because the disk label returned by &man.ccd.4;
is actually a <quote>fake</quote> one that is not really on
the disk. You can solve this problem by writing it back
explicitly, as in:</para>
<screen>&prompt.root; <userinput>disklabel <replaceable>ccd0</replaceable> > <replaceable>/tmp/disklabel.tmp</replaceable></userinput>
&prompt.root; <userinput>disklabel -Rr <replaceable>ccd0</replaceable> <replaceable>/tmp/disklabel.tmp</replaceable></userinput>
&prompt.root; <userinput>disklabel -e <replaceable>ccd0</replaceable></userinput>
(this will work now)</screen>
</answer>
</qandaentry>
<qandaentry>
<question id="mount-foreign-fs">
<para>Can I mount other foreign file systems under
&os;?</para>
</question>
<answer>
<para>&os; supports a variety of other file systems.</para>
<variablelist>
<varlistentry>
<term>UFS</term>
<listitem>
<para>UFS CD-ROMs can be mounted directly on &os;.
Mounting disk partitions from Digital UNIX and other
systems that support UFS may be more complex,
depending on the details of the disk partitioning for
the operating system in question.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ext2/ext3</term>
<listitem>
<para>&os; supports <literal>ext2fs</literal> and
<literal>ext3fs</literal> partitions. See
&man.mount.ext2fs.8; for more information.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>NTFS</term>
<listitem>
<para>FUSE based NTFS support is available as a port
(<filename role="package">sysutils/fusefs-ntfs</filename>).
For more information see <ulink
url="http://www.tuxera.com/community/ntfs-3g-manual/"><application>ntfs-3g</application></ulink>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>FAT</term>
<listitem>
<para>&os; includes a read-write FAT driver. For more
information, see &man.mount.msdosfs.8;.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ZFS</term>
<listitem>
<para>&os; includes a port of
&sun;'s ZFS driver. The current recommendation is to
use it only on &arch.amd64; platforms with sufficient
memory. For more information, see &man.zfs.8;.</para>
</listitem>
</varlistentry>
</variablelist>
<para>&os; also supports network file systems such as NFS (see
&man.mount.nfs.8;), NetWare (see &man.mount.nwfs.8;), and
Microsoft-style SMB file systems (see &man.mount.smbfs.8;).
You can find ports based on FUSE (<filename
role="package">sysutils/fusefs-kmod</filename>) for many
other file systems.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="mount-dos">
<para>How do I mount a secondary DOS partition?</para>
</question>
<answer>
<para>The secondary DOS partitions are found after
<emphasis>all</emphasis> the primary partitions. For
example, if you have an <quote>E</quote> partition as the
second DOS partition on the second SCSI drive, there will be
a device file for <quote>slice 5</quote> in
<filename class="directory">/dev</filename>, so simply mount it:</para>
<screen>&prompt.root; <userinput>mount -t msdosfs /dev/da1s5 /dos/e</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="crypto-file-system">
<para>Is there a cryptographic file system for &os;?</para>
</question>
<answer>
<para>Yes. You can use either &man.gbde.8; or &man.geli.8;,
see the <ulink
url="&url.books.handbook;/disks-encrypting.html">Encrypting Disk Partitions</ulink>
section of the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="nt-bootloader">
<para>How can I use the &windowsnt; loader to boot
&os;?</para>
</question>
<answer>
<para>The general idea is that you copy the first sector of
your native root &os; partition into a file in the
DOS/&windowsnt; partition. Assuming you name that file
something like <filename>c:\bootsect.bsd</filename>
(inspired by <filename>c:\bootsect.dos</filename>), you can
then edit <filename>c:\boot.ini</filename> to come
up with something like this:</para>
<programlisting>[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Windows NT"
C:\BOOTSECT.BSD="&os;"
C:\="DOS"</programlisting>
<para>If &os; is installed on the same disk as the &windowsnt;
boot partition simply copy <filename>/boot/boot1</filename> to
<filename>C:\BOOTSECT.BSD</filename>. However, if &os; is
installed on a different disk
<filename>/boot/boot1</filename> will not work,
<filename>/boot/boot0</filename> is needed.</para>
<para><filename>/boot/boot0</filename> needs to be installed
using &man.sysinstall.8; by selecting the &os; boot manager
on the screen which asks if you wish to use a boot manager.
This is because <filename>/boot/boot0</filename> has the
partition table area filled with NULL characters but
&man.sysinstall.8; copies the partition table before copying
<filename>/boot/boot0</filename> to the MBR.</para>
<warning>
<para><emphasis>Do not simply copy
<filename>/boot/boot0</filename> instead of
<filename>/boot/boot1</filename>; you will overwrite
your partition table and render your computer
un-bootable!</emphasis></para>
</warning>
<para>When the &os; boot manager runs it records the last OS
booted by setting the active flag on the partition table
entry for that OS and then writes the whole 512-bytes of
itself back to the MBR so if you just copy
<filename>/boot/boot0</filename> to
<filename>C:\BOOTSECT.BSD</filename> then it writes an empty
partition table, with the active flag set on one entry, to
the MBR.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="lilo-bootloader">
<para>How do I boot &os; and &linux; from LILO?</para>
</question>
<answer>
<para>If you have &os; and &linux; on the same disk, just
follow LILO's installation instructions for booting a
non-&linux; operating system. Very briefly, these
are:</para>
<para>Boot &linux;, and add the following lines to
<filename>/etc/lilo.conf</filename>:</para>
<programlisting>other=/dev/hda2
table=/dev/hda
label=&os;</programlisting>
<para>(the above assumes that your &os; slice is known to
&linux; as <devicename>/dev/hda2</devicename>; tailor to
suit your setup). Then, run <command>lilo</command> as
<username>root</username> and you should be done.</para>
<para>If &os; resides on another disk, you need to add
<literal>loader=/boot/chain.b</literal> to the LILO entry.
For example:</para>
<programlisting>other=/dev/dab4
table=/dev/dab
loader=/boot/chain.b
label=&os;</programlisting>
<para>In some cases you may need to specify the BIOS drive
number to the &os; boot loader to successfully boot off the
second disk. For example, if your &os; SCSI disk is probed
by BIOS as BIOS disk 1, at the &os; boot loader prompt you
need to specify:</para>
<screen>Boot: <userinput>1:da(0,a)/boot/kernel/kernel</userinput></screen>
<para>You can configure &man.boot.8; to automatically do this
for you at boot time.</para>
<para>The <ulink
url="http://tldp.org/HOWTO/Linux+FreeBSD.html">&linux;+&os; mini-HOWTO</ulink>
is a good reference for &os; and &linux; interoperability
issues.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="grub-loader">
<para>How do I boot &os; and &linux; using GRUB?</para>
</question>
<answer>
<para>Booting &os; using GRUB is very simple. Just add the
following to your configuration file
<filename>/boot/grub/menu.lst</filename> (or
<filename>/boot/grub/grub.conf</filename> in some systems,
e.g., Red Hat Linux and its derivatives).</para>
<programlisting>title &os; 6.1
root <replaceable>(hd0,a)</replaceable>
kernel /boot/loader</programlisting>
<para>Where <replaceable>hd0,a</replaceable> points to your
root partition on the first disk. If you need to specify
which slice number should be used, use something like this
<replaceable>(hd0,2,a)</replaceable>. By default, if the
slice number is omitted, GRUB searches the first slice which
has <literal>a</literal> partition.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="booteasy-loader">
<para>How do I boot &os; and &linux; using
<application>BootEasy?</application></para>
</question>
<answer>
<para>Install LILO at the start of your &linux; boot partition
instead of in the Master Boot Record. You can then boot
LILO from <application>BootEasy</application>.</para>
<para>If you are running &windows; and &linux; this is
recommended anyway, to make it simpler to get &linux; booting
again if you should need to reinstall &windows; (which is a
Jealous Operating System, and will bear no other Operating
Systems in the Master Boot Record).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="changing-bootprompt">
<para>How do I change the boot prompt from
<literal>???</literal> to something more meaningful?</para>
</question>
<answer>
<para>You can not do that with the standard boot manager
without rewriting it. There are a number of other boot
managers in the <filename class="directory">sysutils</filename> ports category
that provide this functionality.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="removable-drives">
<para>I have a new removable drive, how do I use it?</para>
</question>
<answer>
<para>If the drive already has a
file system on it, you can use a command like this:</para>
<screen>&prompt.root; <userinput>mount -t msdosfs /dev/da0s1 /mnt</userinput></screen>
<para>If the drive will only be used with &os;
systems it is better idea to
stick a BSD file system on it, like UFS or ZFS.
You will get long filename
support, at least a 2X improvement in performance,
and a lot more stability. If the drive will be
used by other operating systems a more portable
choice, such as msdosfs, is better.</para>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=/dev/da0 count=2</userinput>
&prompt.root; <userinput>gpart create -s GPT /dev/da0</userinput>
&prompt.root; <userinput>gpart add -t freebsd-ufs /dev/da0</userinput></screen>
<para>Finally, create a new file system:</para>
<screen>&prompt.root; <userinput>newfs /dev/da0p1</userinput></screen>
<para>and mount it:</para>
<screen>&prompt.root; <userinput>mount /dev/da0s1 /mnt</userinput></screen>
<para>It is a good idea to add a line
to <filename>/etc/fstab</filename> (see &man.fstab.5;) so
you can just type <command>mount /mnt</command> in the
future:</para>
<programlisting>/dev/da0p1 /mnt ufs rw,noauto 0 0</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="mount-cd-superblock">
<para>Why do I get <errorname>Incorrect super
block</errorname> when mounting a CD-ROM?</para>
</question>
<answer>
<para>You have to tell &man.mount.8; the type of the device
that you want to mount. This is described in the <ulink
url="&url.books.handbook;/creating-cds.html"> Handbook section on optical media</ulink>,
specifically the section <ulink
url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CDs</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="cdrom-not-configured">
<para>Why do I get <errorname>Device not
configured</errorname> when mounting a CD-ROM?</para>
</question>
<answer>
<para>This generally means that there is no CD-ROM in the
CD-ROM drive, or the drive is not visible on the bus.
Please see the <ulink
url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CDs</ulink>
section of the Handbook for a detailed discussion of this
issue.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="cdrom-unicode-filenames">
<para>Why do all non-English characters in filenames show up
as <quote>?</quote> on my CDs when mounted in &os;?</para>
</question>
<answer>
<para>Your CD-ROM probably uses the <quote>Joliet</quote>
extension for storing information about files and
directories. This is discussed in the Handbook chapter on
<ulink
url="&url.books.handbook;/creating-cds.html">creating and using CD-ROMs</ulink>,
specifically the section on <ulink
url="&url.books.handbook;/creating-cds.html#mounting-cd">Using Data CD-ROMs</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="burncd-isofs">
<para>I burned a CD under &os; and now I can not read it under
any other operating system. Why?</para>
</question>
<answer>
<para>You most likely burned a raw file to your CD, rather
than creating an ISO 9660 file system. Take a look at
the <ulink
url="&url.books.handbook;/creating-cds.html">Handbook chapter on creating CD-ROMs</ulink>,
particularly the section on <ulink
url="&url.books.handbook;/creating-cds.html#rawdata-cd">burning raw data CDs</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="copy-cd">
<para>How can I create an image of a data CD?</para>
</question>
<answer>
<para>This is discussed in the Handbook section on <ulink
url="&url.books.handbook;/creating-cds.html#imaging-cd">duplicating data CDs</ulink>.
For more on working with CD-ROMs, see the <ulink
url="&url.books.handbook;/creating-cds.html">Creating CDs Section</ulink>
in the Storage chapter in the Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="mount-audio-CD">
<para>Why can I not <command>mount</command> an audio
CD?</para>
</question>
<answer>
<para>If you try to mount an audio CD, you will get an error
like <errorname>cd9660: /dev/acd0c: Invalid
argument</errorname>. This is because
<command>mount</command> only works on file systems. Audio
CDs do not have file systems; they just have data. You need
a program that reads audio CDs, such as the <filename
role="package">audio/xmcd</filename> port.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="multi-session-CD">
<para>How do I <command>mount</command> a multi-session
CD?</para>
</question>
<answer>
<para>By default, &man.mount.8; will attempt to mount the last
data track (session) of a CD. If you would like to load an
earlier session, you must use the <option>-s</option>
command line argument. Please see &man.mount.cd9660.8; for
specific examples.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="user-floppymount">
<para>How do I let ordinary users mount CD-ROMs, DVDs,
USB drives, and other removable media?</para>
</question>
<answer>
<para>As <username>root</username> set the sysctl variable
<varname>vfs.usermount</varname> to
<literal>1</literal>.</para>
<screen>&prompt.root; <userinput>sysctl vfs.usermount=1</userinput></screen>
<para>To make this persist across reboots, add the line
<literal><varname>vfs.usermount</varname>=1</literal> to
<filename>/etc/sysctl.conf</filename> so that
it is reset at system boot time.</para>
<para>Users can only mount devices they have read
permissions to. To allow users to mount a device
permissions must be set in
<filename>/etc/devfs.conf</filename>.</para>
<para>For example, to allow users to mount the first USB
drive add:</para>
<programlisting># Allow all users to mount a USB drive.
own /dev/da0 root:operator
perm /dev/da00 0666</programlisting>
<para>All users can now mount devices they could read
onto a directory that they own:</para>
<screen>&prompt.user; <userinput>mkdir <replaceable>~/my-mount-point</replaceable></userinput>
&prompt.user; <userinput>mount -t msdosfs /dev/da0<replaceable>~/my-mount-point</replaceable></userinput></screen>
<para>Unmounting the device is simple:</para>
<screen>&prompt.user; <userinput>umount <replaceable>~/my-mount-point</replaceable></userinput></screen>
<para>Enabling <varname>vfs.usermount</varname>, however, has
negative security implications. A better way to access
&ms-dos; formatted media is to use the <filename
role="package">emulators/mtools</filename> package in the
Ports Collection.</para>
<note>
<para>The device name used in the previous examples must be
changed according to your configuration.</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="du-vs-df">
<para>The <command>du</command> and <command>df</command>
commands show different amounts of disk space available.
What is going on?</para>
</question>
<answer>
<para>You need to understand what <command>du</command> and
<command>df</command> really do. <command>du</command> goes
through the directory tree, measures how large each file is,
and presents the totals. <command>df</command> just asks
the file system how much space it has left. They seem to be
the same thing, but a file without a directory entry will
affect <command>df</command> but not
<command>du</command>.</para>
<para>When a program is using a file, and you delete the file,
the file is not really removed from the file system until
the program stops using it. The file is immediately deleted
from the directory listing, however. You can see this
easily enough with a program such as
<command>more</command>. Assume you have a file large
enough that its presence affects the output of
<command>du</command> and <command>df</command>. (Since
disks can be so large today, this might be a
<emphasis>very</emphasis> large file!) If you delete this
file while using <command>more</command> on it,
<command>more</command> does not immediately choke and
complain that it cannot view the file. The entry is simply
removed from the directory so no other program or user can
access it. <command>du</command> shows that it is gone
— it has walked the directory tree and the file is not
listed. <command>df</command> shows that it is still there,
as the file system knows that <command>more</command> is
still using that space. Once you end the
<command>more</command> session, <command>du</command> and
<command>df</command> will agree.</para>
<para>Note that Soft Updates can delay the freeing of disk
space; you might need to wait up to 30 seconds for the
change to be visible!</para>
<para>This situation is common on web servers. Many people
set up a &os; web server and forget to rotate the log files.
The access log fills up <filename class="directory">/var</filename>. The new
administrator deletes the file, but the system still
complains that the partition is full. Stopping and
restarting the web server program would free the file,
allowing the system to release the disk space. To prevent
this from happening, set up &man.newsyslog.8;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="add-swap-space">
<para>How can I add more swap space?</para>
</question>
<answer>
<para>In the <ulink
url="&url.books.handbook;/config-tuning.html">Configuration and Tuning</ulink>
section of the Handbook, you will find a <ulink
url="&url.books.handbook;/adding-swap-space.html">section</ulink>
describing how to do this.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="manufacturer-disk-size">
<para>Why does &os; see my disk as smaller than the
manufacturer says it is?</para>
</question>
<answer>
<para>Disk manufacturers calculate gigabytes as a billion
bytes each, whereas &os; calculates them as
1,073,741,824 bytes each. This explains why, for
example, &os;'s boot messages will report a disk that
supposedly has 80 GB as holding 76,319 MB.</para>
<para>Also note that &os; will (by default) <link
linkend="disk-more-than-full">reserve</link> 8% of the disk
space.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="disk-more-than-full">
<para>How is it possible for a partition to be more than 100%
full?</para>
</question>
<answer>
<para>A portion of each UFS partition (8%, by default) is
reserved for use by the operating system and the
<username>root</username> user. &man.df.1; does not count
that space when calculating the <literal>Capacity</literal>
column, so it can exceed 100%. Also, you will notice that
the <literal>Blocks</literal> column is always greater than
the sum of the <literal>Used</literal> and
<literal>Avail</literal> columns, usually by a factor of
8%.</para>
<para>For more details, look up <option>-m</option>
in &man.tunefs.8;.</para>
</answer>
</qandaentry>
</qandaset>
<sect1 id="all-about-zfs">
<title>ZFS</title>
<qandaset>
<qandaentry>
<question id="how-much-ram-for-zfs">
<para>What is the minimum amount of RAM one should have to
run ZFS?</para>
</question>
<answer>
<para>A minimum of 4GB of RAM is required for comfortable
usage, but individual workloads can vary widely.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="what-is-zil">
<para>What is the ZIL and when does it get used?</para>
</question>
<answer>
<para>The <acronym>ZIL</acronym> ((<acronym>ZFS</acronym>
intent log) is a write log used to implement posix write
commitment semantics across crashes. Normally writes
are bundled up into transaction groups
and written to disk when filled (<quote>Transaction Group
Commit</quote>). However syscalls like &man.fsync.2;
require a commitment that the data is written to stable
storage before returning.
The ZIL is needed for writes that have been acknowledged
as written but which are not yet on disk as part of a
transaction. The transaction groups are timestamped.
In the event of a crash the last valid timestamp is
found and missing data is merged in from the ZIL.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="need-ssd-for-zil">
<para>Do I need a SSD for ZIL?</para>
</question>
<answer>
<para>By default, ZFS stores the ZIL in the pool with all
the data. If your application has a heavy write load,
storing the ZIL in a separate device that has very fast
synchronous, sequential write performance can improve
overall system. For other workloads, a SSD is unlikely
to make much of an improvement.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="what-is-l2arc">
<para>What is the L2ARC?</para>
</question>
<answer>
<para>The <acronym>L2ARC</acronym> is a read cache stored
on a fast device such as an <acronym>SSD</acronym>.
This cache is not persisent across
reboots. Note that RAM is used as the first layer
of cache and the L2ARC is only needed if there is
insufficient RAM.</para>
<para>L2ARC needs space in the ARC to index it. So,
perversely, a working set that fits perfectly in the
ARC will not fit perfectly any more if a L2ARC is used
because part of the ARC is holding the L2ARC index,
pushing part of the working set into the
L2ARC which is slower than RAM.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="should-enable-dedup">
<para>Is enabling deduplication advisable?</para>
</question>
<answer>
<para>Generally speaking, no.</para>
<para>Deduplication takes up a significant amount
of RAM and may slow down read and write
disk access times. Unless one is storing data that is
very heavily duplicated (such as virtual machine images,
or user backups) it is possible that deduplication will
do more harm than good. Another consideration is the
inability to revert deduplication status. If data is
written when deduplication is enabled, disabling dedup
will not cause those blocks which were deduplicated to
be replicated until they are next modified.</para>
<para>Deduplication can also lead to some unexpected
situations. In particular deleting files may become much
slower.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="zpool-fully-full">
<para>I can not delete or create files on my ZFS pool.
How can I fix this?</para>
</question>
<answer>
<para>This could happen because the pool is 100% full.
ZFS requires space on the disk to write
transaction metadata. To restore the pool
to a usable state, truncate a file you want to
delete.</para>
<screen>&prompt.user; <userinput>truncate -s 0 <replaceable>unimportant-file</replaceable></userinput></screen>
<para>File truncation works because a new transaction is
not started, new spare blocks are created instead.</para>
<note>
<para>On systems with additional ZFS dataset tuning,
such as deduplication, the space may not be immediately
available</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="zfs-ssd-trim">
<para>Does ZFS support TRIM for Solid State Drives?</para>
</question>
<answer>
<para>ZFS TRIM support was added to &os; 10-CURRENT
with revision r<svnref>240868</svnref>. ZFS TRIM
support is not yet available on the -STABLE
branches.</para>
<para>ZFS TRIM is enabled by default, and can be turned
off by adding this line to
<filename>/etc/sysctl.conf</filename>:</para>
<programlisting>vfs.zfs.trim_disable=1</programlisting>
<note>
<para>ZFS TRIM may not work with all configurations,
such as a ZFS filesystem on a GELI-backed
device.</para>
</note>
</answer>
</qandaentry>
</qandaset>
</sect1>
</chapter>
<chapter id="admin">
<title>System Administration</title>
<qandaset>
<qandaentry>
<question id="startup-config-files">
<para>Where are the system start-up configuration
files?</para>
</question>
<answer>
<para>The primary configuration file is
<filename>/etc/defaults/rc.conf</filename> (see
&man.rc.conf.5;). System startup scripts such as
<filename class="directory">/etc/rc</filename> and
<filename class="directory">/etc/rc.d</filename> (see &man.rc.8;) just include
this file. <emphasis>Do not edit this file!</emphasis>
Instead, if there is any entry in
<filename>/etc/defaults/rc.conf</filename> that you want to
change, you should copy the line into
<filename>/etc/rc.conf</filename> and change it
there.</para>
<para>For example, if you wish to start &man.named.8;, the
included DNS server, all you need to do is:</para>
<screen>&prompt.root; <userinput>echo 'named_enable="YES"' >> /etc/rc.conf</userinput></screen>
<para>To start up local services, place shell scripts in the
<filename class="directory">/usr/local/etc/rc.d</filename> directory. These
shell scripts should be set executable, the default file
mode is <literal>555</literal>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="adding-users">
<para>How do I add a user easily?</para>
</question>
<answer>
<para>Use the &man.adduser.8; command, or the &man.pw.8;
command for more complicated situations.</para>
<para>To remove the user, use the &man.rmuser.8; command or,
if necessary, &man.pw.8;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="root-not-found-cron-errors">
<para>Why do I keep getting messages like <errorname>root: not
found</errorname> after editing
<filename>/etc/crontab</filename></para>
</question>
<answer>
<para>This is normally caused by editing the system crontab
(<filename>/etc/crontab</filename>) and then using
&man.crontab.1; to install it:</para>
<screen>&prompt.root; <userinput>crontab /etc/crontab</userinput></screen>
<para>This is not the correct way to do things. The system
crontab has a different format to the per-user crontabs
which &man.crontab.1; updates (the &man.crontab.5; manual
page explains the differences in more detail).</para>
<para>If this is what you did, the extra crontab is simply a
copy of <filename>/etc/crontab</filename> in the wrong
format it. Delete it with the command:</para>
<screen>&prompt.root; <userinput>crontab -r</userinput></screen>
<para>Next time, when you edit
<filename>/etc/crontab</filename>, you should not do
anything to inform &man.cron.8; of the changes, since it
will notice them automatically.</para>
<para>If you want something to be run once per day, week, or
month, it is probably better to add shell scripts
<filename class="directory">/usr/local/etc/periodic</filename>, and let the
&man.periodic.8; command run from the system
<command>cron</command> schedule it with the other periodic
system tasks.</para>
<para>The actual reason for the error is that the system
crontab has an extra field, specifying which user to run the
command as. In the default system crontab provided with
&os;, this is <username>root</username> for all entries.
When this crontab is used as the <username>root</username>
user's crontab (which is <emphasis>not</emphasis> the same
as the system crontab), &man.cron.8; assumes the string
<literal>root</literal> is the first word of the command to
execute, but no such command exists.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="su-wheel-group">
<para>Why do I get the error, <errorname>you are not in the
correct group to su root</errorname> when I try to
<command>su</command> to <username>root</username>?</para>
</question>
<answer>
<para>This is a security feature. To
<command>su</command> to <username>root</username> (or any
other account with superuser privileges), you must be in the
<groupname>wheel</groupname> group. If this feature were
not there, anybody with an account on a system who also
found out <username>root</username>'s password would be able
to gain superuser level access to the system. With this
feature, this is not strictly true; &man.su.1; will prevent
them from even trying to enter the password if they are not
in <groupname>wheel</groupname>.</para>
<para>To allow someone to <command>su</command> to
<username>root</username>, simply put them in the
<groupname>wheel</groupname> group. Use &man.pw.8;
for this purpose.</para>
<screen>&prompt.root; <userinput>pw groupmod wheel -m <replaceable>lisa</replaceable></userinput></screen>
<para>The above example will add user
<username>lisa</username> to the group
<groupname>wheel</groupname>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="rcconf-readonly">
<para>I made a mistake in <filename>rc.conf</filename>, or
another startup file, and now I cannot edit it because the
file system is read-only. What should I do?</para>
</question>
<answer>
<para>Restart the system using <userinput>boot -s</userinput>
at the loader prompt to enter Single User mode. When
prompted for a shell pathname, simply press
<keycap>Enter</keycap>, and run
<command>mount -urw /</command> to re-mount the root file
system in read/write mode. You may also need to run
<command>mount -a -t ufs</command> to mount the file system
where your favorite editor is defined. If your favorite
editor is on a network file system, you will need to either
configure the network manually before you can mount network
file systems, or use an editor which resides on a local file
system, such as &man.ed.1;.</para>
<para>If you intend to use a full screen editor such as
&man.vi.1; or &man.emacs.1;, you may also need to run
<command>export TERM=cons25</command> so that these editors
can load the correct data from the &man.termcap.5;
database.</para>
<para>Once you have performed these steps, you can edit
<filename>/etc/rc.conf</filename> as you usually would to
fix the syntax error. The error message displayed
immediately after the kernel boot messages should tell you
the number of the line in the file which is at fault.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="printer-setup">
<para>Why am I having trouble setting up my printer?</para>
</question>
<answer>
<para>See the <ulink
url="&url.books.handbook;/printing.html">Handbook entry on printing</ulink>.
It should cover most of your problem.</para>
<para>Some printers require a host-based driver to do any kind
of printing. These so-called <quote>WinPrinters</quote> are
not natively supported by &os;. If your printer does not
work in DOS or &windows;, it is probably a WinPrinter. Your
only hope of getting one of these to work is to check if the
<filename role="package">print/pnm2ppa</filename> port
supports it.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="keyboard-mappings">
<para>How can I correct the keyboard mappings for my
system?</para>
</question>
<answer>
<para>Please see the Handbook section on <ulink
url="&url.books.handbook;/using-localization.html">using localization</ulink>,
specifically the section on <ulink
url="&url.books.handbook;/using-localization.html#setting-console">console setup</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="user-quotas">
<para>Why can I not get user quotas to work properly?</para>
</question>
<answer>
<orderedlist>
<listitem>
<para>It is possible that your kernel is not configured
to use quotas. If this is the case, you will need to
add the following line to your kernel configuration
file and recompile:</para>
<programlisting>options QUOTA</programlisting>
<para>Please read the <ulink
url="&url.books.handbook;/quotas.html">Handbook entry on quotas</ulink>
for full details.</para>
</listitem>
<listitem>
<para>Do not turn on quotas on
<filename class="directory">/</filename>.</para>
</listitem>
<listitem>
<para>Put the quota file on the file system that the
quotas are to be enforced on, i.e.:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>File System</entry>
<entry>Quota file</entry>
</row>
</thead>
<tbody>
<row>
<entry><filename class="directory">/usr</filename></entry>
<entry><filename>/usr/admin/quotas</filename></entry>
</row>
<row>
<entry><filename class="directory">/home</filename></entry>
<entry><filename>/home/admin/quotas</filename></entry>
</row>
<row>
<entry>…</entry>
<entry>…</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</listitem>
</orderedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="sysv-ipc">
<para>Does &os; support System V IPC primitives?</para>
</question>
<answer>
<para>Yes, &os; supports System V-style IPC, including shared
memory, messages and semaphores, in the
<filename>GENERIC</filename> kernel. In a custom kernel,
enable this support by adding the following lines to your
kernel config.</para>
<programlisting>options SYSVSHM # enable shared memory
options SYSVSEM # enable for semaphores
options SYSVMSG # enable for messaging</programlisting>
<para>Recompile and install your kernel.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="sendmail-alternative">
<para>What other mail-server software can I use instead of
<application>sendmail</application>?</para>
</question>
<answer>
<para>The <ulink
url="http://www.sendmail.org/"><application>sendmail</application></ulink>
server is the default mail-server software for &os;, but you
can easily replace it with one of the other MTA (for
instance, an MTA installed from the ports).</para>
<para>There are various alternative MTAs in the ports tree
already, with <filename role="package">mail/exim</filename>,
<filename role="package">mail/postfix</filename>, <filename
role="package">mail/qmail</filename>, and <filename
role="package">mail/zmailer</filename> being some of the
most popular choices.</para>
<para>Diversity is nice, and the fact that you have many
different mail-servers to chose from is considered a good
thing; therefore try to avoid asking questions like
<quote>Is <application>sendmail</application> better than
<application>qmail</application>?</quote> in the mailing
lists. If you do feel like asking, first check the mailing
list archives. The advantages and disadvantages of each and
every one of the available MTAs have already been discussed
a few times.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="forgot-root-pw">
<para>I have forgotten the <username>root</username> password!
What do I do?</para>
</question>
<answer>
<para>Do not panic! Restart the system, type
<userinput>boot -s</userinput> at the
<literal>Boot:</literal> prompt to enter Single User mode.
At the question about the shell to use, hit
<keycap>Enter</keycap>. You will be dropped to a
&prompt.root; prompt. Enter <command>mount -urw /</command>
to remount your root file system read/write, then run
<command>mount -a</command> to remount all the file systems.
Run <command>passwd root</command> to change the
<username>root</username> password then run &man.exit.1; to
continue booting.</para>
<note>
<para>If you are still prompted to give the
<username>root</username> password when entering the
Single User mode, it means that the console has been
marked as <literal>insecure</literal> in
<filename>/etc/ttys</filename>. In this case it will be
required to boot from a &os; installation disk, choose
the <guimenuitem>Live CD</guimenuitem> or
<guimenuitem>Shell</guimenuitem> at the beginning of the install
process and issue the commands mentioned above. You will need to
mount the specific partition in this case and then chroot to it,
i.e. replace <command>mount -urw /</command> by
<command>mount /dev/ada0p1 /mnt; chroot /mnt</command> for
a system on <replaceable>ada0p1</replaceable>.</para>
</note>
<note>
<para>If you cannot mount your root partition from Single
User mode, it is possible that the partitions are
encrypted and it is impossible to mount them without the
access keys. Your chances depend on the chosen
implementation. For more information see the section
about encrypted disks in the &os; <ulink
url="&url.books.handbook;/disks-encrypting.html">Handbook</ulink>.</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="CAD-reboot">
<para>How do I keep <keycombo
action="simul"><keycap>Control</keycap><keycap>Alt</keycap><keycap>Delete</keycap></keycombo>
from rebooting the system?</para>
</question>
<answer>
<para>If you are using &man.syscons.4; (the default console
driver) build and install a new kernel with the line in the
configuration file:</para>
<programlisting>options SC_DISABLE_REBOOT</programlisting>
<para>This can also be done by setting the following
&man.sysctl.8; which does not require a reboot or kernel
recompile:</para>
<screen>&prompt.root; <userinput>sysctl hw.syscons.kbd_reboot=0</userinput></screen>
<note>
<para>The above two methods are exclusive: The &man.sysctl.8;
does not exist if you compile your kernel with the
<literal>SC_DISABLE_REBOOT</literal> option.</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="dos-to-unix-txt">
<para>How do I reformat DOS text files to &unix; ones?</para>
</question>
<answer>
<para>Use this &man.perl.1; command:</para>
<screen>&prompt.user; <userinput>perl -i.bak -npe 's/\r\n/\n/g' <replaceable>file(s)</replaceable></userinput></screen>
<para>where <replaceable>file(s)</replaceable> is one or more
files to process. The modification is done in-place, with the
original file stored with a <filename>.bak</filename>
extension.</para>
<para>Alternatively you can use the &man.tr.1; command:</para>
<screen>&prompt.user; <userinput>tr -d '\r' < <replaceable>dos-text-file</replaceable> > <replaceable>unix-file</replaceable></userinput></screen>
<para><replaceable>dos-text-file</replaceable> is the file
containing DOS text while
<replaceable>unix-file</replaceable> will contain the
converted output. This can be quite a bit faster than using
<command>perl</command>.</para>
<para>Yet another way to reformat DOS text files is to use the
<filename role="package">converters/dosunix</filename> port
from the Ports Collection. Consult its documentation about
the details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="kill-by-name">
<para>How do I kill processes by name?</para>
</question>
<answer>
<para>Use &man.pkill.1;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="uninstall-kerberos">
<para>How do I uninstall
<application>Kerberos</application>?</para>
</question>
<answer>
<para>To remove <application>Kerberos</application> from the
system, reinstall the <literal>base</literal> distribution
for the release you are running. If you have the CD-ROM,
you can mount it (we will assume on <filename
class="directory">/cdrom</filename>) and run the commands
below:</para>
<screen>&prompt.root; <userinput>cd /cdrom/base</userinput>
&prompt.root; <userinput>./install.sh</userinput></screen>
<para>Alternately, you can include the
<makevar>NO_KERBEROS</makevar> option in your
<filename>/etc/make.conf</filename> and rebuild
world.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="add-pty">
<para>How do I add pseudoterminals to the system?</para>
</question>
<answer>
<para>If you have a lot of <command>telnet</command>,
<command>ssh</command>, X, or <command>screen</command>
users, you might run out of pseudoterminals. By default,
&os; supports 512 pseudoterminals.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="reread-rc">
<para>How do I re-read <filename>/etc/rc.conf</filename> and
re-start <filename>/etc/rc</filename> without a
reboot?</para>
</question>
<answer>
<para>Go into single user mode and then back to multi user
mode.</para>
<para>On the console do:</para>
<screen>&prompt.root; <userinput>shutdown now</userinput>
(Note: without -r or -h)
&prompt.root; <userinput>return</userinput>
&prompt.root; <userinput>exit</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="release-candidate">
<para>I tried to update my system to the latest
<emphasis>-STABLE</emphasis>, but got
<emphasis>-BETA<replaceable>x</replaceable></emphasis>,
<emphasis>-RC</emphasis> or
<emphasis>-PRERELEASE</emphasis>! What is going on?</para>
</question>
<answer>
<para>Short answer: it is just a name.
<emphasis>RC</emphasis> stands for <quote>Release
Candidate</quote>. It signifies that a release is imminent.
In &os;, <emphasis>-PRERELEASE</emphasis> is typically
synonymous with the code freeze before a release. (For some
releases, the <emphasis>-BETA</emphasis> label was used in
the same way as <emphasis>-PRERELEASE</emphasis>.)</para>
<para>Long answer: &os; derives its releases from one of two
places. Major, dot-zero, releases, such as 7.0-RELEASE and
8.0-RELEASE, are branched from the head of the development
stream, commonly referred to as <link
linkend="current">-CURRENT</link>. Minor releases, such as
6.3-RELEASE or 5.2-RELEASE, have been snapshots of the
active <link linkend="stable">-STABLE</link> branch.
Starting with 4.3-RELEASE, each release also now has its own
branch which can be tracked by people requiring an extremely
conservative rate of development (typically only security
advisories).</para>
<para>When a release is about to be made, the branch from
which it will be derived from has to undergo a certain
process. Part of this process is a code freeze. When a
code freeze is initiated, the name of the branch is changed
to reflect that it is about to become a release. For
example, if the branch used to be called 6.2-STABLE, its
name will be changed to 6.3-PRERELEASE to signify the code
freeze and signify that extra pre-release testing should be
happening. Bug fixes can still be committed to be part of
the release. When the source code is in shape for the
release the name will be changed to 6.3-RC to signify that a
release is about to be made from it. Once in the RC stage,
only the most critical bugs found can be fixed. Once the
release (6.3-RELEASE in this example) and release branch
have been made, the branch will be renamed to
6.3-STABLE.</para>
<para>For more information on version numbers and the various
Subversion branches, refer to the <ulink
url="&url.articles.releng;/article.html">Release Engineering</ulink>
article.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="kernel-chflag-failure">
<para>I tried to install a new kernel, and the &man.chflags.1;
failed. How do I get around this?</para>
</question>
<answer>
<para>Short answer: You are probably at security level greater
than 0. Reboot directly to Single User mode to install the
kernel.</para>
<para>Long answer: &os; disallows changing system flags at
security levels greater than 0. You can check your security
level with the command:</para>
<screen>&prompt.root; <userinput>sysctl kern.securelevel</userinput></screen>
<para>You cannot lower the security level; you have to boot to
Single Mode to install the kernel, or change the security
level in <filename>/etc/rc.conf</filename> then reboot. See
the &man.init.8; manual page for details on
<literal>securelevel</literal>, and see
<filename>/etc/defaults/rc.conf</filename> and the
&man.rc.conf.5; manual page for more information on
<filename>rc.conf</filename>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="kernel-securelevel-time">
<para>I cannot change the time on my system by more than one
second! How do I get around this?</para>
</question>
<answer>
<para>Short answer: You are probably at security level greater
than 1. Reboot directly to Single User mode to change the
date.</para>
<para>Long answer: &os; disallows changing the time by more
that one second at security levels greater than 1. You can
check your security level with the command:</para>
<screen>&prompt.root; <userinput>sysctl kern.securelevel</userinput></screen>
<para>You cannot lower the security level; you have to boot to
Single User mode to change the date, or change the security
level in <filename>/etc/rc.conf</filename> then reboot. See
the &man.init.8; manual page for details on
<literal>securelevel</literal>, and see
<filename>/etc/defaults/rc.conf</filename> and the
&man.rc.conf.5; manual page for more information on
<filename>rc.conf</filename>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="statd-mem-leak">
<para>Why is <command>rpc.statd</command> using 256 MB of
memory?</para>
</question>
<answer>
<para>No, there is no memory leak, and it is not using
256 MB of memory. For convenience,
<command>rpc.statd</command> maps an obscene amount of
memory into its address space. There is nothing terribly
wrong with this from a technical standpoint; it just throws
off things like &man.top.1; and &man.ps.1;.</para>
<para>&man.rpc.statd.8; maps its status file (resident on
<filename class="directory">/var</filename>) into its address space; to save
worrying about remapping it later when it needs to grow, it
maps it with a generous size. This is very evident from the
source code, where one can see that the length argument to
&man.mmap.2; is <literal>0x10000000</literal>, or one
sixteenth of the address space on an IA32, or exactly
256 MB.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="unsetting-schg">
<para>Why can I not unset the <literal>schg</literal> file
flag?</para>
</question>
<answer>
<para>You are running at an elevated (i.e., greater than 0)
securelevel. Lower the securelevel and try again. For more
information, see <link linkend="securelevel">the FAQ entry
on securelevel</link> and the &man.init.8; manual
page.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ssh-shosts">
<para>Why does <application>SSH</application> authentication
through <filename>.shosts</filename> not work by default in
recent versions of &os;?</para>
</question>
<answer>
<para>The reason why <filename>.shosts</filename>
authentication does not work by default in more recent
versions of &os; is because &man.ssh.1; is not installed
suid <username>root</username> by default. To
<quote>fix</quote> this, you can do one of the
following:</para>
<itemizedlist>
<listitem>
<para>As a permanent fix, set
<makevar>ENABLE_SUID_SSH</makevar> to
<literal>true</literal> in
<filename>/etc/make.conf</filename> then rebuild and
reinstall &man.ssh.1;.</para>
</listitem>
<listitem>
<para>As a temporary fix, change the mode on
<filename>/usr/bin/ssh</filename> to
<literal>4555</literal> by running
<command>chmod 4555 /usr/bin/ssh</command> as
<username>root</username>.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="vnlru">
<para>What is <literal>vnlru</literal>?</para>
</question>
<answer>
<para><literal>vnlru</literal> flushes and frees vnodes when
the system hits the <varname>kern.maxvnodes</varname> limit.
This kernel thread sits mostly idle, and only activates if
you have a huge amount of RAM and are accessing tens of
thousands of tiny files.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="top-memory-states">
<para>What do the various memory states displayed by
<command>top</command> mean?</para>
</question>
<!-- Provided by John Dyson via Usenet -->
<answer>
<itemizedlist>
<listitem>
<para><literal>Active</literal>: pages recently
statistically used.</para>
</listitem>
<listitem>
<para><literal>Inactive</literal>: pages recently
statistically unused.</para>
</listitem>
<listitem>
<para><literal>Cache</literal>: (most often) pages that
have percolated from inactive to a status where they
maintain their data, but can often be immediately reused
(either with their old association, or reused with a new
association). There can be certain immediate transitions
from <literal>active</literal> to
<literal>cache</literal> state if the page is known to
be clean (unmodified), but that transition is a matter
of policy, depending upon the algorithm choice of the VM
system maintainer.</para>
</listitem>
<listitem>
<para><literal>Free</literal>: pages without data content,
and can be immediately used in certain circumstances
where cache pages might be ineligible. Free pages can
be reused at interrupt or process
state.</para>
</listitem>
<listitem>
<para><literal>Wired</literal>: pages that are fixed into
memory, usually for kernel purposes, but also sometimes
for special use in processes.</para>
</listitem>
</itemizedlist>
<para>Pages are most often written to disk (sort of a VM sync)
when they are in the inactive state, but active pages can
also be synced. This depends upon the CPU tracking of the
modified bit being available, and in certain situations
there can be an advantage for a block of VM pages to be
synced, whether they are active or inactive. In most common
cases, it is best to think of the inactive queue to be a
queue of relatively unused pages that might or might not be
in the process of being written to disk. Cached pages are
already synced, not mapped, but available for immediate
process use with their old association or with a new
association. Free pages are available at interrupt level,
but cached or free pages can be used at process state for
reuse. Cache pages are not adequately locked to be
available at interrupt level.</para>
<para>There are some other flags (e.g., busy flag or busy
count) that might modify some of the described rules.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="free-memory-amount">
<para>How much free memory is available?</para>
</question>
<!-- Provided by John Dyson via Usenet -->
<answer>
<para>There are a couple of kinds of <quote>free
memory</quote>. One kind is the amount of memory
immediately available without paging anything else out.
That is approximately the size of cache queue + size of free
queue (with a derating factor, depending upon system
tuning). Another kind of <quote>free memory</quote> is the
total amount of <acronym>VM</acronym> space. That can be
complex, but is dependent upon the amount of swap space and
memory. Other kinds of <quote>free memory</quote>
descriptions are also possible, but it is relatively useless
to define these, but rather it is important to make sure
that the paging rate is kept low, and to avoid running out
of swap space.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="var-empty">
<para>What is <filename class="directory">/var/empty</filename>? I can not
delete it!</para>
</question>
<answer>
<para><filename class="directory">/var/empty</filename> is a directory that the
&man.sshd.8; program uses when performing privilege separation.
The <filename class="directory">/var/empty</filename> directory is empty, owned by
<username>root</username> and has the <literal>schg</literal>
flag set.</para>
<para>Although it is not recommended to delete this directory, to
do so you will need to unset the <literal>schg</literal> flag
first. See the &man.chflags.1; manual page for more information
(and bear in mind the answer to
<link linkend="unsetting-schg">the question on unsetting the schg flag</link>).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="newsyslog-expectations">
<para>I just changed
<filename>/etc/newsyslog.conf</filename>. How can I check
if it does what I expect?</para>
</question>
<answer>
<para>To see what &man.newsyslog.8; will do use the
following:</para>
<screen>&prompt.user; <userinput>newsyslog -nrvv</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="timezone">
<para>My time is wrong, how can I change the
timezone?</para>
</question>
<answer>
<para>Use &man.tzsetup.8;.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="x">
<title>The X Window System and Virtual Consoles</title>
<qandaset>
<qandaentry>
<question id="whatis-X">
<para>What is the X Window System?</para>
</question>
<answer>
<para>The X Window System (commonly <literal>X11</literal>) is
the most widely available windowing system capable of running
on &unix; or &unix; like systems, including &os;.
<ulink url= "http://www.x.org/wiki/">The X.Org Foundation</ulink>
administers the <ulink
url="http://en.wikipedia.org/wiki/X_Window_System_core_protocol">X protocol standards</ulink>,
with the current reference implementation, version 11
release &xorg.version;, so you will often see references
shortened to <literal>X11</literal>.</para>
<para>Many implementations are available for different
architectures and operating systems. An implementation of
the server-side code is properly known as an <literal>X
server</literal>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="running-X">
<para>I want to run &xorg;, how do I go about it?</para>
</question>
<answer>
<para>To install &xorg; do one of the following:</para>
<para>Use the <filename role="package">x11/xorg</filename>
meta-port, which builds and installs every &xorg;
component.</para>
<para>Use <filename
role="package">x11/xorg-minimal</filename>, which builds
and installs only the necessary &xorg; components.</para>
<para>Install &xorg; from &os; packages:</para>
<screen><userinput>&prompt.root; pkg_add -r xorg</userinput></screen>
<para>or on systems using <application>pkg</application>:</para>
<screen><userinput>&prompt.root; pkg install xorg</userinput></screen>
<para>After the installation of &xorg;, follow
the instructions from the <ulink
url="&url.books.handbook;/x-config.html">X11 Configuration</ulink> section of
the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="running-X-securelevels">
<para>I <emphasis>tried</emphasis> to run X, but I get a
<errorname>No devices detected.</errorname> error when I
type
<command>startx</command>. What do I do now?</para>
</question>
<answer>
<para>Your system is probably running at a raised
<literal>securelevel</literal>. It is not possible to start X
at a raised <literal>securelevel</literal> because X
requires write access to &man.io.4;. For more information,
see at the &man.init.8; manual page.</para>
<para>There are two solutions to the problem:
Set your
<literal>securelevel</literal> back down to zero (usually
in <filename>/etc/rc.conf</filename>), or run &man.xdm.1;
(or an alternative display manager)
at boot time (before the <literal>securelevel</literal> is
raised).</para>
<para>See <xref linkend="xdm-boot"/> for more information about
running &man.xdm.1; at boot time.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="x-and-moused">
<para>Why does my mouse not work with X?</para>
</question>
<answer>
<para>If you are using &man.syscons.4; (the default console
driver), you can configure &os; to support a mouse pointer on
each virtual screen. To avoid conflicting with X,
&man.syscons.4; supports a virtual device called
<devicename>/dev/sysmouse</devicename>. All mouse events
received from the real mouse device are written to the
&man.sysmouse.4; device via &man.moused.8;. To use your
mouse on one or more virtual consoles,
<emphasis>and</emphasis> use X, see <xref
linkend="moused" remap="another section"/> and set up
&man.moused.8;.</para>
<para>Then edit <filename>/etc/X11/xorg.conf</filename> and
make sure you have the following lines:</para>
<programlisting>Section "InputDevice"
Option "Protocol" "SysMouse"
Option "Device" "/dev/sysmouse"
.....</programlisting>
<para>Starting with &xorg; version 7.4, the
<literal>InputDevice</literal> sections in
<filename>xorg.conf</filename> are ignored in favor of
autodetected devices. To restore the old behavior, add the
following line to the <literal>ServerLayout</literal> or
<literal>ServerFlags</literal> section:</para>
<programlisting>Option "AutoAddDevices" "false"</programlisting>
<para>Some people prefer to use
<devicename>/dev/mouse</devicename> under X. To make this
work, <devicename>/dev/mouse</devicename> should be linked
to <devicename>/dev/sysmouse</devicename> (see
&man.sysmouse.4;) by adding the following line to
<filename>/etc/devfs.conf</filename> (see
&man.devfs.conf.5;):</para>
<programlisting>link sysmouse mouse</programlisting>
<para>This link can be created by restarting &man.devfs.5;
with the following command (as
<username>root</username>):</para>
<screen>&prompt.root; <userinput>service devfs restart</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="x-and-wheel">
<para>My mouse has a fancy wheel. Can I use it in X?</para>
</question>
<answer>
<para>Yes.</para>
<para>You need to tell X that you have a 5 button mouse. To
do this, simply add the lines <literal>Buttons 5</literal>
and <literal>ZAxisMapping 4 5</literal> to the
<quote>InputDevice</quote> section of
<filename>/etc/X11/xorg.conf</filename>. For example, you
might have the following <quote>InputDevice</quote> section
in <filename>/etc/X11/xorg.conf</filename>.</para>
<example>
<title><quote>InputDevice</quote> Section for Wheeled Mouse
in &xorg; Configuration File</title>
<programlisting>Section "InputDevice"
Identifier "Mouse1"
Driver "mouse"
Option "Protocol" "auto"
Option "Device" "/dev/sysmouse"
Option "Buttons" "5"
Option "ZAxisMapping" "4 5"
EndSection</programlisting>
</example>
<example>
<title><quote>.emacs</quote> Example for Naive Page
Scrolling with Wheeled Mouse (optional)</title>
<programlisting>;; wheel mouse
(global-set-key [mouse-4] 'scroll-down)
(global-set-key [mouse-5] 'scroll-up)</programlisting>
</example>
</answer>
</qandaentry>
<qandaentry>
<question id="x-and-synaptic">
<para>My laptop has a Synaptics touchpad. Can I use
it in X?</para>
</question>
<answer>
<para>Yes, you will have to configure a few things to
make it work.</para>
<para>If you plan to use the Xorg synaptics driver you
<emphasis>must</emphasis> remove moused_enable from
<filename>rc.conf</filename>. Xorg can not use
the synaptics mouse if the moused already sits on
<filename>/dev/psm0</filename>.</para>
<para>To enable synaptics in the &man.psm.4; driver you need
to add the following into
<filename>/boot/loader.conf</filename>:</para>
<programlisting>hw.psm.synaptics_support="1"</programlisting>
<para>You also need the following into
<filename>xorg.conf</filename>:</para>
<programlisting>Section "InputDevice"
Identifier "Touchpad0"
Driver "synaptics"
Option "Protocol" "psm"
Option "Device" "/dev/psm0"
EndSection</programlisting>
<para>And be sure to add the following into the
<quote>ServerLayout</quote> section:</para>
<programlisting>InputDevice "Touchpad0" "SendCoreEvents"</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="no-remote-x11">
<para>How do I use remote X displays?</para>
</question>
<answer>
<para>For security reasons, the default setting is to not
allow a machine to remotely open a window.</para>
<para>To enable this feature, simply start
<application>X</application> with the optional
<option>-listen_tcp</option> argument:</para>
<screen>&prompt.user; <userinput>startx -listen_tcp</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="virtual-console">
<para>What is a virtual console and how do I make more?</para>
</question>
<answer>
<para>Virtual consoles, put simply, enable you to have several
simultaneous sessions on the same machine without doing
anything complicated like setting up a network or running
X.</para>
<para>When the system starts, it will display a login prompt
on the monitor after displaying all the boot messages. You
can then type in your login name and password and start
working (or playing!) on the first virtual console.</para>
<para>At some point, you will probably wish to start another
session, perhaps to look at documentation for a program you
are running or to read your mail while waiting for an FTP
transfer to finish. Just do <keycombo
action="simul"><keycap>Alt</keycap><keycap>F2</keycap></keycombo>
(hold down <keycap>Alt</keycap> and press
<keycap>F2</keycap>), and you will find a login prompt
waiting for you on the second <quote>virtual
console</quote>! When you want to go back to the original
session, do <keycombo
action="simul"><keycap>Alt</keycap><keycap>F1</keycap></keycombo>.</para>
<para>The default &os; installation has eight virtual consoles
enabled. <keycombo
action="simul"><keycap>Alt</keycap><keycap>F1</keycap></keycombo>,
<keycombo
action="simul"><keycap>Alt</keycap><keycap>F2</keycap></keycombo>,
<keycombo
action="simul"><keycap>Alt</keycap><keycap>F3</keycap></keycombo>,
and so on will switch between these virtual consoles.</para>
<para>To enable more of them, edit
<filename>/etc/ttys</filename> (see &man.ttys.5;) and add
entries for <devicename>ttyv8</devicename> to
<devicename>ttyvc</devicename> after the comment on
<quote>Virtual terminals</quote>:</para>
<programlisting># Edit the existing entry for ttyv8 in /etc/ttys and change
# "off" to "on".
ttyv8 "/usr/libexec/getty Pc" cons25 on secure
ttyv9 "/usr/libexec/getty Pc" cons25 on secure
ttyva "/usr/libexec/getty Pc" cons25 on secure
ttyvb "/usr/libexec/getty Pc" cons25 on secure</programlisting>
<para>Use as many or as few as you want. The more virtual
terminals you have, the more resources that are used; this
can be important if you have 8 MB RAM or less. You may
also want to change the <literal>secure</literal> to
<literal>insecure</literal>.</para>
<important>
<para>If you want to run an X server you
<emphasis>must</emphasis> leave at least one virtual
terminal unused (or turned off) for it to use. That is to
say that if you want to have a login prompt pop up for all
twelve of your Alt-function keys, you are out of luck
— you can only do this for eleven of them if you
also want to run an X server on the same machine.</para>
</important>
<para>The easiest way to disable a console is by turning it
off. For example, if you had the full 12 terminal
allocation mentioned above and you wanted to run X, you
would change settings for virtual terminal 12 from:</para>
<programlisting>ttyvb "/usr/libexec/getty Pc" cons25 on secure</programlisting>
<para>to:</para>
<programlisting>ttyvb "/usr/libexec/getty Pc" cons25 off secure</programlisting>
<para>If your keyboard has only ten function keys, you would
end up with:</para>
<programlisting>ttyv9 "/usr/libexec/getty Pc" cons25 off secure
ttyva "/usr/libexec/getty Pc" cons25 off secure
ttyvb "/usr/libexec/getty Pc" cons25 off secure</programlisting>
<para>(You could also just delete these lines.)</para>
<para>Next, the easiest (and cleanest) way to activate the
virtual consoles is to reboot. However, if you really do
not want to reboot, you can just shut down the X Window
system and execute (as <username>root</username>):</para>
<screen>&prompt.root; <userinput>kill -HUP 1</userinput></screen>
<para>It is imperative that you completely shut down X Window
if it is running, before running this command. If you do not,
your system will probably appear to hang or lock up after
executing <command>kill</command>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="vty-from-x">
<para>How do I access the virtual consoles from X?</para>
</question>
<answer>
<para>Use <keycombo
action="simul"><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>F<replaceable>n</replaceable></keycap></keycombo>
to switch back to a virtual console. <keycombo
action="simul"><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>F1</keycap></keycombo>
would return you to the first virtual console.</para>
<para>Once you are back to a text console, you can then use
<keycombo
action="simul"><keycap>Alt</keycap><keycap>F<replaceable>n</replaceable></keycap></keycombo>
as normal to move between them.</para>
<para>To return to the X session, you must switch to the
virtual console running X. If you invoked X from the
command line, (e.g., using <command>startx</command>) then
the X session will attach to the next unused virtual
console, not the text console from which it was invoked. If
you have eight active virtual terminals then X will be
running on the ninth, and you would use <keycombo
action="simul"><keycap>Alt</keycap><keycap>F9</keycap></keycombo>
to return.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="xdm-boot">
<para>How do I start <application>XDM</application> on
boot?</para>
</question>
<answer>
<para>There are two schools of thought on how to start
&man.xdm.1;. One school starts <command>xdm</command> from
<filename>/etc/ttys</filename> (see &man.ttys.5;) using the
supplied example, while the other simply runs
<command>xdm</command> from
<filename>rc.local</filename> (see &man.rc.8;) or from an
<filename>X</filename> script in
<filename class="directory">/usr/local/etc/rc.d</filename>. Both are equally
valid, and one may work in situations where the other does
not. In both cases the result is the same: X will pop up a
graphical login prompt.</para>
<para>The &man.ttys.5; method has the advantage of documenting
which vty X will start on and passing the responsibility of
restarting the X server on logout to &man.init.8;. The
&man.rc.8; method makes it easy to <command>kill</command>
<command>xdm</command> if there is a problem starting the X
server.</para>
<para>If loaded from &man.rc.8;, <command>xdm</command> should
be started without any arguments (i.e., as a daemon).
<command>xdm</command> must start
<emphasis>after</emphasis> &man.getty.8; runs, or else
<command>getty</command> and <command>xdm</command> will
conflict, locking out the console. The best way around this
is to have the script sleep 10 seconds or so then launch
<command>xdm</command>.</para>
<para>If you are to start <command>xdm</command> from
<filename>/etc/ttys</filename>, there still is a chance of
conflict between <command>xdm</command> and &man.getty.8;.
One way to avoid this is to add the <literal>vt</literal>
number in
<filename>/usr/local/lib/X11/xdm/Xservers</filename></para>
<programlisting>:0 local /usr/local/bin/X vt4</programlisting>
<para>The above example will direct the X server to run in
<devicename>/dev/ttyv3</devicename>. Note the number is
offset by one. The X server counts the vty from one,
whereas the &os; kernel numbers the vty from zero.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="xconsole-failure">
<para>Why do I get <errorname>Couldn't open
console</errorname> when I run
<command>xconsole</command>?</para>
</question>
<answer>
<para>If you start <application>X</application> with
<command>startx</command>, the permissions on
<devicename>/dev/console</devicename> will
<emphasis>not</emphasis> get changed, resulting in things
like <command>xterm -C</command> and
<command>xconsole</command> not working.</para>
<para>This is because of the way console permissions are set
by default. On a multi-user system, one does not
necessarily want just any user to be able to write on the
system console. For users who are logging directly onto a
machine with a VTY, the &man.fbtab.5; file exists to solve
such problems.</para>
<para>In a nutshell, make sure an uncommented line of the form
is in <filename>/etc/fbtab</filename> (see
&man.fbtab.5;):</para>
<programlisting>/dev/ttyv0 0600 /dev/console</programlisting>
<para>It will ensure that whomever logs in on
<devicename>/dev/ttyv0</devicename> will own the
console.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ps2-x">
<para>Why does my PS/2 mouse misbehave under X?</para>
</question>
<answer>
<para>Your mouse and the mouse driver may have somewhat become
out of synchronization.</para>
<para> In rare cases the driver may erroneously report
synchronization problem and you may see the kernel
message:</para>
<programlisting>psmintr: out of sync (xxxx != yyyy)</programlisting>
<para>and notice that your mouse does not work
properly.</para>
<para>If this happens, disable the synchronization check code
by setting the driver flags for the PS/2 mouse driver to
<literal>0x100</literal>. Enter
<emphasis>UserConfig</emphasis> by giving the
<option>-c</option> option at the boot prompt:</para>
<screen>boot: <userinput>-c</userinput></screen>
<para>Then, in the <emphasis>UserConfig</emphasis> command
line, type:</para>
<screen>UserConfig> <userinput>flags psm0 0x100</userinput>
UserConfig> <userinput>quit</userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="mouse-button-reverse">
<para>How do I reverse the mouse buttons?</para>
</question>
<answer>
<para>Run the command <command>xmodmap -e "pointer = 3 2 1"</command>
from <filename>.xinitrc</filename> or
<filename>.xsession</filename>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="install-splash">
<para>How do I install a splash screen and where do I find
them?</para>
</question>
<answer>
<para>The detailed answer for this question can be found in
the <ulink
url="&url.books.handbook;/boot-blocks.html#boot-splash">Boot Time Splash Screens</ulink>
section of the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="windows-keys">
<para>Can I use the <keycap>Windows</keycap> keys on my
keyboard in X?</para>
</question>
<answer>
<para>Yes. All you need to do is use &man.xmodmap.1; to
define what function you wish them to perform.</para>
<para>Assuming all <quote>Windows</quote> keyboards are
standard then the keycodes for these three keys are the
following:</para>
<itemizedlist>
<listitem>
<para><keycode>115</keycode> —
<keycap>Windows</keycap> key, between the left-hand
<keycap>Ctrl</keycap> and <keycap>Alt</keycap>
keys</para>
</listitem>
<listitem>
<para><keycode>116</keycode> —
<keycap>Windows</keycap> key, to the right of
<keycap>AltGr</keycap></para>
</listitem>
<listitem>
<para><keycode>117</keycode> — <keycap>Menu</keycap>
key, to the left of the right-hand <keycap>Ctrl</keycap>
key</para>
</listitem>
</itemizedlist>
<para>To have the left <keycap>Windows</keycap> key print a
comma, try this.</para>
<screen>&prompt.root; <userinput>xmodmap -e "keycode 115 = comma"</userinput></screen>
<para>To have the <keycap>Windows</keycap> key-mappings
enabled automatically every time you start X either put the
<command>xmodmap</command> commands in your
<filename>~/.xinitrc</filename> file or, preferably, create
a file <filename>~/.xmodmaprc</filename> and include the
<command>xmodmap</command> options, one per line, then add
the following line to your
<filename>~/.xinitrc</filename>:</para>
<programlisting>xmodmap $HOME/.xmodmaprc</programlisting>
<para>For example, you could map the 3 keys to be
<keycap>F13</keycap>, <keycap>F14</keycap>, and
<keycap>F15</keycap>, respectively. This would make it easy
to map them to useful functions within applications or your
window manager, as demonstrated further down.</para>
<para>To do this put the following in
<filename>~/.xmodmaprc</filename>.</para>
<programlisting>keycode 115 = F13
keycode 116 = F14
keycode 117 = F15</programlisting>
<para>If you use the <filename
role="package">x11-wm/fvwm2</filename> port, for example,
you could map the keys so that <keycap>F13</keycap>
iconifies (or de-iconifies) the window the cursor is in,
<keycap>F14</keycap> brings the window the cursor is in to
the front or, if it is already at the front, pushes it to
the back, and <keycap>F15</keycap> pops up the main
Workplace (application) menu even if the cursor is not on
the desktop, which is useful if you do not have any part of
the desktop visible (and the logo on the key matches its
functionality).</para>
<para>The following entries in <filename>~/.fvwmrc</filename>
implement the aforementioned setup:</para>
<programlisting>Key F13 FTIWS A Iconify
Key F14 FTIWS A RaiseLower
Key F15 A A Menu Workplace Nop</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="x-3d-acceleration">
<para>How can I get 3D hardware acceleration for
&opengl;?</para>
</question>
<answer>
<para>The availability of 3D acceleration depends on the
version of &xorg; that you are using and the type of video
chip you have. If you have an nVidia chip, you can use the
binary drivers provided for &os; by installing one of the
following ports:</para>
<itemizedlist>
<listitem>
<para>The latest versions of nVidia cards are supported by
the <filename role="package">x11/nvidia-driver</filename>
port.</para>
</listitem>
<listitem>
<para>nVidia cards like the GeForce2 MX/3/4 series
are supported by the 96XX series of drivers, available
in the <filename
role="package">x11/nvidia-driver-96xx</filename>
port.</para>
</listitem>
<listitem>
<para>Even older cards, like GeForce and RIVA TNT are
supported by the 71XX series of drivers, available in
the <filename
role="package">x11/nvidia-driver-71xx</filename>
port.</para>
</listitem>
</itemizedlist>
<para>nVidia provides detailed information on which
card is supported by which driver
on their web site: <ulink
url="http://www.nvidia.com/object/IO_32667.html"></ulink>.</para>
<para>For Matrox G200/G400, check the
<filename role="package">x11-servers/mga_hal</filename>
port.</para>
<para>For ATI Rage 128 and Radeon see
&man.ati.4x;, &man.r128.4x; and &man.radeon.4x;.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="networking">
<title>Networking</title>
<qandaset>
<qandaentry>
<question id="diskless-booting">
<para>Where can I get information on <quote>diskless
booting</quote>?</para>
</question>
<answer>
<para><quote>Diskless booting</quote> means that the &os;
box is booted over a network, and reads the necessary
files from a server instead of its hard disk. For full
details, please read <ulink
url="&url.books.handbook;/network-diskless.html">the Handbook entry on diskless booting</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="router">
<para>Can a &os; box be used as a dedicated network
router?</para>
</question>
<answer>
<para>Yes. Please see the Handbook entry on <ulink
url="&url.books.handbook;/advanced-networking.html">advanced networking</ulink>,
specifically the section on <ulink
url="&url.books.handbook;/network-routing.html">routing and gateways</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="win95-connection">
<para>Can I connect my &windows; box to the Internet via
&os;?</para>
</question>
<answer>
<para>Typically, people who ask this question have two PCs at
home, one with &os; and one with some version of &windows;
the idea is to use the &os; box to connect to the Internet
and then be able to access the Internet from the &windows;
box through the &os; box. This is really just a special
case of the previous question and works perfectly
well.</para>
<para>Dialup users must use <option>-nat</option>
and set
<literal>gateway_enable</literal> to
<emphasis>YES</emphasis> in
<filename>/etc/rc.conf</filename>.
For
more information, please see the &man.ppp.8; manual page or
the <ulink
url="&url.books.handbook;/userppp.html">Handbook entry on user PPP</ulink>.</para>
<para>If you are using kernel-mode PPP or have an Ethernet
connection to the Internet, you need to use &man.natd.8;.
Please look at the <ulink
url="&url.books.handbook;/network-natd.html">natd</ulink>
section of the Handbook for a tutorial.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="slip-ppp-support">
<para>Does &os; support PPP?</para>
</question>
<answer>
<para>Yes. &man.ppp.8; provides support for both
incoming and outgoing connections.</para>
<para>For more information on how to use this, please see the
<ulink
url="&url.books.handbook;/ppp-and-slip.html">Handbook chapter on PPP</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="natd">
<para>Does &os; support NAT or Masquerading?</para>
</question>
<answer>
<para>Yes. If you want to use NAT over a user PPP connection,
please see the <ulink
url="&url.books.handbook;/userppp.html">Handbook entry on user PPP</ulink>.
If you want to use NAT over some other sort of network
connection, please look at the <ulink
url="&url.books.handbook;/network-natd.html">natd</ulink>
section of the Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ethernet-aliases">
<para>How can I set up Ethernet aliases?</para>
</question>
<answer>
<para>If the alias is on the same subnet as an address already
configured on the interface, then add <literal>netmask
0xffffffff</literal> to your &man.ifconfig.8; command-line,
as in the following:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ed0</replaceable> alias <replaceable>192.0.2.2</replaceable> netmask 0xffffffff</userinput></screen>
<para>Otherwise, just specify the network address and netmask
as usual:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ed0</replaceable> alias <replaceable>172.16.141.5</replaceable> netmask 0xffffff00</userinput></screen>
<para>You can read more about this in the &os; <ulink
url="&url.books.handbook;/configtuning-virtual-hosts.html">Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="port-3c503">
<para>How do I get my 3C503 to use the other network
port?</para>
</question>
<answer>
<para>If you want to use the other ports, you will have to
specify an additional parameter on the &man.ifconfig.8;
command line. The default port is <literal>link0</literal>.
To use the AUI port instead of the BNC one, use
<literal>link2</literal>. These flags should be specified
using the ifconfig_* variables in
<filename>/etc/rc.conf</filename> (see
&man.rc.conf.5;).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="nfs-linux">
<para>Why can I not NFS-mount from a &linux; box?</para>
</question>
<answer>
<para>Some versions of the &linux; NFS code only accept mount
requests from a privileged port; try to issue the following
command:</para>
<screen>&prompt.root; <userinput>mount -o -P <replaceable>linuxbox:/blah</replaceable> <replaceable>/mnt</replaceable></userinput></screen>
</answer>
</qandaentry>
<qandaentry>
<question id="exports-errors">
<para>Why does <command>mountd</command> keep telling me it
<errorname>can't change attributes</errorname> and that I
have a <errorname>bad exports list</errorname> on my &os;
NFS server?</para>
</question>
<answer>
<para>The most frequent problem is not understanding the
correct format of <filename>/etc/exports</filename>. Please
review &man.exports.5; and the <ulink
url="&url.books.handbook;/network-nfs.html">NFS</ulink>
entry in the Handbook, especially the section on <ulink
url="&url.books.handbook;/network-nfs.html#configuring-nfs">configuring NFS</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ip-multicast">
<para>How do I enable IP multicast support?</para>
</question>
<answer>
<para>&os; supports multicast host operations by default. If
you want your box to run as a multicast router, you need to
recompile your kernel with the <literal>MROUTING</literal>
option and run &man.mrouted.8;. &os; will start
&man.mrouted.8; at boot time if the flag
<literal>mrouted_enable</literal> is set to
<literal>YES</literal> in
<filename>/etc/rc.conf</filename>.</para>
<note>
<para>In recent &os; releases, the &man.mrouted.8; multicast
routing daemon, the &man.map-mbone.8; and &man.mrinfo.8;
utilities have been removed from the base system. These
programs are now available in the &os; Ports Collection as
<filename role="package">net/mrouted</filename>.</para>
</note>
<para>MBONE tools are available in their own ports category,
<ulink
url="http://www.FreeBSD.org/ports/mbone.html">mbone</ulink>.
If you are looking for the conference tools
<command>vic</command> and <command>vat</command>, look
there!</para>
</answer>
</qandaentry>
<qandaentry>
<question id="fqdn-hosts">
<para>Why do I have to use the FQDN for hosts on my
site?</para>
</question>
<answer>
<para>See the answer in the &os; <ulink
url="&url.books.handbook;/mail-trouble.html">Handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="network-permission-denied">
<para>Why do I get an error, <errorname>Permission
denied</errorname>, for all networking operations?</para>
</question>
<answer>
<para>If you have compiled your kernel with the
<literal>IPFIREWALL</literal> option, you need to be aware
that the default policy is to deny all packets that are not
explicitly allowed.</para>
<para>If you had unintentionally misconfigured your system for
firewalling, you can restore network operability by typing
the following while logged in as
<username>root</username>:</para>
<screen>&prompt.root; <userinput>ipfw add 65534 allow all from any to any</userinput></screen>
<para>You can also set <literal>firewall_type="open"</literal>
in <filename>/etc/rc.conf</filename>.</para>
<para>For further information on configuring a &os; firewall,
see the <ulink
url="&url.books.handbook;/firewalls.html">Handbook chapter</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ipfw-fwd">
<para>Why is my <command>ipfw</command> <quote>fwd</quote>
rule to redirect a service to another machine not
working?</para>
</question>
<answer>
<para>Possibly because you want to do network address
translation (NAT) and not just forward packets. A
<quote>fwd</quote> rule does exactly what it says; it
forwards packets. It does not actually change the data
inside the packet. Say we have a rule like:</para>
<screen>01000 fwd <replaceable>10.0.0.1</replaceable> from any to <replaceable>foo 21</replaceable></screen>
<para>When a packet with a destination address of
<replaceable>foo</replaceable> arrives at the machine with
this rule, the packet is forwarded to
<replaceable>10.0.0.1</replaceable>, but it still has the
destination address of <replaceable>foo</replaceable>! The
destination address of the packet is
<emphasis>not</emphasis> changed to
<replaceable>10.0.0.1</replaceable>. Most machines would
probably drop a packet that they receive with a destination
address that is not their own. Therefore, using a
<quote>fwd</quote> rule does not often work the way the user
expects. This behavior is a feature and not a bug.</para>
<para>See the <link
linkend="service-redirect">FAQ about redirecting services</link>,
the &man.natd.8; manual, or one of the several port
redirecting utilities in the <ulink
url="&url.base;/ports/index.html">Ports Collection</ulink>
for a correct way to do this.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="service-redirect">
<para>How can I redirect service requests from one machine to
another?</para>
</question>
<answer>
<para>You can redirect FTP (and other service) request with
the <filename role="package">sysutils/socket</filename>
port. Simply replace the service's command line to call
<command>socket</command> instead, like so:</para>
<programlisting>ftp stream tcp nowait nobody /usr/local/bin/socket socket <replaceable>ftp.example.com</replaceable> <replaceable>ftp</replaceable></programlisting>
<para>where <replaceable>ftp.example.com</replaceable> and
<replaceable>ftp</replaceable> are the host and port to
redirect to, respectively.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="bandwidth-mgr-tool">
<para>Where can I get a bandwidth management tool?</para>
</question>
<answer>
<para>There are three bandwidth management tools available for
&os;. &man.dummynet.4; is integrated into &os; as part of
&man.ipfw.4;. <ulink
url="http://www.sonycsl.co.jp/person/kjc/programs.html">ALTQ</ulink>
has been integrated into &os; as part of &man.pf.4;.
Bandwidth Manager from <ulink
url="http://www.etinc.com/">Emerging Technologies</ulink>
is a commercial product.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="bpf-not-configured">
<para>Why do I get <errorname>/dev/bpf0: device not
configured</errorname>?</para>
</question>
<answer>
<para>You are running a program that requires the Berkeley
Packet Filter (&man.bpf.4;), but it is not in your kernel.
Add this to your kernel config file and build a new
kernel:</para>
<programlisting>device bpf # Berkeley Packet Filter</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="mount-smb-share">
<para>How do I mount a disk from a &windows; machine that is
on my network, like smbmount in &linux;?</para>
</question>
<answer>
<para>Use the <application>SMBFS</application> toolset. It
includes a set of kernel modifications and a set of userland
programs. The programs and information are available as
&man.mount.smbfs.8; in the base system.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="icmp-response-bw-limit">
<para>What are these messages about: <errorname>Limiting
icmp/open port/closed port response</errorname> in my log
files?</para>
</question>
<answer>
<para>This is the kernel telling you that some activity is
provoking it to send more ICMP or TCP reset (RST) responses
than it thinks it should. ICMP responses are often
generated as a result of attempted connections to unused UDP
ports. TCP resets are generated as a result of attempted
connections to unopened TCP ports. Among others, these are
the kinds of activities which may cause these
messages:</para>
<itemizedlist>
<listitem>
<para>Brute-force denial of service (DoS) attacks (as
opposed to single-packet attacks which exploit a
specific vulnerability).</para>
</listitem>
<listitem>
<para>Port scans which attempt to connect to a large
number of ports (as opposed to only trying a few
well-known ports).</para>
</listitem>
</itemizedlist>
<para>The first number in the message tells you how many
packets the kernel would have sent if the limit was not in
place, and the second number tells you the limit. You can
control the limit using the
<varname>net.inet.icmp.icmplim</varname> sysctl variable
like this, where <literal>300</literal> is the limit in
packets per second:</para>
<screen>&prompt.root; <userinput>sysctl net.inet.icmp.icmplim=300</userinput></screen>
<para>If you do not want to see messages about this in your
log files, but you still want the kernel to do response
limiting, you can use the
<varname>net.inet.icmp.icmplim_output</varname> sysctl
variable to disable the output like this:</para>
<screen>&prompt.root; <userinput>sysctl net.inet.icmp.icmplim_output=0</userinput></screen>
<para>Finally, if you want to disable response limiting, you
can set the <varname>net.inet.icmp.icmplim</varname> sysctl
variable (see above for an example) to <literal>0</literal>.
Disabling response limiting is discouraged for the reasons
listed above.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="unknown-hw-addr-format">
<para>What are these <errorname>arp: unknown hardware address
format</errorname> error messages?</para>
</question>
<answer>
<para>This means that some device on your local Ethernet is
using a MAC address in a format that &os; does not
recognize. This is probably caused by someone experimenting
with an Ethernet card somewhere else on the network. You
will see this most commonly on cable modem networks. It is
harmless, and should not affect the performance of your &os;
machine.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="arp-wrong-iface">
<para>Why do I keep seeing messages like: <errorname>192.168.0.10 is on
fxp1 but got reply from 00:15:17:67:cf:82 on rl0</errorname>, and how do I
disable it?</para>
</question>
<answer>
<para>Because a packet is coming from outside the network
unexpectedly. To disable them, set
<varname>net.link.ether.inet.log_arp_wrong_iface</varname>
to <literal>0</literal>.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="security">
<title>Security</title>
<qandaset>
<qandaentry>
<question id="sandbox">
<para>What is a sandbox?</para>
</question>
<answer>
<para><quote>Sandbox</quote> is a security term. It can mean
two things:</para>
<itemizedlist>
<listitem>
<para>A process which is placed inside a set of virtual
walls that are designed to prevent someone who breaks
into the process from being able to break into the wider
system.</para>
<para>The process is said to be able to
<quote>play</quote> inside the walls. That is, nothing
the process does in regards to executing code is
supposed to be able to breech the walls so you do not
have to do a detailed audit of its code to be able to
say certain things about its security.</para>
<para>The walls might be a user ID, for example.
This is the definition used in the &man.security.7; and
&man.named.8; man pages.</para>
<para>Take the <literal>ntalk</literal> service, for
example (see &man.inetd.8;). This service used to run
as user ID <username>root</username>. Now it runs
as user ID <username>tty</username>. The
<username>tty</username> user is a sandbox designed to
make it more difficult for someone who has successfully
hacked into the system via <literal>ntalk</literal> from
being able to hack beyond that user ID.</para>
</listitem>
<listitem>
<para>A process which is placed inside a simulation of the
machine. This is more hard-core. Basically it means
that someone who is able to break into the process may
believe that he can break into the wider machine but is,
in fact, only breaking into a simulation of that machine
and not modifying any real data.</para>
<para>The most common way to accomplish this is to build a
simulated environment in a subdirectory and then run the
processes in that directory chroot'd (i.e., <filename
class="directory">/</filename> for that process is this
directory, not the real <filename
class="directory">/</filename> of the system).</para>
<para>Another common use is to mount an underlying file
system read-only and then create a file system layer on
top of it that gives a process a seemingly writeable
view into that file system. The process may believe it
is able to write to those files, but only the process
sees the effects — other processes in the system
do not, necessarily.</para>
<para>An attempt is made to make this sort of sandbox so
transparent that the user (or hacker) does not realize
that he is sitting in it.</para>
</listitem>
</itemizedlist>
<para>&unix; implements two core sandboxes. One is at the
process level, and one is at the userid level.</para>
<para>Every &unix; process is completely firewalled off from
every other &unix; process. One process cannot modify the
address space of another. This is unlike &windows; where a
process can easily overwrite the address space of any other,
leading to a crash.</para>
<para>A &unix; process is owned by a particular userid. If
the user ID is not the <username>root</username> user,
it serves to firewall the process off from processes owned
by other users. The user ID is also used to firewall
off on-disk data.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="securelevel">
<para>What is securelevel?</para>
</question>
<answer>
<para><literal>securelevel</literal> is a security
mechanism implemented in the kernel. When the securelevel
is positive, the
kernel restricts certain tasks; not even the superuser
(i.e., <username>root</username>) is allowed to do them.
The securelevel mechanism limits the ability to:</para>
<itemizedlist>
<listitem>
<para>Unset certain file flags, such as
<literal>schg</literal> (the system immutable
flag).</para>
</listitem>
<listitem>
<para>Write to kernel memory via
<devicename>/dev/mem</devicename> and
<devicename>/dev/kmem</devicename>.</para>
</listitem>
<listitem>
<para>Load kernel modules.</para>
</listitem>
<listitem>
<para>Alter firewall rules.</para>
</listitem>
</itemizedlist>
<para>To check the status of the securelevel on a running
system, simply execute the following command:</para>
<screen>&prompt.root; <userinput>sysctl -n kern.securelevel</userinput></screen>
<para>The output contains the current value of the
securelevel. If it is positive (i.e., greater than 0), at
least some of the securelevel's protections are
enabled.</para>
<para>The securelevel of a running system can not be
lowered as this would defeat its purpose. If you need
to do a task that requires that the securelevel be
non-positive (e.g., an <maketarget>installworld</maketarget>
or changing the date), you will have to change the
securelevel setting in <filename>/etc/rc.conf</filename>
(you want to look for the
<varname>kern_securelevel</varname> and
<varname>kern_securelevel_enable</varname> variables) and
reboot.</para>
<para>For more information on securelevel and the specific
things all the levels do, please consult the &man.init.8;
manual page.</para>
<warning>
<para>Securelevel is not a silver bullet; it has many known
deficiencies. More often than not, it provides a false
sense of security.</para>
<para>One of its biggest problems is that in order for it to
be at all effective, all files used in the boot process up
until the securelevel is set must be protected. If an
attacker can get the system to execute their code prior to
the securelevel being set (which happens quite late in the
boot process since some things the system must do at
start-up cannot be done at an elevated securelevel), its
protections are invalidated. While this task of
protecting all files used in the boot process is not
technically impossible, if it is achieved, system
maintenance will become a nightmare since one would have
to take the system down, at least to single-user mode, to
modify a configuration file.</para>
<para>This point and others are often discussed on the
mailing lists, particularly the &a.security;. Please
search the archives <ulink
url="&url.base;/search/index.html">here</ulink> for an
extensive discussion. A more fine-grained mechanism
is preffered.</para>
</warning>
</answer>
</qandaentry>
<qandaentry>
<question id="extra-named-port">
<para>BIND (<command>named</command>) is listening on
some high-numbered ports. What is going on?</para>
</question>
<answer>
<para>BIND uses a random high-numbered port for outgoing
queries. Recent versions of it choose a new, random UDP
port for each query. This may cause problems for some
network configurations, especially if a firewall blocks
incoming UDP packets on particular ports. If you want to
get past that firewall, you can try the
<literal>avoid-v4-udp-ports</literal> and
<literal>avoid-v6-udp-ports</literal> options to avoid
selecting random port numbers within a blocked range.</para>
<warning>
<para>If a port number (like 53) is specified via the
<literal>query-source</literal> or
<literal>query-source-v6</literal> options in
<filename>/etc/namedb/named.conf</filename>, randomized
port selection will not be used. It is strongly
recommended that these options not be used to specify
fixed port numbers.</para>
</warning>
<para>Congratulations, by the way. It is good practice to
read your &man.sockstat.1; output and notice odd
things!</para>
</answer>
</qandaentry>
<qandaentry>
<question id="sendmail-port-587">
<para>The <application>sendmail</application> daemon is
listening on port 587 as well as the standard port 25! What
is going on?</para>
</question>
<answer>
<para>Recent versions of <application>sendmail</application>
support a mail submission feature that runs over port 587.
This is not yet widely supported, but is growing in
popularity.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="toor-account">
<para>What is this UID 0 <username>toor</username> account?
Have I been compromised?</para>
</question>
<answer>
<para>Do not worry. <username>toor</username> is an
<quote>alternative</quote> superuser account (toor is root
spelt backwards). Previously it was created when the
&man.bash.1; shell was installed but now it is created by
default. It is intended to be used with a non-standard
shell so you do not have to change
<username>root</username>'s default shell. This is
important as shells which are not part of the base
distribution (for example a shell installed from ports or
packages) are likely to be installed in
<filename class="directory">/usr/local/bin</filename> which, by default,
resides on a different file system. If
<username>root</username>'s shell is located in
<filename class="directory">/usr/local/bin</filename> and
<filename class="directory">/usr</filename> (or whatever file system contains
<filename class="directory">/usr/local/bin</filename>) is not mounted for some
reason, <username>root</username> will not be able to log in
to fix a problem (although if you reboot into single user
mode you will be prompted for the path to a shell).</para>
<para>Some people use <username>toor</username> for day-to-day
<username>root</username> tasks with a non-standard shell,
leaving <username>root</username>, with a standard shell,
for single user mode or emergencies. By default you cannot
log in using <username>toor</username> as it does not have a
password, so log in as <username>root</username> and set a
password for <username>toor</username> if you want to use
it.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="ppp">
<title>PPP</title>
<qandaset>
<qandaentry>
<question id="userppp">
<para>I cannot make &man.ppp.8; work. What am I doing
wrong?</para>
</question>
<answer>
<para>You should first read the &man.ppp.8; manual page and
the <ulink
url="&url.books.handbook;/ppp-and-slip.html#userppp">PPP section of the handbook</ulink>.
Enable logging with the following command:</para>
<programlisting>set log Phase Chat Connect Carrier lcp ipcp ccp command</programlisting>
<para>This command may be typed at the &man.ppp.8; command
prompt or it may be entered in the
<filename>/etc/ppp/ppp.conf</filename> configuration file
(the start of the <literal>default</literal> section is the
best place to put it). Make sure that
<filename>/etc/syslog.conf</filename> (see
&man.syslog.conf.5;) contains the lines below and the file
<filename>/var/log/ppp.log</filename> exists:</para>
<programlisting>!ppp
*.* /var/log/ppp.log</programlisting>
<para>You can now find out a lot about what is going on from
the log file. Do not worry if it does not all make sense.
If you need to get help from someone, it may make sense to
them.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-hangs">
<para>Why does &man.ppp.8; hang when I run it?</para>
</question>
<answer>
<para>This is usually because your hostname will not resolve.
The best way to fix this is to make sure that
<filename>/etc/hosts</filename> is consulted by your
resolver first by editing
<filename>/etc/host.conf</filename> and putting the
<literal>hosts</literal> line first. Then, simply put an
entry in <filename>/etc/hosts</filename> for your local
machine. If you have no local network, change your
<hostid>localhost</hostid> line:</para>
<programlisting>127.0.0.1 foo.example.com foo localhost</programlisting>
<para>Otherwise, simply add another entry for your host.
Consult the relevant manual pages for more details.</para>
<para>You should be able to successfully
<command>ping -c1 `hostname`</command> when you are
done.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-nodial-auto">
<para>Why will &man.ppp.8; not dial in
<literal>-auto</literal> mode?</para>
</question>
<answer>
<para>First, check that you have got a default route. By
running <command>netstat -rn</command> (see
&man.netstat.1;), you should see two entries like
this:</para>
<programlisting>Destination Gateway Flags Refs Use Netif Expire
default 10.0.0.2 UGSc 0 0 tun0
10.0.0.2 10.0.0.1 UH 0 0 tun0</programlisting>
<para>This is assuming that you have used the addresses from
the handbook, the manual page, or from
<filename>ppp.conf.sample</filename>. If you do not
have a default route, it may be because you forgot to add
the <literal>HISADDR</literal> line to
<filename>ppp.conf</filename>.</para>
<para>Another reason for the default route line being missing
is that you have mistakenly set up a default router in your
<filename>/etc/rc.conf</filename> (see &man.rc.conf.5;) file
and you have omitted the line below from
<filename>ppp.conf</filename>:</para>
<programlisting>delete ALL</programlisting>
<para>If this is the case, go back to the <ulink
url="&url.books.handbook;/userppp.html#userppp-final">Final System Configuration</ulink>
section of the handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="no-route-to-host">
<para>What does <errorname>No route to host</errorname>
mean?</para>
</question>
<answer>
<para>This error is usually due that the following section is
missing in your <filename>/etc/ppp/ppp.linkup</filename>:</para>
<programlisting>MYADDR:
delete ALL
add 0 0 HISADDR</programlisting>
<para>This is only necessary if you have a dynamic IP address
or do not know the address of your gateway. If you are
using interactive mode, you can type the following after
entering <literal>packet mode</literal> (packet mode is
indicated by the capitalized <acronym>PPP</acronym> in the
prompt):</para>
<programlisting>delete ALL
add 0 0 HISADDR</programlisting>
<para>Refer to the <ulink
url="&url.books.handbook;/userppp.html#userppp-dynamicip">PPP and Dynamic IP addresses</ulink>
section of the handbook for further details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="connection-threeminutedrop">
<para>Why does my connection drop after about 3
minutes?</para>
</question>
<answer>
<para>The default PPP timeout is 3 minutes. This can be
adjusted with the following line:</para>
<programlisting>set timeout <replaceable>NNN</replaceable></programlisting>
<para>where <replaceable>NNN</replaceable> is the number of
seconds of inactivity before the connection is closed. If
<replaceable>NNN</replaceable> is zero, the connection is
never closed due to a timeout. It is possible to put this
command in <filename>ppp.conf</filename>, or to
type it at the prompt in interactive mode. It is also
possible to adjust it on the fly while the line is active by
connecting to <application>ppp</application>'s server socket
using &man.telnet.1; or &man.pppctl.8;. Refer to the
&man.ppp.8; man page for further details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-drop-heavy-load">
<para>Why does my connection drop under heavy load?</para>
</question>
<answer>
<para>If you have Link Quality Reporting (LQR) configured, it
is possible that too many LQR packets are lost between your
machine and the peer. &man.ppp.8; deduces that
the line must therefore be bad, and disconnects.
LQR is disabled by default and can be enabled with the
following line:</para>
<programlisting>enable lqr</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-drop-random">
<para>Why does my connection drop after a random amount of
time?</para>
</question>
<answer>
<para>Sometimes, on a noisy phone line or even on a line with
call waiting enabled, your modem may hang up because it
thinks (incorrectly) that it lost carrier.</para>
<para>There is a setting on most modems for determining how
tolerant it should be to temporary losses of carrier.
Refer to the modem manual for details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-hangs-random">
<para>Why does my connection hang after a random amount of
time?</para>
</question>
<answer>
<para>Many people experience hung connections with no apparent
explanation. The first thing to establish is which side of
the link is hung.</para>
<para>If you are using an external modem, you can simply try
using &man.ping.8; to see if the <acronym>TD</acronym> light
is flashing when you transmit data. If it flashes (and the
<acronym>RD</acronym> light does not), the problem is with
the remote end. If <acronym>TD</acronym> does not flash,
the problem is local. With an internal modem, you will need
to use the <literal>set server</literal> command in your
<filename>ppp.conf</filename> file. When the hang occurs,
connect to &man.ppp.8; using &man.pppctl.8;. If your
network connection suddenly revives (PPP was revived due to
the activity on the diagnostic socket) or if you cannot
connect (assuming the <literal>set socket</literal> command
succeeded at startup time), the problem is local. If you
can connect and things are still hung, enable local async
logging with <literal>set log local async</literal> and use
&man.ping.8; from another window or terminal to make use of
the link. The async logging will show you the data being
transmitted and received on the link. If data is going out
and not coming back, the problem is remote.</para>
<para>Having established whether the problem is local or
remote, you now have two possibilities:</para>
<itemizedlist>
<listitem>
<para>If the problem is remote, read on entry <xref
linkend="ppp-remote-not-responding"/>.</para>
</listitem>
<listitem>
<para>If the problem is local, read on entry <xref
linkend="ppp-hung"/>.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-remote-not-responding">
<para>The remote end is not responding. What can I do?</para>
</question>
<answer>
<para>There is very little you can do about this. Most ISPs
will refuse to help if you are not running a µsoft; OS.
You can <literal>enable lqr</literal> in your
<filename>ppp.conf</filename>, allowing &man.ppp.8; to
detect the remote failure and hang up, but this detection is
relatively slow and therefore not that useful. You may want
to avoid telling your ISP that you are running
user-PPP.</para>
<para>First, try disabling all local compression by adding the
following to your configuration:</para>
<programlisting>disable pred1 deflate deflate24 protocomp acfcomp shortseq vj
deny pred1 deflate deflate24 protocomp acfcomp shortseq vj</programlisting>
<para>Then reconnect to ensure that this makes no difference.
If things improve or if the problem is solved completely,
determine which setting makes the difference through trial
and error. This will provide good ammunition when you
contact your ISP (although it may make it apparent that you
are not running a µsoft; product).</para>
<para>Before contacting your ISP, enable async logging locally
and wait until the connection hangs again. This may use up
quite a bit of disk space. The last data read from the port
may be of interest. It is usually ASCII data, and may even
describe the problem (<errorname>Memory fault</errorname>,
<errorname>Core dumped</errorname>).</para>
<para>If your ISP is helpful, they should be able to enable
logging on their end, then when the next link drop occurs,
they may be able to tell you why their side is having a
problem.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-hung">
<para>&man.ppp.8; has hung. What can I do?</para>
</question>
<answer>
<para>Your best bet here is to rebuild &man.ppp.8; with
debugging information, and then use &man.gdb.1; to grab a
stack trace from the <application>ppp</application> process
that is stuck. To rebuild the
<application>ppp</application> utility with debugging
information, you can type:</para>
<screen>&prompt.root; <userinput>cd /usr/src/usr.sbin/ppp</userinput>
&prompt.root; <userinput>env DEBUG_FLAGS='-g' make clean</userinput>
&prompt.root; <userinput>env DEBUG_FLAGS='-g' make install</userinput></screen>
<para>Then you should restart <application>ppp</application>
and wait until it hangs again. When the debug build of
<application>ppp</application> hangs, start
<application>gdb</application> on the stuck process by
typing:</para>
<screen>&prompt.root; <userinput>gdb ppp `pgrep ppp`</userinput></screen>
<para>At the <application>gdb</application> prompt, you can
use the <command>bt</command> or <command>where</command>
commands to get a stack trace. Save the output of your
<application>gdb</application> session, and
<quote>detach</quote> from the running process by the
<command>quit</command> command of
<application>gdb</application>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-same-magic">
<para>I keep seeing errors about magic being the same. What
does it mean?</para>
</question>
<answer>
<para>Occasionally, just after connecting, you may see
messages in the log that say <errorname>Magic is
same</errorname>. Sometimes, these messages are harmless,
and sometimes one side or the other exits. Most PPP
implementations cannot survive this problem, and even if the
link seems to come up, you will see repeated configure
requests and configure acknowledgments in the log file until
&man.ppp.8; eventually gives up and closes the
connection.</para>
<para>This normally happens on server machines with slow disks
that are spawning a &man.getty.8; on the port, and executing
&man.ppp.8; from a login script or program after login.
There were reports of it happening consistently when using
slirp. The reason is that in the time taken between
&man.getty.8; exiting and &man.ppp.8; starting, the
client-side &man.ppp.8; starts sending Line Control Protocol
(LCP) packets. Because ECHO is still switched on for the
port on the server, the client &man.ppp.8; sees these
packets <quote>reflect</quote> back.</para>
<para>One part of the LCP negotiation is to establish a magic
number for each side of the link so that
<quote>reflections</quote> can be detected. The protocol
says that when the peer tries to negotiate the same magic
number, a NAK should be sent and a new magic number should
be chosen. During the period that the server port has ECHO
turned on, the client &man.ppp.8; sends LCP packets, sees
the same magic in the reflected packet and NAKs it. It also
sees the NAK reflect (which also means &man.ppp.8; must
change its magic). This produces a potentially enormous
number of magic number changes, all of which are happily
piling into the server's tty buffer. As soon as &man.ppp.8;
starts on the server, it is flooded with magic number
changes and almost immediately decides it has tried enough
to negotiate LCP and gives up. Meanwhile, the client, who
no longer sees the reflections, becomes happy just in time
to see a hangup from the server.</para>
<para>This can be avoided by allowing the peer to start
negotiating with the following line in
<filename>ppp.conf</filename>:</para>
<programlisting>set openmode passive</programlisting>
<para>This tells &man.ppp.8; to wait for the server to
initiate LCP negotiations. Some servers however may never
initiate negotiations. If this is the case, you can do
something like:</para>
<programlisting>set openmode active 3</programlisting>
<para>This tells &man.ppp.8; to be passive for 3 seconds, and
then to start sending LCP requests. If the peer starts
sending requests during this period, &man.ppp.8; will
immediately respond rather than waiting for the full 3
second period.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-lcp-constant">
<para>LCP negotiations continue until the connection is
closed. What is wrong?</para>
</question>
<answer>
<para>There is currently an implementation mis-feature in
&man.ppp.8; where it does not associate LCP, CCP & IPCP
responses with their original requests. As a result, if one
PPP implementation is more than 6 seconds slower than the
other side, the other side will send two additional LCP
configuration requests. This is fatal.</para>
<para>Consider two implementations, <hostid>A</hostid> and
<hostid>B</hostid>. <hostid>A</hostid> starts sending LCP
requests immediately after connecting and <hostid>B</hostid>
takes 7 seconds to start. When <hostid>B</hostid> starts,
<hostid>A</hostid> has sent 3 LCP REQs. We are assuming the
line has ECHO switched off, otherwise we would see magic
number problems as described in the previous section.
<hostid>B</hostid> sends a REQ, then an ACK to the first of
<hostid>A</hostid>'s REQs. This results in
<hostid>A</hostid> entering the <acronym>OPENED</acronym>
state and sending and ACK (the first) back to
<hostid>B</hostid>. In the meantime, <hostid>B</hostid>
sends back two more ACKs in response to the two additional
REQs sent by <hostid>A</hostid> before <hostid>B</hostid>
started up. <hostid>B</hostid> then receives the first ACK
from <hostid>A</hostid> and enters the
<acronym>OPENED</acronym> state. <hostid>A</hostid>
receives the second ACK from <hostid>B</hostid> and goes
back to the <acronym>REQ-SENT</acronym> state, sending
another (forth) REQ as per the RFC. It then receives the
third ACK and enters the <acronym>OPENED</acronym> state.
In the meantime, <hostid>B</hostid> receives the forth REQ
from <hostid>A</hostid>, resulting in it reverting to the
<acronym>ACK-SENT</acronym> state and sending another
(second) REQ and (forth) ACK as per the RFC.
<hostid>A</hostid> gets the REQ, goes into
<acronym>REQ-SENT</acronym> and sends another REQ. It
immediately receives the following ACK and enters
<acronym>OPENED</acronym>.</para>
<para>This goes on until one side figures out that they are
getting nowhere and gives up.</para>
<para>The best way to avoid this is to configure one side to
be <literal>passive</literal> — that is, make one side
wait for the other to start negotiating. This can be done
with the following command:</para>
<programlisting>set openmode passive</programlisting>
<para>Care should be taken with this option. You should also
use this command to limit the amount of time that
&man.ppp.8; waits for the peer to begin negotiations:</para>
<programlisting>set stopped <replaceable>N</replaceable></programlisting>
<para>Alternatively, the following command (where
<replaceable>N</replaceable> is the number of seconds to
wait before starting negotiations) can be used:</para>
<programlisting>set openmode active <replaceable>N</replaceable></programlisting>
<para>Check the manual page for details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-shell-test-lockup">
<para>Why does &man.ppp.8; lock up when I shell out to test
it?</para>
</question>
<answer>
<para>When you execute the <command>shell</command> or
<command>!</command> command, &man.ppp.8; executes a shell
(or if you have passed any arguments, &man.ppp.8; will
execute those arguments). The
<application>ppp</application> program will wait for the
command to complete before continuing. If you attempt to
use the PPP link while running the command, the link will
appear to have frozen. This is because &man.ppp.8; is
waiting for the command to complete.</para>
<para>To execute commands like this, use
<command>!bg</command> instead. This will execute
the given command in the background, and &man.ppp.8; can
continue to service the link.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-null-modem">
<para>Why does &man.ppp.8; over a null-modem cable never
exit?</para>
</question>
<answer>
<para>There is no way for &man.ppp.8; to automatically
determine that a direct connection has been dropped. This
is due to the lines that are used in a null-modem serial
cable. When using this sort of connection, LQR should
always be enabled with the following line:</para>
<programlisting>enable lqr</programlisting>
<para>LQR is accepted by default if negotiated by the
peer.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-auto-noreasondial">
<para>Why does &man.ppp.8; dial for no reason in
<option>-auto</option> mode?</para>
</question>
<answer>
<para>If &man.ppp.8; is dialing unexpectedly, you must
determine the cause, and set up Dial filters (dfilters) to
prevent such dialing.</para>
<para>To determine the cause, use the following line:</para>
<programlisting>set log +tcp/ip</programlisting>
<para>This will log all traffic through the connection. The
next time the line comes up unexpectedly, you will see the
reason logged with a convenient timestamp next to it.</para>
<para>You can now disable dialing under these circumstances.
Usually, this sort of problem arises due to DNS lookups. To
prevent DNS lookups from establishing a connection (this
will <emphasis>not</emphasis> prevent &man.ppp.8; from
passing the packets through an established connection), use
the following:</para>
<programlisting>set dfilter 1 deny udp src eq 53
set dfilter 2 deny udp dst eq 53
set dfilter 3 permit 0/0 0/0</programlisting>
<para>This is not always suitable, as it will effectively
break your demand-dial capabilities — most programs
will need a DNS lookup before doing any other network
related things.</para>
<para>In the DNS case, you should try to determine what is
actually trying to resolve a host name. A lot of the time,
&man.sendmail.8; is the culprit. You should make sure that
you tell <application>sendmail</application> not to do any
DNS lookups in its configuration file. See the section on
<ulink
url="&url.books.handbook;/smtp-dialup.html">using email with a dialup connection</ulink>
in the &os; Handbook for details on how to create your own
configuration file and what should go into it. You may also
want to add the following line to your
<filename>.mc</filename> file:</para>
<programlisting>define(`confDELIVERY_MODE', `d')dnl</programlisting>
<para>This will make <application>sendmail</application> queue
everything until the queue is run (usually, sendmail is
run with <option>-bd -q30m</option>, telling it to run
the queue every 30 minutes) or until a <command>sendmail
<option>-q</option></command> is done (perhaps from your
<filename>ppp.linkup</filename>).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ccp-errors">
<para>What do these CCP errors mean?</para>
</question>
<answer>
<para>I keep seeing the following errors in my log
file:</para>
<programlisting>CCP: CcpSendConfigReq
CCP: Received Terminate Ack (1) state = Req-Sent (6)</programlisting>
<para>This is because &man.ppp.8; is trying to negotiate
Predictor1 compression, and the peer does not want to
negotiate any compression at all. The messages are
harmless, but if you wish to remove them, you can disable
Predictor1 compression locally too:</para>
<programlisting>disable pred1</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-connectionspeed">
<para>Why does &man.ppp.8; not log my connection speed?</para>
</question>
<answer>
<para>To log all lines of your modem
<quote>conversation</quote>, you must enable the
following:</para>
<programlisting>set log +connect</programlisting>
<para>This will make &man.ppp.8; log everything up until the
last requested <quote>expect</quote> string.</para>
<para>If you wish to see your connect speed and are using PAP
or CHAP (and therefore do not have anything to
<quote>chat</quote> after the CONNECT in the dial script
— no <literal>set login</literal> script), you must
make sure that you instruct &man.ppp.8; to
<quote>expect</quote> the whole CONNECT line, something like
this:</para>
<programlisting>set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 4 \
\"\" ATZ OK-ATZ-OK ATDT\\T TIMEOUT 60 CONNECT \\c \\n"</programlisting>
<para>Here, we get our CONNECT, send nothing, then expect a
line-feed, forcing &man.ppp.8; to read the whole CONNECT
response.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-ignores-backslash">
<para>Why does &man.ppp.8; ignore the <literal>\</literal>
character in my chat script?</para>
</question>
<answer>
<para>The <application>ppp</application> utility parses each
line in your config files so that it can interpret strings
such as <literal>set phone "123 456 789"</literal> correctly
and realize that the number is actually only
<emphasis>one</emphasis> argument. To specify a
<literal>"</literal> character, you must escape it
using a backslash (<literal>\</literal>).</para>
<para>When the chat interpreter parses each argument, it
re-interprets the argument to find any special
escape sequences such as <literal>\P</literal> or
<literal>\T</literal> (see the manual page). As a result of
this double-parsing, you must remember to use the correct
number of escapes.</para>
<para>If you wish to actually send a <literal>\</literal>
character to (say) your modem, you would need something
like:</para>
<programlisting>set dial "\"\" ATZ OK-ATZ-OK AT\\\\X OK"</programlisting>
<para>It will result in the following sequence:</para>
<programlisting>ATZ
OK
AT\X
OK</programlisting>
<para>Or:</para>
<programlisting>set phone 1234567
set dial "\"\" ATZ OK ATDT\\T"</programlisting>
<para>It will result in the following sequence:</para>
<programlisting>ATZ
OK
ATDT1234567</programlisting>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-segfault-nocore">
<para>Why does &man.ppp.8; get a <errorname>Segmentation
fault</errorname>, but I see no <filename>ppp.core</filename>
file?</para>
</question>
<answer>
<para>The <application>ppp</application> utility (or any other
program for that matter) should never dump core. Because
&man.ppp.8; runs setuid (with an effective user ID of
<literal>0</literal>), the operating system will not write
core image of &man.ppp.8; to disk before terminating it.
If, however &man.ppp.8; is actually terminating due to a
segmentation violation or some other signal that normally
causes core to be dumped, <emphasis>and</emphasis> you are
sure you are using the latest version (see the start of this
section), then you should install the system sources and do
the following:</para>
<screen>&prompt.root; <userinput><command>cd</command> <filename class="directory">/usr/src/usr.sbin/ppp</filename></userinput>
&prompt.root; <userinput><command>echo</command> <makevar>STRIP</makevar>= >> <filename>/etc/make.conf</filename></userinput>
&prompt.root; <userinput><command>echo</command> <makevar>CFLAGS</makevar>+=<option>-g</option> >> <filename>/etc/make.conf</filename></userinput>
&prompt.root; <userinput><command>make</command> <maketarget>install</maketarget> <maketarget>clean</maketarget></userinput></screen>
<para>You will now have a debuggable version of &man.ppp.8;
installed. You will have to be <username>root</username> to
run &man.ppp.8; as all of its privileges have been revoked.
When you start &man.ppp.8;, take a careful note of what your
current directory was at the time.</para>
<para>Now, if and when &man.ppp.8; receives the segmentation
violation, it will dump a core file called
<filename>ppp.core</filename>. You should then do the
following:</para>
<screen>&prompt.user; <userinput>su</userinput>
&prompt.root; <userinput>gdb /usr/sbin/ppp ppp.core</userinput>
<prompt>(gdb)</prompt> <userinput>bt</userinput>
.....
<prompt>(gdb)</prompt> <userinput>f 0</userinput>
....
<prompt>(gdb)</prompt> <userinput>i args</userinput>
....
<prompt>(gdb)</prompt> <userinput>l</userinput>
.....</screen>
<para>All of this information should be given alongside your
question, making it possible to diagnose the problem.</para>
<para>If you are familiar with &man.gdb.1;, you may wish to
find out some other bits and pieces such as what actually
caused the dump or the addresses and values of the relevant
variables.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-autodialprocess-noconnect">
<para>Why does the process that forces a dial in
<option>-auto</option> mode never connect?</para>
</question>
<answer>
<para>This was a known problem with &man.ppp.8; set up to
negotiate a dynamic local IP number with the peer in
<option>-auto</option> mode. It has been fixed a long time
ago — search the manual page for
<literal>iface</literal>.</para>
<para>The problem was that when that initial program calls
&man.connect.2;, the IP number of the &man.tun.4; interface
is assigned to the socket endpoint. The kernel creates the
first outgoing packet and writes it to the &man.tun.4;
device. &man.ppp.8; then reads the packet and establishes a
connection. If, as a result of &man.ppp.8;'s dynamic IP
assignment, the interface address is changed, the original
socket endpoint will be invalid. Any subsequent packets
sent to the peer will usually be dropped. Even if they are
not, any responses will not route back to the originating
machine as the IP number is no longer owned by that
machine.</para>
<para>There are several theoretical ways to approach this
problem. It would be nicest if the peer would re-assign the
same IP number if possible. The current version of
&man.ppp.8; does this, but most other implementations do
not.</para>
<para>The easiest method from our side would be to never
change the &man.tun.4; interface IP number, but instead to
change all outgoing packets so that the source IP number is
changed from the interface IP to the negotiated IP on the
fly. This is essentially what the
<literal>iface-alias</literal> option in the latest version
of &man.ppp.8; is doing (with the help of &man.libalias.3;
and &man.ppp.8;'s <option>-nat</option> switch) — it
is maintaining all previous interface addresses and NATing
them to the last negotiated address.</para>
<para>Another alternative (and probably the most reliable)
would be to implement a system call that changes all bound
sockets from one IP to another. &man.ppp.8; would use this
call to modify the sockets of all existing programs when a
new IP number is negotiated. The same system call could be
used by <acronym>DHCP</acronym> clients when they are forced
to call the <function>bind()</function> function for their
sockets.</para>
<para>Yet another possibility is to allow an interface to be
brought up without an IP number. Outgoing packets would be
given an IP number of <hostid
role="ipaddr">255.255.255.255</hostid> up until the first
<literal>SIOCAIFADDR</literal> &man.ioctl.2; is done. This
would result in fully binding the socket. It would be up to
&man.ppp.8; to change the source IP number, but only if it
is set to <hostid role="ipaddr">255.255.255.255</hostid>,
and only the IP number and IP checksum would need to change.
This, however is a bit of a hack as the kernel would be
sending bad packets to an improperly configured interface,
on the assumption that some other mechanism is capable of
fixing things retrospectively.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ppp-nat-games">
<para>Why do most games not work with the
<option>-nat</option> switch?</para>
</question>
<answer>
<para>The reason games and the like do not work when
&man.libalias.3; is in use is that the machine on the outside
will try to open a connection or send (unsolicited) UDP
packets to the machine on the inside. The NAT software does
not know that it should send these packets to the interior
machine.</para>
<para>To make things work, make sure that the only thing
running is the software that you are having problems with,
then either run &man.tcpdump.1; on the &man.tun.4; interface
of the gateway or enable &man.ppp.8; TCP/IP logging
(<literal>set log +tcp/ip</literal>) on the gateway.</para>
<para>When you start the offending software, you should see
packets passing through the gateway machine. When something
comes back from the outside, it will be dropped (that is the
problem). Note the port number of these packets then shut
down the offending software. Do this a few times to see if
the port numbers are consistent. If they are, then the
following line in the relevant section of
<filename>/etc/ppp/ppp.conf</filename> will make the
software functional:</para>
<programlisting>nat port <replaceable>proto</replaceable> <replaceable>internalmachine</replaceable>:<replaceable>port</replaceable> <replaceable>port</replaceable></programlisting>
<para>where <replaceable>proto</replaceable> is either
<literal>tcp</literal> or <literal>udp</literal>,
<replaceable>internalmachine</replaceable> is the machine
that you want the packets to be sent to and
<replaceable>port</replaceable> is the destination port
number of the packets.</para>
<para>You will not be able to use the software on other
machines without changing the above command, and running the
software on two internal machines at the same time is out of
the question — after all, the outside world is seeing
your entire internal network as being just a single
machine.</para>
<para>If the port numbers are not consistent, there are three
more options:</para>
<orderedlist>
<listitem>
<para>Submit support in &man.libalias.3;. Examples of
<quote>special cases</quote> can be found in
<filename>/usr/src/sys/netinet/libalias/alias_*.c</filename>
(<filename>alias_ftp.c</filename> is a good prototype).
This usually involves reading certain recognized
outgoing packets, identifying the instruction that tells
the outside machine to initiate a connection back to the
internal machine on a specific (random) port and setting
up a <quote>route</quote> in the alias table so that the
subsequent packets know where to go.</para>
<para>This is the most difficult solution, but it is the
best and will make the software work with multiple
machines.</para>
</listitem>
<listitem>
<para>Use a proxy. The application may support
<literal>socks5</literal> for example, or
may have a
<quote>passive</quote> option that avoids ever
requesting that the peer open connections back to the
local machine.</para>
</listitem>
<listitem>
<para>Redirect everything to the internal machine using
<literal>nat addr</literal>. This is the sledge-hammer
approach.</para>
</listitem>
</orderedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="fcs-errors">
<para>What are FCS errors?</para>
</question>
<answer>
<para>FCS stands for Frame Check Sequence. Each
PPP packet has a checksum attached to ensure that the data
being received is the data being sent. If the FCS of an
incoming packet is incorrect, the packet is dropped and the
HDLC FCS count is increased. The HDLC error values can be
displayed using the <literal>show hdlc</literal>
command.</para>
<para>If your link is bad (or if your serial driver is
dropping packets), you will see the occasional FCS error.
This is not usually worth worrying about although it does
slow down the compression protocols substantially. If you
have an external modem, make sure your cable is properly
shielded from interference — this may eradicate the
problem.</para>
<para>If your link freezes as soon as you have connected and
you see a large number of FCS errors, this may be because your
link is not 8-bit clean. Make sure your modem is not using
software flow control (XON/XOFF). If your datalink
<emphasis>must</emphasis> use software flow control, use the
command <literal>set accmap 0x000a0000</literal> to tell
&man.ppp.8; to escape the <literal>^Q</literal> and
<literal>^S</literal> characters.</para>
<para>Another reason for seeing too many FCS errors may be
that the remote end has stopped talking
<acronym>PPP</acronym>. You may want to enable
<literal>async</literal> logging at this point to determine
if the incoming data is actually a login or shell prompt.
If you have a shell prompt at the remote end, it is possible
to terminate &man.ppp.8; without dropping the line by using
<command>close lcp</command> (a following
<command>term</command>) will reconnect you to the
shell on the remote machine.</para>
<para>If nothing in your log file indicates why the link might
have been terminated, you should ask the remote
administrator (your ISP?) why the session was
terminated.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="desperation">
<para>None of this helps — I am desperate! What can I
do?</para>
</question>
<answer>
<para>If all else fails, send as much information as you can,
including your config files, how you are starting
&man.ppp.8;, the relevant parts of your log file and the
output of <command>netstat -rn</command> (before
and after connecting) to the &a.questions;
and someone should point you in the right
direction.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="serial">
<title>Serial Communications</title>
<para>This section answers common questions about serial
communications with &os;. PPP is covered in the <link
linkend="networking">Networking</link> section.</para>
<qandaset>
<qandaentry>
<question id="multiport-serial-support">
<para>Which multi-port serial cards are supported by
&os;?</para>
</question>
<answer>
<para>There is a list of these in the <ulink
url="&url.books.handbook;/serial.html">Serial Communications</ulink>
chapter of the handbook.</para>
<para>Most multi-port PCI cards that are based on 16550 or
clones are supported with no extra effort.</para>
<para>Some unnamed clone cards have also been known to work,
especially those that claim to be AST compatible.</para>
<para>Check &man.uart.4; and &man.sio.4; to get more
information on configuring such cards.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="serial-console-prompt">
<para>How do I get the boot: prompt to show on the serial
console?</para>
</question>
<answer>
<para>See <ulink
url="&url.books.handbook;/serialconsole-setup.html">this section of the handbook</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="found-serial">
<para>How do I tell if &os; found my serial ports or modem
cards?</para>
</question>
<answer>
<para>As the &os; kernel boots, it will probe for the serial
ports in your system for which the kernel was configured.
You can either watch your system closely for the messages it
prints or run this command after your system is up and
running:</para>
<screen>&prompt.user; <userinput>dmesg | grep -E "^sio[0-9]"</userinput></screen>
<para>Here is some example output from the above
command:</para>
<programlisting>sio0: <16550A-compatible COM port> port 0x3f8-0x3ff irq 4 flags 0x10 on acpi0
sio0: type 16550A
sio1: <16550A-compatible COM port> port 0x2f8-0x2ff irq 3 on acpi0
sio1: type 16550A</programlisting>
<para>This shows two serial ports. The first is on
IRQ 4, is using port address <literal>0x3f8</literal>,
and has a 16550A-type UART chip. The second uses the same
kind of chip but is on IRQ 3 and is at port address
<literal>0x2f8</literal>. Internal modem cards are treated
just like serial ports — except that they always have
a modem <quote>attached</quote> to the port.</para>
<para>The <filename>GENERIC</filename> kernel includes support
for two serial ports using the same IRQ and port address
settings in the above example. If these settings are not
right for your system, or if you have added modem cards or
have more serial ports than your kernel is configured for,
just reconfigure your kernel. See section <link
linkend="make-kernel">about building a kernel</link> for
more details.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="access-serial-ports">
<para>How do I access the serial ports on &os;?</para>
</question>
<answer>
<para>The third serial port, <devicename>sio2</devicename>
(see &man.sio.4;, known as <devicename>COM3</devicename> in
DOS), is on <devicename>/dev/cuad2</devicename> for dial-out
devices, and on <devicename>/dev/ttyd2</devicename> for
dial-in devices. What is the difference between these two
classes of devices?</para>
<para>You use
<devicename>ttyd<replaceable>X</replaceable></devicename>
for dial-ins. When opening
<devicename>/dev/ttyd<replaceable>X</replaceable></devicename>
in blocking mode, a process will wait for the corresponding
<devicename>cuad<replaceable>X</replaceable></devicename>
device to become inactive, and then wait for the carrier
detect line to go active. When you open the
<devicename>cuad<replaceable>X</replaceable></devicename>
device, it makes sure the serial port is not already in use
by the
<devicename>ttyd<replaceable>X</replaceable></devicename>
device. If the port is available, it <quote>steals</quote>
it from the
<devicename>ttyd<replaceable>X</replaceable></devicename>
device. Also, the
<devicename>cuad<replaceable>X</replaceable></devicename>
device does not care about carrier detect. With this scheme
and an auto-answer modem, you can have remote users log in
and you can still dial out with the same modem and the
system will take care of all the conflicts.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="enable-multiport-serial">
<para>How do I enable support for a multiport serial
card?</para>
</question>
<answer>
<para>Again, the section on kernel configuration provides
information about configuring your kernel. For a multiport
serial card, place an &man.sio.4; line for each serial port
on the card in the &man.device.hints.5; file. But place the
IRQ specifiers on only one of the entries. All of the ports
on the card should share one IRQ. For consistency, use the
last serial port to specify the IRQ. Also, specify the
following option in the kernel configuration file:</para>
<programlisting>options COM_MULTIPORT</programlisting>
<para>The following <filename>/boot/device.hints</filename>
example is for an AST 4-port serial card on
IRQ 12:</para>
<programlisting>hint.sio.4.at="isa"
hint.sio.4.port="0x2a0"
hint.sio.4.flags="0x701"
hint.sio.5.at="isa"
hint.sio.5.port="0x2a8"
hint.sio.5.flags="0x701"
hint.sio.6.at="isa"
hint.sio.6.port="0x2b0"
hint.sio.6.flags="0x701"
hint.sio.7.at="isa"
hint.sio.7.port="0x2b8"
hint.sio.7.flags="0x701"
hint.sio.7.irq="12"</programlisting>
<para>The flags indicate that the master port has minor number
<literal>7</literal> (<literal>0x700</literal>), and all the
ports share an IRQ (<literal>0x001</literal>).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="default-serial-params">
<para>Can I set the default serial parameters for a
port?</para>
</question>
<answer>
<para>See the <ulink
url="&url.books.handbook;/serial.html#serial-hw-config">Serial Communications</ulink>
section in the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="enable-dialup">
<para>How can I enable dialup logins on my modem?</para>
</question>
<answer>
<para>Please read the section about <ulink
url="&url.books.handbook;/dialup.html">Dial-in Services</ulink>
in the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="dumb-terminal">
<para>How can I connect a dumb terminal to my &os; box?</para>
</question>
<answer>
<para>You can find this information in the <ulink
url="&url.books.handbook;/term.html">Terminals</ulink>
section of the &os; Handbook.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="cannot-tip">
<para>Why can I not run <command>tip</command> or
<command>cu</command>?</para>
</question>
<answer>
<para>On your system, the programs &man.tip.1; and &man.cu.1;
can only access the <filename class="directory">/var/spool/lock</filename>
directory via user <username>uucp</username> and group
<groupname>dialer</groupname>. You can use the group
<groupname>dialer</groupname> to control who has access to
your modem or remote systems. Just add yourself to group
<groupname>dialer</groupname>.</para>
<para>Alternatively, you can let everyone on your system run
&man.tip.1; and &man.cu.1; by typing:</para>
<screen>&prompt.root; <userinput>chmod 4511 /usr/bin/cu</userinput>
&prompt.root; <userinput>chmod 4511 /usr/bin/tip</userinput></screen>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="misc">
<title>Miscellaneous Questions</title>
<qandaset>
<qandaentry>
<question id="more-swap">
<para>&os; a lot of swap space even when the computer has
free memory left. Why?</para>
</question>
<answer>
<para>&os; will proactively
move entirely idle, unused pages of main memory into swap in
order to make more main memory available for active use.
This heavy use of swap is balanced by using the extra free
memory for cacheing.</para>
<para>Note that while &os; is proactive in this regard, it
does not arbitrarily decide to swap pages when the system is
truly idle. Thus you will not find your system all paged
out when you get up in the morning after leaving it idle
overnight.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="top-freemem">
<para>Why does <command>top</command> show very little free
memory even when I have very few programs running?</para>
</question>
<answer>
<para>The simple answer is that free memory is wasted memory.
Any memory that your programs do not actively allocate is
used within the &os; kernel as disk cache. The values shown
by &man.top.1; labeled as <literal>Inact</literal>,
<literal>Cache</literal>, and <literal>Buf</literal> are all
cached data at different aging levels. This cached data
means the system does not have to access a slow disk again
for data it has accessed recently, thus increasing overall
performance. In general, a low value shown for
<literal>Free</literal> memory in &man.top.1; is good,
provided it is not <emphasis>very</emphasis> low.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="chmod-symlinks">
<para>Why will <command>chmod</command> not change the
permissions on symlinks?</para>
</question>
<answer>
<para>Symlinks do not have permissions, and by default,
&man.chmod.1; will follow symlinks to change the
permissions on the source file, if possible. So if you have a file,
<filename>foo</filename>, and a symlink to that file,
<filename>bar</filename>, then this command will always
succeed.</para>
<screen>&prompt.user; <userinput>chmod g-w bar</userinput></screen>
<para>However, the permissions on <filename>bar</filename>
will not have changed.</para>
<para>When changing modes of the file hierarchies rooted in the
files instead of the files themselves,
you have to use either <option>-H</option> or
<option>-L</option> together with <option>-R</option>
to make this work. See &man.chmod.1; and
&man.symlink.7; for more information.</para>
<warning>
<para><option>-R</option> does a
<emphasis>recursive</emphasis> &man.chmod.1;. Be careful
about specifying directories or symlinks to directories to
&man.chmod.1;. If you want to change the permissions of a
directory referenced by a symlink, use &man.chmod.1;
without any options and follow the symlink with a trailing
slash (<filename class="directory">/</filename>). For example, if
<filename>foo</filename> is a symlink to directory
<filename class="directory">bar</filename>, and you want to change the
permissions of <filename>foo</filename> (actually
<filename class="directory">bar</filename>), you would do something
like:</para>
<screen>&prompt.user; <userinput>chmod 555 foo/</userinput></screen>
<para>With the trailing slash, &man.chmod.1; will follow the
symlink, <filename>foo</filename>, to change the
permissions of the directory,
<filename class="directory">bar</filename>.</para>
</warning>
</answer>
</qandaentry>
<qandaentry>
<question id="dos-binaries">
<para>Can I run DOS binaries under &os;?</para>
</question>
<answer>
<para>Yes, you can use <filename
role="package">emulators/doscmd</filename>, a DOS
emulation program, available in the &os; Ports
Collection.</para>
<para>If <application>doscmd</application> will not suffice,
the add-on utility <filename
role="package">emulators/pcemu</filename> emulates an 8088
and enough BIOS services to run many DOS text mode
applications. It requires the X Window System.</para>
<para>You may also try <filename
role="package">emulators/dosbox</filename> from the &os;
Ports Collection. The main focus of this application is
emulating old DOS games using the local file system for
files.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="translation">
<para>What do I need to do to translate a &os; document into
my native language?</para>
</question>
<answer>
<para>See the <ulink
url="&url.books.fdp-primer;/translations.html">Translation FAQ</ulink>
in the &os; Documentation Project Primer.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="freebsd-mail-bounces">
<para>Why does my email to any address at <hostid
role="domainname">FreeBSD.org</hostid> bounce?</para>
</question>
<answer>
<para>The <hostid role="domainname">FreeBSD.org</hostid> mail
system implements some of the stricter
<application>Postfix</application> checks on incoming mail
and rejects mail that is either misconfigured or is
potential spam. Your mail might bounce for one of the
following reasons:</para>
<itemizedlist>
<listitem>
<para>The email is being sent from a known spam domain or
IP block.</para>
<para>The &os; mail servers reject email from known spam
sources. If you have service through a company or
domain who generates or relays spam, please switch to a
service provider who does not.</para>
</listitem>
<listitem>
<para>The body of the email only contains HTML.</para>
<para>Mail should be sent in plain text only. Please
configure your mail user agent to send plain
text.</para>
</listitem>
<listitem>
<para>The mailer at <hostid
role="domainname">FreeBSD.org</hostid> cannot resolve
the IP address of the connecting host back to a
symbolic name.</para>
<para>Working reverse DNS is a standard requirement for
accepting mail from a host. Set up reverse DNS for your
mail server's IP address. Many home services (DSL,
cable, dialup, etc.) will not give you this option. In
this case, relay your email through your service
provider's mail server.</para>
</listitem>
<listitem>
<para>The hostname given in the EHLO/HELO part of the SMTP
exchange cannot be resolved to an IP address.</para>
<para>A fully qualified, resolvable host name is necessary
in this part of the SMTP dialogue before mail will be
accepted. If you do not have a host name that is
registered in the DNS, then you should use your service
provider's mail server to relay your mail.</para>
</listitem>
<listitem>
<para>Your message had a message ID ending with the string
<quote>localhost</quote>.</para>
<para>Some mail user agents generate bad message IDs which
will not be accepted. You will need to persuade your mail
user agent to generate a valid message ID or else
configure your mail transfer agent to rewrite
them.</para>
</listitem>
</itemizedlist>
</answer>
</qandaentry>
<qandaentry>
<question id="free-account">
<para>Where can I find a free &os; account?</para>
</question>
<answer>
<para>While &os; does not provide open access to any of their
servers, others do provide open access &unix; systems. The
charge varies and limited services may be available.</para>
<para><ulink
url="http://www.arbornet.org/">Arbornet, Inc</ulink>,
also known as <emphasis>M-Net</emphasis>, has been providing
open access to &unix; systems since 1983. Starting on an
Altos running System III, the site switched to BSD/OS in
1991. In June of 2000, the site switched again to &os;.
<emphasis>M-Net</emphasis> can be accessed via
<application>telnet</application> and
<application>SSH</application> and provides basic access to
the entire &os; software suite. However, network access is
limited to members and patrons who donate to the system,
which is run as a non-profit organization.
<emphasis>M-Net</emphasis> also provides an bulletin board
system and interactive chat.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="daemon-name">
<para>What is the cute little red guy's name?</para>
</question>
<answer>
<para>He does not have one, and is just called <quote>the BSD
daemon</quote>. If you insist upon using a name, call him
<quote>beastie</quote>. Note that <quote>beastie</quote> is
pronounced <quote>BSD</quote>.</para>
<para>You can learn more about the BSD daemon on his <ulink
url="http://www.mckusick.com/beastie/index.html">home page</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="use-beastie">
<para>Can I use the BSD daemon image?</para>
</question>
<answer>
<para>Perhaps. The BSD daemon is copyrighted by Marshall Kirk
McKusick. You will want to check his <ulink
url="http://www.mckusick.com/beastie/mainpage/copyright.html">Statement on the Use of the BSD Daemon Figure</ulink>
for detailed usage terms.</para>
<para>In summary, you are free to use the image in a tasteful
manner, for personal use, so long as appropriate credit is
given. If you want to use him commercially, you must
contact &a.mckusick;. More details are available on the
<ulink
url="http://www.mckusick.com/beastie/index.html">BSD Daemon's home page</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="daemon-images">
<para>Do you have any BSD daemon images I could use?</para>
</question>
<answer>
<para>You will find eps and Xfig drawings under
<filename class="directory">/usr/share/examples/BSD_daemon/</filename>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="glossary">
<para>I have seen an acronym or other term on the mailing
lists and I do not understand what it means. Where should I
look?</para>
</question>
<answer>
<para>Please see the <ulink
url="&url.books.handbook;/freebsd-glossary.html">&os; Glossary</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="bikeshed-painting">
<para>Why should I care what color the bikeshed is?</para>
</question>
<answer>
<para>The really, really short answer is that you should not.
The somewhat longer answer is that just because you are
capable of building a bikeshed does not mean you should stop
others from building one just because you do not like the
color they plan to paint it. This is a metaphor indicating
that you need not argue about every little feature just
because you know enough to do so. Some people have
commented that the amount of noise generated by a change is
inversely proportional to the complexity of the
change.</para>
<para>The longer and more complete answer is that after a very
long argument about whether &man.sleep.1; should take
fractional second arguments, &a.phk; posted a long message
entitled <quote><ulink
url="http://www.FreeBSD.org/cgi/getmsg.cgi?fetch=506636+517178+/usr/local/www/db/text/1999/freebsd-hackers/19991003.freebsd-hackers">A bike shed (any color will do) on greener grass...</ulink></quote>.
The appropriate portions of that message are quoted
below.</para>
<blockquote>
<attribution>&a.phk; on &a.hackers.name;, October 2,
1999</attribution>
<para><quote>What is it about this bike shed?</quote> Some
of you have asked me.</para>
<para>It is a long story, or rather it is an old story, but
it is quite short actually. C. Northcote Parkinson wrote
a book in the early 1960s, called <quote>Parkinson's
Law</quote>, which contains a lot of insight into the
dynamics of management.</para>
<para><emphasis>[snip a bit of commentary on the
book]</emphasis></para>
<para>In the specific example involving the bike shed, the
other vital component is an atomic power-plant, I guess
that illustrates the age of the book.</para>
<para>Parkinson shows how you can go into the board of
directors and get approval for building a multi-million or
even billion dollar atomic power plant, but if you want to
build a bike shed you will be tangled up in endless
discussions.</para>
<para>Parkinson explains that this is because an atomic
plant is so vast, so expensive and so complicated that
people cannot grasp it, and rather than try, they fall
back on the assumption that somebody else checked all the
details before it got this far. Richard P. Feynmann
gives a couple of interesting, and very much to the point,
examples relating to Los Alamos in his books.</para>
<para>A bike shed on the other hand. Anyone can build one
of those over a weekend, and still have time to watch the
game on TV. So no matter how well prepared, no matter how
reasonable you are with your proposal, somebody will seize
the chance to show that he is doing his job, that he is
paying attention, that he is
<emphasis>here</emphasis>.</para>
<para>In Denmark we call it <quote>setting your
fingerprint</quote>. It is about personal pride and
prestige, it is about being able to point somewhere and
say <quote>There! <emphasis>I</emphasis> did
that.</quote> It is a strong trait in politicians, but
present in most people given the chance. Just think about
footsteps in wet cement.</para>
</blockquote>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="funnies">
<title>The &os; Funnies</title>
<qandaset>
<qandaentry>
<question id="very-very-cool">
<para>How cool is &os;?</para>
</question>
<answer>
<para>Q. Has anyone done any temperature testing while
running &os;? I know &linux; runs cooler than DOS, but have
never seen a mention of &os;. It seems to run really
hot.</para>
<para>A. No, but we have done numerous taste tests on
blindfolded volunteers who have also had 250 micrograms of
LSD-25 administered beforehand. 35% of the volunteers said
that &os; tasted sort of orange, whereas &linux; tasted like
purple haze. Neither group mentioned any significant
variances in temperature. We eventually had to throw the
results of this survey out entirely anyway when we found
that too many volunteers were wandering out of the room
during the tests, thus skewing the results. We think most
of the volunteers are at Apple now, working on their new
<quote>scratch and sniff</quote> GUI. It is a funny old
business we are in!</para>
<para>Seriously, &os; uses the
<acronym>HLT</acronym> (halt) instruction when the system is
idle thus lowering its energy consumption and therefore the
heat it generates. Also if you have
<acronym>ACPI</acronym> (Advanced
Configuration and Power Interface)
configured, then &os; can also put the CPU into
a low power mode.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="letmeoutofhere">
<para>Who is scratching in my memory banks??</para>
</question>
<answer>
<para>Q. Is there anything <quote>odd</quote> that &os; does
when compiling the kernel which would cause the memory to
make a scratchy sound? When compiling (and for a brief
moment after recognizing the floppy drive upon startup, as
well), a strange scratchy sound emanates from what appears
to be the memory banks.</para>
<para>A. Yes! You will see frequent references to
<quote>daemons</quote> in the BSD documentation, and what
most people do not know is that this refers to genuine,
non-corporeal entities that now possess your computer. The
scratchy sound coming from your memory is actually
high-pitched whispering exchanged among the daemons as they
best decide how to deal with various system administration
tasks.</para>
<para>If the noise gets to you, a good
<command>fdisk /mbr</command> from DOS will get rid of them,
but do not be surprised if they react adversely and try to
stop you. In fact, if at any point during the exercise you
hear the satanic voice of Bill Gates coming from the
built-in speaker, take off running and do not ever look
back! Freed from the counterbalancing influence of the BSD
daemons, the twin demons of DOS and &windows; are often able
to re-assert total control over your machine to the eternal
damnation of your soul. Now that you know, given a choice
you would probably prefer to get used to the scratchy
noises, no?</para>
</answer>
</qandaentry>
<qandaentry>
<question id="changing-lightbulbs">
<para>How many &os; hackers does it take to change a
lightbulb?</para>
</question>
<answer>
<para>One thousand, one hundred and sixty-nine:</para>
<para>Twenty-three to complain to -CURRENT about the lights
being out;</para>
<para>Four to claim that it is a configuration problem, and
that such matters really belong on -questions;</para>
<para>Three to submit PRs about it, one of which is misfiled
under doc and consists only of <quote>it's
dark</quote>;</para>
<para>One to commit an untested lightbulb which breaks
buildworld, then back it out five minutes later;</para>
<para>Eight to flame the PR originators for not including
patches in their PRs;</para>
<para>Five to complain about buildworld being broken;</para>
<para>Thirty-one to answer that it works for them, and they
must have updated at a bad time;</para>
<para>One to post a patch for a new lightbulb to
-hackers;</para>
<para>One to complain that he had patches for this three years
ago, but when he sent them to -CURRENT they were just
ignored, and he has had bad experiences with the PR system;
besides, the proposed new lightbulb is non-reflexive;</para>
<para>Thirty-seven to scream that lightbulbs do not belong in
the base system, that committers have no right to do things
like this without consulting the Community, and WHAT IS
-CORE DOING ABOUT IT!?</para>
<para>Two hundred to complain about the color of the bicycle
shed;</para>
<para>Three to point out that the patch breaks
&man.style.9;;</para>
<para>Seventeen to complain that the proposed new lightbulb is
under GPL;</para>
<para>Five hundred and eighty-six to engage in a flame war
about the comparative advantages of the GPL, the BSD
license, the MIT license, the NPL, and the personal hygiene
of unnamed FSF founders;</para>
<para>Seven to move various portions of the thread to -chat
and -advocacy;</para>
<para>One to commit the suggested lightbulb, even though it
shines dimmer than the old one;</para>
<para>Two to back it out with a furious flame of a commit
message, arguing that &os; is better off in the dark than
with a dim lightbulb;</para>
<para>Forty-six to argue vociferously about the backing out of
the dim lightbulb and demanding a statement from
-core;</para>
<para>Eleven to request a smaller lightbulb so it will fit
their Tamagotchi if we ever decide to port &os; to that
platform;</para>
<para>Seventy-three to complain about the SNR on -hackers and
-chat and unsubscribe in protest;</para>
<para>Thirteen to post <quote>unsubscribe</quote>, <quote>How
do I unsubscribe?</quote>, or <quote>Please remove me from
the list</quote>, followed by the usual footer;</para>
<para>One to commit a working lightbulb while everybody is too
busy flaming everybody else to notice;</para>
<para>Thirty-one to point out that the new lightbulb would
shine 0.364% brighter if compiled with TenDRA (although it
will have to be reshaped into a cube), and that &os; should
therefore switch to TenDRA instead of GCC;</para>
<para>One to complain that the new lightbulb lacks
fairings;</para>
<para>Nine (including the PR originators) to ask <quote>what
is MFC?</quote>;</para>
<para>Fifty-seven to complain about the lights being out two
weeks after the bulb has been changed.</para>
<para><emphasis>&a.nik; adds:</emphasis></para>
<para><emphasis>I was laughing quite hard at
this.</emphasis></para>
<para><emphasis>And then I thought, <quote>Hang on, shouldn't
there be '1 to document it.' in that list
somewhere?</quote></emphasis></para>
<para><emphasis>And then I was enlightened
:-)</emphasis></para>
<para><emphasis>&a.tabthorpe;</emphasis> says: <quote>None,
<emphasis>real</emphasis> &os; hackers are not afraid of the
dark!</quote></para>
</answer>
</qandaentry>
<qandaentry>
<question id="dev-null">
<para>Where does data written to
<filename>/dev/null</filename> go?</para>
</question>
<answer>
<para>It goes into a special data sink in the CPU where it is
converted to heat which is vented through the heatsink / fan
assembly. This is why CPU cooling is increasingly
important; as people get used to faster processors, they
become careless with their data and more and more of it ends
up in <filename>/dev/null</filename>, overheating their
CPUs. If you delete <filename>/dev/null</filename> (which
effectively disables the CPU data sink) your CPU may run
cooler but your system will quickly become constipated with
all that excess data and start to behave erratically. If
you have a fast network connection you can cool down your
CPU by reading data out of <filename>/dev/random</filename>
and sending it off somewhere; however you run the risk of
overheating your network connection and
<filename class="directory">/</filename> or angering your ISP, as most of the
data will end up getting converted to heat by their
equipment, but they generally have good cooling, so if you
do not overdo it you should be OK.</para>
<para><emphasis>Paul Robinson adds:</emphasis></para>
<para>There are other methods. As every good sysadmin knows,
it is part of standard practice to send data to the screen
of interesting variety to keep all the pixies that make up
your picture happy. Screen pixies (commonly mis-typed or
re-named as <quote>pixels</quote>) are categorized by the
type of hat they wear (red, green or blue) and will hide or
appear (thereby showing the color of their hat) whenever
they receive a little piece of food. Video cards turn data
into pixie-food, and then send them to the pixies —
the more expensive the card, the better the food, so the
better behaved the pixies are. They also need constant
stimulation — this is why screen savers exist.</para>
<para>To take your suggestions further, you could just throw
the random data to console, thereby letting the pixies
consume it. This causes no heat to be produced at all,
keeps the pixies happy and gets rid of your data quite
quickly, even if it does make things look a bit messy on
your screen.</para>
<para>Incidentally, as an ex-admin of a large ISP who
experienced many problems attempting to maintain a stable
temperature in a server room, I would strongly discourage
people sending the data they do not want out to the network.
The fairies who do the packet switching and routing get
annoyed by it as well.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="punk-my-friend">
<para>My colleague sits at the computer too much, how
can I prank her?</para>
</question>
<answer>
<para>Install <filename role="port">games/sl</filename> and wait
for her to mistype <userinput>sl</userinput> for
<command>ls</command>.</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="advanced">
<title>Advanced Topics</title>
<qandaset>
<qandaentry>
<question id="learn-advanced">
<para>How can I learn more about &os;'s internals?</para>
</question>
<answer>
<para>See the
<ulink
url="&url.books.arch-handbook;">&os; Architecture Handbook</ulink>.</para>
<para>Additionally, much general &unix; knowledge is directly
applicable to &os;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="how-to-contribute">
<para>How can I contribute to &os;?</para>
</question>
<answer>
<para>Please see the article on <ulink
url="&url.articles.contributing;/article.html">Contributing to &os;</ulink>
for specific advice on how to do this. Assistance is more
than welcome!</para>
</answer>
</qandaentry>
<qandaentry>
<question id="define-snap-release">
<para>What are snapshots and releases?</para>
</question>
<answer>
<para>There are currently four active/semi-active branches in
the &os; <ulink
url="http://svnweb.FreeBSD.org/base/">Subversion Repository</ulink>.
(Earlier branches are only changed very rarely, which is why
there are only four active branches of development):</para>
<itemizedlist>
<listitem>
<para>&rel3.releng; AKA
&rel3.stable;</para>
</listitem>
<listitem>
<para>&rel2.releng; AKA
&rel2.stable;</para>
</listitem>
<listitem>
<para>&rel.releng; AKA
&rel.stable;</para>
</listitem>
<listitem>
<para>&rel.head.releng; AKA
<emphasis>-CURRENT</emphasis> AKA
&rel.head;</para>
</listitem>
</itemizedlist>
<para><literal>HEAD</literal> is not an actual branch tag,
like the others; it is simply a symbolic constant for
<quote><emphasis>the current, non-branched development
stream</emphasis></quote> which we simply refer to as
<emphasis>-CURRENT</emphasis>.</para>
<para>Right now, <emphasis>-CURRENT</emphasis> is the
&rel.head.relx; development stream; the
&rel.stable; branch,
&rel.releng;, forked off from
<emphasis>-CURRENT</emphasis> in &rel.relengdate; and the
&rel2.stable; branch,
&rel2.releng;, forked off from
<emphasis>-CURRENT</emphasis> in &rel2.relengdate;.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="ctm">
<para>Can I follow <emphasis>-CURRENT</emphasis> with limited
Internet access?</para>
</question>
<answer>
<para>Yes, you can do this <emphasis>without</emphasis>
downloading the whole source tree by using the <ulink
url="&url.books.handbook;/synching.html#ctm">CTM facility</ulink>.</para>
</answer>
</qandaentry>
<qandaentry>
<question id="submitting-kernel-extensions">
<para>I have written a kernel extension, who do I send it
to?</para>
</question>
<answer>
<para>Please take a look at the article on <ulink
url="&url.articles.contributing;/article.html">Contributing to &os;</ulink>
to learn how to submit code.</para>
<para>And thanks for the thought!</para>
</answer>
</qandaentry>
<qandaentry>
<question id="kernel-panic-troubleshooting">
<para>How can I make the most of the data I see when my kernel
panics?</para>
</question>
<answer>
<para>Here is typical kernel panic:</para>
<programlisting>Fatal trap 12: page fault while in kernel mode
fault virtual address = 0x40
fault code = supervisor read, page not present
instruction pointer = 0x8:0xf014a7e5
stack pointer = 0x10:0xf4ed6f24
frame pointer = 0x10:0xf4ed6f28
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 80 (mount)
interrupt mask =
trap number = 12
panic: page fault</programlisting>
<para>When you see a message like this, it is not enough to
just reproduce it and send it in. The instruction pointer
value is important;
unfortunately, it is also configuration dependent. In other
words, the value varies depending on the exact kernel image
that you are using. If you are using a
<filename>GENERIC</filename> kernel image from one of the
snapshots, then it is possible for somebody else to track
down the offending function, but if you are running a custom
kernel then only <emphasis>you</emphasis> can tell us where
the fault occurred.</para>
<para>What you should do is this:</para>
<procedure>
<step>
<para>Write down the instruction pointer value. Note
that the <literal>0x8:</literal> part at the beginning
is not significant in this case: it is the
<literal>0xf0xxxxxx</literal> part that we
want.</para>
</step>
<step>
<para>When the system reboots, do the following:</para>
<screen>&prompt.user; <userinput><command>nm</command> <option>-n</option> <replaceable>kernel.that.caused.the.panic</replaceable> | <command>grep</command> f0xxxxxx</userinput></screen>
<para>where <literal>f0xxxxxx</literal> is the
instruction pointer value. The odds are you will not
get an exact match since the symbols in the kernel
symbol table are for the entry points of functions and
the instruction pointer address will be somewhere
inside a function, not at the start. If you do not
get an exact match, omit the last digit from the
instruction pointer value and try again, i.e.:</para>
<screen>&prompt.user; <userinput><command>nm</command> <option>-n</option> <replaceable>kernel.that.caused.the.panic</replaceable> | <command>grep</command> f0xxxxx</userinput></screen>
<para>If that does not yield any results, chop off another
digit. Repeat until you get some sort of output. The
result will be a possible list of functions which caused
the panic. This is a less than exact mechanism for
tracking down the point of failure, but it is better
than nothing.</para>
</step>
</procedure>
<para>However, the best way to track down the cause of a panic
is by capturing a crash dump, then using &man.kgdb.1; to
generate a stack trace on the crash dump.</para>
<para>In any case, the method is this:</para>
<procedure>
<step>
<para>Make sure that the following line is included in
your kernel configuration file
(<filename>/usr/src/sys/<replaceable>arch</replaceable>/conf/<replaceable>MYKERNEL</replaceable></filename>):</para>
<programlisting>makeoptions DEBUG=-g # Build kernel with gdb(1) debug symbols</programlisting>
</step>
<step>
<para>Change to the <filename
class="directory">/usr/src</filename>
directory:</para>
<screen>&prompt.root; <userinput><command>cd</command> <filename class="directory">/usr/src</filename></userinput></screen>
</step>
<step>
<para>Compile the kernel:</para>
<screen>&prompt.root; <userinput><command>make</command> <maketarget>buildkernel</maketarget> <makevar>KERNCONF</makevar>=<replaceable>MYKERNEL</replaceable></userinput></screen>
</step>
<step>
<para>Wait for &man.make.1; to finish compiling.</para>
</step>
<step>
<screen>&prompt.root; <userinput><command>make</command> <maketarget>installkernel</maketarget> <makevar>KERNCONF</makevar>=<replaceable>MYKERNEL</replaceable></userinput></screen>
</step>
<step>
<para>Reboot.</para>
</step>
</procedure>
<note>
<para>If you do not use the <makevar>KERNCONF</makevar>
make variable a <filename>GENERIC</filename> kernel will
be built and installed.</para>
</note>
<para>The &man.make.1; process will have built two kernels.
<filename>/usr/obj/usr/src/sys/<replaceable>MYKERNEL</replaceable>/kernel</filename>
and
<filename>/usr/obj/usr/src/sys/<replaceable>MYKERNEL</replaceable>/kernel.debug</filename>.
<filename>kernel</filename> was installed as
<filename>/boot/kernel/kernel</filename>, while
<filename>kernel.debug</filename> can be used as the source
of debugging symbols for &man.kgdb.1;.</para>
<para>To make sure you capture a crash dump, you need edit
<filename>/etc/rc.conf</filename> and set
<literal>dumpdev</literal> to point to your swap partition
(or <literal>AUTO</literal>). This will cause the
&man.rc.8; scripts to use the &man.dumpon.8; command to
enable crash dumps. You can also run &man.dumpon.8;
manually. After a panic, the crash dump can be recovered
using &man.savecore.8;; if <literal>dumpdev</literal> is set
in <filename>/etc/rc.conf</filename>, the &man.rc.8; scripts
will run &man.savecore.8; automatically and put the crash
dump in <filename class="directory">/var/crash</filename>.</para>
<note>
<para>&os; crash dumps are usually the same size as the
physical RAM size of your machine. That is, if you have
512 MB of RAM, you will get a 512 MB crash dump.
Therefore you must make sure there is enough space in
<filename class="directory">/var/crash</filename> to hold the dump.
Alternatively, you run &man.savecore.8; manually and have
it recover the crash dump to another directory where you
have more room. It is possible to limit the size of the
crash dump by using <literal>options
MAXMEM=<replaceable>N</replaceable></literal> where
<replaceable>N</replaceable> is the size of kernel's
memory usage in KBs. For example, if you have 1 GB
of RAM, you can limit the kernel's memory usage to
128 MB by this way, so that your crash dump size will
be 128 MB instead of 1 GB.</para>
</note>
<para>Once you have recovered the crash dump, you can get a
stack trace with &man.kgdb.1; as follows:</para>
<screen>&prompt.user; <userinput><command>kgdb</command> <filename>/usr/obj/usr/src/sys/<replaceable>MYKERNEL</replaceable>/kernel.debug</filename> <filename class="directory">/var/crash/<replaceable>vmcore.0</replaceable></filename></userinput>
<prompt>(kgdb)</prompt> <userinput>backtrace</userinput></screen>
<para>Note that there may be several screens worth of
information; ideally you should use &man.script.1; to
capture all of them. Using the unstripped kernel image with
all the debug symbols should show the exact line of kernel
source code where the panic occurred. Usually you have to
read the stack trace from the bottom up to trace
the exact sequence of events that lead to the crash. You
can also use &man.kgdb.1; to print out the contents of
various variables or structures to examine the
system state at the time of the crash.</para>
<tip>
<para>Now, if you are really insane and have a second
computer, you can also configure &man.kgdb.1; to do remote
debugging such that you can use &man.kgdb.1; on one system
to debug the kernel on another system, including setting
breakpoints, single-stepping through the kernel code, just
like you can do with a normal user-mode program.</para>
</tip>
<note>
<para>If you have <literal>DDB</literal> enabled and the
kernel drops into the debugger, you can force a panic (and
a crash dump) just by typing <literal>panic</literal> at
the <literal>ddb</literal> prompt. It may stop in the
debugger again during the panic phase. If it does, type
<literal>continue</literal> and it will finish the crash
dump.</para>
</note>
</answer>
</qandaentry>
<qandaentry>
<question id="dlsym-failure">
<para>Why has <function>dlsym()</function> stopped working for
ELF executables?</para>
</question>
<answer>
<para>The ELF toolchain does not, by default, make the symbols
defined in an executable visible to the dynamic linker.
Consequently <function>dlsym()</function> searches on
handles obtained from calls to <function>dlopen(NULL,
flags)</function> will fail to find such symbols.</para>
<para>If you want to search, using
<function>dlsym()</function>, for symbols present in the
main executable of a process, you need to link the
executable using the <option>--export-dynamic</option>
option to the ELF linker (&man.ld.1;).</para>
</answer>
</qandaentry>
<qandaentry>
<question id="change-kernel-address-space">
<para>How can I increase or reduce the kernel address space on
i386?</para>
</question>
<answer>
<para>By default, the kernel address space is 1 GB
(2 GB for PAE) for i386. If you run a
network-intensive server (e.g., a FTP or HTTP server),
or you want to use ZFS, you might find that is not
enough.</para>
<para>Add the following line to your kernel configuration file
to increase available space and rebuild your kernel:</para>
<programlisting>options KVA_PAGES=<replaceable>N</replaceable></programlisting>
<para>To find the correct value of
<replaceable>N</replaceable>, divide the desired address
space size (in megabytes) by four. (For example, it is
<literal>512</literal> for 2 GB.)</para>
</answer>
</qandaentry>
</qandaset>
</chapter>
<chapter id="acknowledgments">
<title>Acknowledgments</title>
<para>This innocent little Frequently Asked Questions document has
been written, rewritten, edited, folded, spindled, mutilated,
eviscerated, contemplated, discombobulated, cogitated,
regurgitated, rebuilt, castigated, and reinvigorated over the last
decade, by a cast of hundreds if not thousands.
Repeatedly.</para>
<para>We wish to thank every one of the people responsible, and we
encourage you to <ulink
url="&url.articles.contributing;/article.html">join them</ulink>
in making this FAQ even better.</para>
</chapter>
&bibliography;
</book>