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doc/en_US.ISO8859-1/books/handbook/advanced-networking/chapter.sgml
Glen Barber 0e3359406f Correct a few entries that were mistakenly changed which would adversely 
affect users of 8.x and prior by noting separate rc.conf(5) entries for
8.x and earlier or 9.x and later.

Spotted by:	dougb
Pointyhat to:	gjb (myself)
2012-07-15 07:36:14 +00:00

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<!--
The FreeBSD Documentation Project
$FreeBSD$
-->
<chapter id="advanced-networking">
<title>Advanced Networking</title>
<sect1 id="advanced-networking-synopsis">
<title>Synopsis</title>
<para>This chapter will cover a number of advanced networking
topics.</para>
<para>After reading this chapter, you will know:</para>
<itemizedlist>
<listitem>
<para>The basics of gateways and routes.</para>
</listitem>
<listitem>
<para>How to set up &ieee; 802.11 and &bluetooth;
devices.</para>
</listitem>
<listitem>
<para>How to make FreeBSD act as a bridge.</para>
</listitem>
<listitem>
<para>How to set up network booting on a diskless
machine.</para>
</listitem>
<listitem>
<para>How to set up network PXE booting with an NFS root file
system.</para>
</listitem>
<listitem>
<para>How to set up network address translation.</para>
</listitem>
<listitem>
<para>How to connect two computers via PLIP.</para>
</listitem>
<listitem>
<para>How to set up IPv6 on a FreeBSD machine.</para>
</listitem>
<listitem>
<para>How to configure ATM.</para>
</listitem>
<listitem>
<para>How to enable and utilize the features of CARP, the
Common Address Redundancy Protocol in &os;</para>
</listitem>
</itemizedlist>
<para>Before reading this chapter, you should:</para>
<itemizedlist>
<listitem>
<para>Understand the basics of the
<filename>/etc/rc</filename> scripts.</para>
</listitem>
<listitem>
<para>Be familiar with basic network terminology.</para>
</listitem>
<listitem>
<para>Know how to configure and install a new FreeBSD kernel
(<xref linkend="kernelconfig">).</para>
</listitem>
<listitem>
<para>Know how to install additional third-party
software (<xref linkend="ports">).</para>
</listitem>
</itemizedlist>
</sect1>
<sect1 id="network-routing">
<sect1info>
<authorgroup>
<author>
<firstname>Coranth</firstname>
<surname>Gryphon</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Gateways and Routes</title>
<indexterm><primary>routing</primary></indexterm>
<indexterm><primary>gateway</primary></indexterm>
<indexterm><primary>subnet</primary></indexterm>
<para>For one machine to be able to find another over a network,
there must be a mechanism in place to describe how to get from
one to the other. This is called
<firstterm>routing</firstterm>. A <quote>route</quote> is a
defined pair of addresses: a <quote>destination</quote> and a
<quote>gateway</quote>. The pair indicates that if you are
trying to get to this <emphasis>destination</emphasis>,
communicate through this <emphasis>gateway</emphasis>. There
are three types of destinations: individual hosts, subnets, and
<quote>default</quote>. The <quote>default route</quote> is
used if none of the other routes apply. We will talk a little
bit more about default routes later on. There are also three
types of gateways: individual hosts, interfaces (also called
<quote>links</quote>), and Ethernet hardware addresses (MAC
addresses).</para>
<sect2>
<title>An Example</title>
<para>To illustrate different aspects of routing, we will use
the following example from <command>netstat</command>:</para>
<screen>&prompt.user; <userinput>netstat -r</userinput>
Routing tables
Destination Gateway Flags Refs Use Netif Expire
default outside-gw UGSc 37 418 ppp0
localhost localhost UH 0 181 lo0
test0 0:e0:b5:36:cf:4f UHLW 5 63288 ed0 77
10.20.30.255 link#1 UHLW 1 2421
example.com link#1 UC 0 0
host1 0:e0:a8:37:8:1e UHLW 3 4601 lo0
host2 0:e0:a8:37:8:1e UHLW 0 5 lo0 =>
host2.example.com link#1 UC 0 0
224 link#1 UC 0 0</screen>
<indexterm><primary>default route</primary></indexterm>
<para>The first two lines specify the default route (which we
will cover in the
<link linkend="network-routing-default">next section</link>)
and the <hostid>localhost</hostid> route.</para>
<indexterm><primary>loopback device</primary></indexterm>
<para>The interface (<literal>Netif</literal> column) that this
routing table specifies to use for
<literal>localhost</literal> is <devicename>lo0</devicename>,
also known as the loopback device. This says to keep all
traffic for this destination internal, rather than sending it
out over the LAN, since it will only end up back where it
started.</para>
<indexterm>
<primary>Ethernet</primary>
<secondary>MAC address</secondary>
</indexterm>
<para>The next thing that stands out are the addresses beginning
with <hostid role="mac">0:e0:</hostid>. These are Ethernet
hardware addresses, which are also known as MAC addresses.
FreeBSD will automatically identify any hosts
(<hostid>test0</hostid> in the example) on the local Ethernet
and add a route for that host, directly to it over the
Ethernet interface, <devicename>ed0</devicename>. There is
also a timeout (<literal>Expire</literal> column) associated
with this type of route, which is used if we fail to hear from
the host in a specific amount of time. When this happens, the
route to this host will be automatically deleted. These hosts
are identified using a mechanism known as RIP (Routing
Information Protocol), which figures out routes to local hosts
based upon a shortest path determination.</para>
<indexterm><primary>subnet</primary></indexterm>
<para>FreeBSD will also add subnet routes for the local subnet
(<hostid role="ipaddr">10.20.30.255</hostid> is the broadcast
address for the subnet
<hostid role="ipaddr">10.20.30</hostid>, and
<hostid role="domainname">example.com</hostid> is the domain
name associated with that subnet). The designation
<literal>link#1</literal> refers to the first Ethernet card in
the machine. You will notice no additional interface is
specified for those.</para>
<para>Both of these groups (local network hosts and local
subnets) have their routes automatically configured by a
daemon called <application>routed</application>. If this is
not run, then only routes which are statically defined (i.e.,
entered explicitly) will exist.</para>
<para>The <literal>host1</literal> line refers to our host,
which it knows by Ethernet address. Since we are the sending
host, FreeBSD knows to use the loopback interface
(<devicename>lo0</devicename>) rather than sending it out over
the Ethernet interface.</para>
<para>The two <literal>host2</literal> lines are an example of
what happens when we use an &man.ifconfig.8; alias (see the
section on Ethernet for reasons why we would do this). The
<literal>=&gt;</literal> symbol after the
<devicename>lo0</devicename> interface says that not only are
we using the loopback (since this address also refers to the
local host), but specifically it is an alias. Such routes
only show up on the host that supports the alias; all other
hosts on the local network will simply have a
<literal>link#1</literal> line for such routes.</para>
<para>The final line (destination subnet
<hostid role="ipaddr">224</hostid>) deals with multicasting,
which will be covered in another section.</para>
<para>Finally, various attributes of each route can be seen in
the <literal>Flags</literal> column. Below is a short table
of some of these flags and their meanings:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<colspec colwidth="1*">
<colspec colwidth="4*">
<tbody>
<row>
<entry>U</entry>
<entry>Up: The route is active.</entry>
</row>
<row>
<entry>H</entry>
<entry>Host: The route destination is a single
host.</entry>
</row>
<row>
<entry>G</entry>
<entry>Gateway: Send anything for this destination on to
this remote system, which will figure out from there
where to send it.</entry>
</row>
<row>
<entry>S</entry>
<entry>Static: This route was configured manually, not
automatically generated by the system.</entry>
</row>
<row>
<entry>C</entry>
<entry>Clone: Generates a new route based upon this
route for machines we connect to. This type of route
is normally used for local networks.</entry>
</row>
<row>
<entry>W</entry>
<entry>WasCloned: Indicated a route that was
auto-configured based upon a local area network
(Clone) route.</entry>
</row>
<row>
<entry>L</entry>
<entry>Link: Route involves references to Ethernet
hardware.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</sect2>
<sect2 id="network-routing-default">
<title>Default Routes</title>
<indexterm><primary>default route</primary></indexterm>
<para>When the local system needs to make a connection to a
remote host, it checks the routing table to determine if a
known path exists. If the remote host falls into a subnet
that we know how to reach (Cloned routes), then the system
checks to see if it can connect along that interface.</para>
<para>If all known paths fail, the system has one last option:
the <quote>default</quote> route. This route is a special
type of gateway route (usually the only one present in the
system), and is always marked with a <literal>c</literal> in
the flags field. For hosts on a local area network, this
gateway is set to whatever machine has a direct connection to
the outside world (whether via PPP link, DSL, cable modem, T1,
or another network interface).</para>
<para>If you are configuring the default route for a machine
which itself is functioning as the gateway to the outside
world, then the default route will be the gateway machine at
your Internet Service Provider's (ISP) site.</para>
<para>Let us look at an example of default routes. This is a
common configuration:</para>
<mediaobject>
<imageobject>
<imagedata fileref="advanced-networking/net-routing">
</imageobject>
<textobject>
<literallayout class="monospaced">
[Local2] &lt;--ether--&gt; [Local1] &lt;--PPP--&gt; [ISP-Serv] &lt;--ether--&gt; [T1-GW]</literallayout>
</textobject>
</mediaobject>
<para>The hosts <hostid>Local1</hostid> and
<hostid>Local2</hostid> are at your site.
<hostid>Local1</hostid> is connected to an ISP via a dial up
PPP connection. This PPP server computer is connected through
a local area network to another gateway computer through an
external interface to the ISPs Internet feed.</para>
<para>The default routes for each of your machines will
be:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="3">
<thead>
<row>
<entry>Host</entry>
<entry>Default Gateway</entry>
<entry>Interface</entry>
</row>
</thead>
<tbody>
<row>
<entry>Local2</entry>
<entry>Local1</entry>
<entry>Ethernet</entry>
</row>
<row>
<entry>Local1</entry>
<entry>T1-GW</entry>
<entry>PPP</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>A common question is <quote>Why (or how) would we set
the <hostid>T1-GW</hostid> to be the default gateway for
<hostid>Local1</hostid>, rather than the ISP server it is
connected to?</quote>.</para>
<para>Remember, since the PPP interface is using an address on
the ISP's local network for your side of the connection,
routes for any other machines on the ISP's local network will
be automatically generated. Hence, you will already know how
to reach the <hostid>T1-GW</hostid> machine, so there is no
need for the intermediate step of sending traffic to the ISP
server.</para>
<para>It is common to use the address
<hostid role="ipaddr">X.X.X.1</hostid> as the gateway address
for your local network. So (using the same example), if your
local class-C address space was
<hostid role="ipaddr">10.20.30</hostid> and your ISP was using
<hostid role="ipaddr">10.9.9</hostid> then the default routes
would be:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>Host</entry>
<entry>Default Route</entry>
</row>
</thead>
<tbody>
<row>
<entry>Local2 (10.20.30.2)</entry>
<entry>Local1 (10.20.30.1)</entry>
</row>
<row>
<entry>Local1 (10.20.30.1, 10.9.9.30)</entry>
<entry>T1-GW (10.9.9.1)</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>You can easily define the default route via the
<filename>/etc/rc.conf</filename> file. In our example, on
the <hostid>Local2</hostid> machine, we added the following
line in <filename>/etc/rc.conf</filename>:</para>
<programlisting>defaultrouter="10.20.30.1"</programlisting>
<para>It is also possible to do it directly from the command
line with the &man.route.8; command:</para>
<screen>&prompt.root; <userinput>route add default 10.20.30.1</userinput></screen>
<para>For more information on manual manipulation of network
routing tables, consult &man.route.8; manual page.</para>
</sect2>
<sect2 id="network-dual-homed-hosts">
<title>Dual Homed Hosts</title>
<indexterm><primary>dual homed hosts</primary></indexterm>
<para>There is one other type of configuration that we should
cover, and that is a host that sits on two different networks.
Technically, any machine functioning as a gateway (in the
example above, using a PPP connection) counts as a dual-homed
host. But the term is really only used to refer to a machine
that sits on two local-area networks.</para>
<para>In one case, the machine has two Ethernet cards, each
having an address on the separate subnets. Alternately, the
machine may only have one Ethernet card, and be using
&man.ifconfig.8; aliasing. The former is used if two
physically separate Ethernet networks are in use, the latter
if there is one physical network segment, but two logically
separate subnets.</para>
<para>Either way, routing tables are set up so that each subnet
knows that this machine is the defined gateway (inbound route)
to the other subnet. This configuration, with the machine
acting as a router between the two subnets, is often used when
we need to implement packet filtering or firewall security in
either or both directions.</para>
<para>If you want this machine to actually forward packets
between the two interfaces, you need to tell FreeBSD to enable
this ability. See the next section for more details on how
to do this.</para>
</sect2>
<sect2 id="network-dedicated-router">
<title>Building a Router</title>
<indexterm><primary>router</primary></indexterm>
<para>A network router is simply a system that forwards packets
from one interface to another. Internet standards and good
engineering practice prevent the FreeBSD Project from enabling
this by default in FreeBSD. You can enable this feature by
changing the following variable to <literal>YES</literal> in
&man.rc.conf.5;:</para>
<programlisting>gateway_enable="YES" # Set to YES if this host will be a gateway</programlisting>
<para>This option will set the &man.sysctl.8; variable
<varname>net.inet.ip.forwarding</varname> to
<literal>1</literal>. If you should need to stop routing
temporarily, you can reset this to <literal>0</literal>
temporarily.</para>
<indexterm><primary>BGP</primary></indexterm>
<indexterm><primary>RIP</primary></indexterm>
<indexterm><primary>OSPF</primary></indexterm>
<para>Your new router will need routes to know where to send the
traffic. If your network is simple enough you can use static
routes. FreeBSD also comes with the standard BSD routing
daemon &man.routed.8;, which speaks RIP (both version 1 and
version 2) and IRDP. Support for BGP v4, OSPF v2, and other
sophisticated routing protocols is available with the
<filename role="package">net/zebra</filename> package.
Commercial products such as <application>&gated;</application>
are also available for more complex network routing
solutions.</para>
</sect2>
<sect2 id="network-static-routes">
<sect2info>
<authorgroup>
<author>
<firstname>Al</firstname>
<surname>Hoang</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect2info>
<!-- Feb 2004 -->
<title>Setting Up Static Routes</title>
<sect3>
<title>Manual Configuration</title>
<para>Let us assume we have a network as follows:</para>
<mediaobject>
<imageobject>
<imagedata fileref="advanced-networking/static-routes">
</imageobject>
<textobject>
<literallayout class="monospaced">
INTERNET
| (10.0.0.1/24) Default Router to Internet
|
|Interface xl0
|10.0.0.10/24
+------+
| | RouterA
| | (FreeBSD gateway)
+------+
| Interface xl1
| 192.168.1.1/24
|
+--------------------------------+
Internal Net 1 | 192.168.1.2/24
|
+------+
| | RouterB
| |
+------+
| 192.168.2.1/24
|
Internal Net 2</literallayout>
</textobject>
</mediaobject>
<para>In this scenario, <hostid>RouterA</hostid> is our &os;
machine that is acting as a router to the rest of the
Internet. It has a default route set to
<hostid role="ipaddr">10.0.0.1</hostid> which allows it to
connect with the outside world. We will assume that
<hostid>RouterB</hostid> is already configured properly and
knows how to get wherever it needs to go. (This is simple
in this picture. Just add a default route on
<hostid>RouterB</hostid> using
<hostid role="ipaddr">192.168.1.1</hostid> as the
gateway.)</para>
<para>If we look at the routing table for
<hostid>RouterA</hostid> we would see something like the
following:</para>
<screen>&prompt.user; <userinput>netstat -nr</userinput>
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif Expire
default 10.0.0.1 UGS 0 49378 xl0
127.0.0.1 127.0.0.1 UH 0 6 lo0
10.0.0.0/24 link#1 UC 0 0 xl0
192.168.1.0/24 link#2 UC 0 0 xl1</screen>
<para>With the current routing table <hostid>RouterA</hostid>
will not be able to reach our Internal Net 2. It does not
have a route for
<hostid role="ipaddr">192.168.2.0/24</hostid>. One way to
alleviate this is to manually add the route. The following
command would add the Internal Net 2 network to
<hostid>RouterA</hostid>'s routing table using
<hostid role="ipaddr">192.168.1.2</hostid> as the next
hop:</para>
<screen>&prompt.root; <userinput>route add -net 192.168.2.0/24 192.168.1.2</userinput></screen>
<para>Now <hostid>RouterA</hostid> can reach any hosts on the
<hostid role="ipaddr">192.168.2.0/24</hostid>
network.</para>
</sect3>
<sect3>
<title>Persistent Configuration</title>
<para>The above example is perfect for configuring a static
route on a running system. However, one problem is that the
routing information will not persist if you reboot your &os;
machine. The way to handle the addition of a static route
is to put it in your <filename>/etc/rc.conf</filename>
file:</para>
<programlisting># Add Internal Net 2 as a static route
static_routes="internalnet2"
route_internalnet2="-net 192.168.2.0/24 192.168.1.2"</programlisting>
<para>The <literal>static_routes</literal> configuration
variable is a list of strings separated by a space. Each
string references to a route name. In our above example we
only have one string in <literal>static_routes</literal>.
This string is <replaceable>internalnet2</replaceable>. We
then add a configuration variable called
<literal>route_<replaceable>internalnet2</replaceable></literal>
where we put all of the configuration parameters we would
give to the &man.route.8; command. For our example above we
would have used the command:</para>
<screen>&prompt.root; <userinput>route add -net 192.168.2.0/24 192.168.1.2</userinput></screen>
<para>so we need <literal>"-net 192.168.2.0/24
192.168.1.2"</literal>.</para>
<para>As said above, we can have more than one string in
<literal>static_routes</literal>. This allows us to create
multiple static routes. The following lines shows an
example of adding static routes for the
<hostid role="ipaddr">192.168.0.0/24</hostid> and
<hostid role="ipaddr">192.168.1.0/24</hostid> networks on an
imaginary router:</para>
<programlisting>static_routes="net1 net2"
route_net1="-net 192.168.0.0/24 192.168.0.1"
route_net2="-net 192.168.1.0/24 192.168.1.1"</programlisting>
</sect3>
</sect2>
<sect2 id="network-routing-propagation">
<title>Routing Propagation</title>
<indexterm><primary>routing propagation</primary></indexterm>
<para>We have already talked about how we define our routes to
the outside world, but not about how the outside world finds
us.</para>
<para>We already know that routing tables can be set up so that
all traffic for a particular address space (in our examples, a
class-C subnet) can be sent to a particular host on that
network, which will forward the packets inbound.</para>
<para>When you get an address space assigned to your site, your
service provider will set up their routing tables so that all
traffic for your subnet will be sent down your PPP link to
your site. But how do sites across the country know to send
to your ISP?</para>
<para>There is a system (much like the distributed DNS
information) that keeps track of all assigned address-spaces,
and defines their point of connection to the Internet
Backbone. The <quote>Backbone</quote> are the main trunk
lines that carry Internet traffic across the country, and
around the world. Each backbone machine has a copy of a
master set of tables, which direct traffic for a particular
network to a specific backbone carrier, and from there down
the chain of service providers until it reaches your
network.</para>
<para>It is the task of your service provider to advertise to
the backbone sites that they are the point of connection (and
thus the path inward) for your site. This is known as route
propagation.</para>
</sect2>
<sect2 id="network-routing-troubleshooting">
<title>Troubleshooting</title>
<indexterm>
<primary><command>traceroute</command></primary>
</indexterm>
<para>Sometimes, there is a problem with routing propagation,
and some sites are unable to connect to you. Perhaps the most
useful command for trying to figure out where routing is
breaking down is the &man.traceroute.8; command. It is
equally useful if you cannot seem to make a connection to a
remote machine (i.e., &man.ping.8; fails).</para>
<para>The &man.traceroute.8; command is run with the name of the
remote host you are trying to connect to. It will show the
gateway hosts along the path of the attempt, eventually either
reaching the target host, or terminating because of a lack of
connection.</para>
<para>For more information, see the manual page for
&man.traceroute.8;.</para>
</sect2>
<sect2 id="network-routing-multicast">
<title>Multicast Routing</title>
<indexterm>
<primary>multicast routing</primary>
</indexterm>
<indexterm>
<primary>kernel options</primary>
<secondary>MROUTING</secondary>
</indexterm>
<para>FreeBSD supports both multicast applications and multicast
routing natively. Multicast applications do not require any
special configuration of FreeBSD; applications will generally
run out of the box. Multicast routing
requires that support be compiled into the kernel:</para>
<programlisting>options MROUTING</programlisting>
<para>In addition, the multicast routing daemon, &man.mrouted.8;
must be configured to set up tunnels and
<acronym>DVMRP</acronym> via
<filename>/etc/mrouted.conf</filename>. More details on
multicast configuration may be found in the manual page for
&man.mrouted.8;.</para>
<note>
<para>The &man.mrouted.8; multicast routing daemon implements
the <acronym>DVMRP</acronym> multicast routing protocol,
which has largely been replaced by &man.pim.4; in many
multicast installations. &man.mrouted.8; and the related
&man.map-mbone.8; and &man.mrinfo.8; utilities are available
in the &os; Ports&nbsp;Collection as
<filename role="package">net/mrouted</filename>.</para>
</note>
</sect2>
</sect1>
<sect1 id="network-wireless">
<sect1info>
<authorgroup>
<author>
<othername>Loader</othername>
</author>
<author>
<firstname>Marc</firstname>
<surname>Fonvieille</surname>
</author>
<author>
<firstname>Murray</firstname>
<surname>Stokely</surname>
</author>
</authorgroup>
</sect1info>
<title>Wireless Networking</title>
<indexterm><primary>wireless networking</primary></indexterm>
<indexterm>
<primary>802.11</primary>
<see>wireless networking</see>
</indexterm>
<sect2>
<title>Wireless Networking Basics</title>
<para>Most wireless networks are based on the &ieee; 802.11
standards. A basic wireless network consists of multiple
stations communicating with radios that broadcast in either
the 2.4GHz or 5GHz band (though this varies according to the
locale and is also changing to enable communication in the
2.3GHz and 4.9GHz ranges).</para>
<para>802.11 networks are organized in two ways: in
<emphasis>infrastructure mode</emphasis> one station acts as a
master with all the other stations associating to it; the
network is known as a BSS and the master station is termed an
access point (AP). In a BSS all communication passes through
the AP; even when one station wants to communicate with
another wireless station messages must go through the AP. In
the second form of network there is no master and stations
communicate directly. This form of network is termed an IBSS
and is commonly known as an
<emphasis>ad-hoc network</emphasis>.</para>
<para>802.11 networks were first deployed in the 2.4GHz band
using protocols defined by the &ieee; 802.11 and 802.11b
standard. These specifications include the operating
frequencies, MAC layer characteristics including framing and
transmission rates (communication can be done at various
rates). Later the 802.11a standard defined operation in the
5GHz band, including different signalling mechanisms and
higher transmission rates. Still later the 802.11g standard
was defined to enable use of 802.11a signalling and
transmission mechanisms in the 2.4GHz band in such a way as to
be backwards compatible with 802.11b networks.</para>
<para>Separate from the underlying transmission techniques
802.11 networks have a variety of security mechanisms. The
original 802.11 specifications defined a simple security
protocol called WEP. This protocol uses a fixed pre-shared key
and the RC4 cryptographic cipher to encode data transmitted on
a network. Stations must all agree on the fixed key in order
to communicate. This scheme was shown to be easily broken and
is now rarely used except to discourage transient users from
joining networks. Current security practice is given by the
&ieee; 802.11i specification that defines new cryptographic
ciphers and an additional protocol to authenticate stations to
an access point and exchange keys for doing data
communication. Further, cryptographic keys are periodically
refreshed and there are mechanisms for detecting intrusion
attempts (and for countering intrusion attempts). Another
security protocol specification commonly used in wireless
networks is termed WPA. This was a precursor to 802.11i
defined by an industry group as an interim measure while
waiting for 802.11i to be ratified. WPA specifies a subset of
the requirements found in 802.11i and is designed for
implementation on legacy hardware. Specifically WPA requires
only the TKIP cipher that is derived from the original WEP
cipher. 802.11i permits use of TKIP but also requires support
for a stronger cipher, AES-CCM, for encrypting data. (The AES
cipher was not required in WPA because it was deemed too
computationally costly to be implemented on legacy
hardware.)</para>
<para>Other than the above protocol standards the other
important standard to be aware of is 802.11e. This defines
protocols for deploying multi-media applications such as
streaming video and voice over IP (VoIP) in an 802.11 network.
Like 802.11i, 802.11e also has a precursor specification
termed WME (later renamed WMM) that has been defined by an
industry group as a subset of 802.11e that can be deployed now
to enable multi-media applications while waiting for the final
ratification of 802.11e. The most important thing to know
about 802.11e and WME/WMM is that it enables prioritized
traffic use of a wireless network through Quality of Service
(QoS) protocols and enhanced media access protocols. Proper
implementation of these protocols enable high speed bursting
of data and prioritized traffic flow.</para>
<para>&os; supports networks that operate
using 802.11a, 802.11b, and 802.11g. The WPA and 802.11i
security protocols are likewise supported (in conjunction with
any of 11a, 11b, and 11g) and QoS and traffic prioritization
required by the WME/WMM protocols are supported for a limited
set of wireless devices.</para>
</sect2>
<sect2 id="network-wireless-basic">
<title>Basic Setup</title>
<sect3>
<title>Kernel Configuration</title>
<para>To use wireless networking, you need a wireless
networking card and to configure the kernel with the
appropriate wireless networking support. The latter is
separated into multiple modules so that you only need to
configure the software you are actually going to use.</para>
<para>The first thing you need is a wireless device. The most
commonly used devices are those that use parts made by
Atheros. These devices are supported by the &man.ath.4;
driver and require the following line to be added to the
<filename>/boot/loader.conf</filename> file:</para>
<programlisting>if_ath_load="YES"</programlisting>
<para>The Atheros driver is split up into three separate
pieces: the proper driver (&man.ath.4;), the hardware
support layer that handles chip-specific functions
(&man.ath.hal.4;), and an algorithm for selecting which of
several possible rates for transmitting frames
(ath_rate_sample here). When this support is loaded as
kernel modules, these dependencies are automatically handled
for you. If, instead of an Atheros device, you had another
device you would select the module for that device;
e.g.:</para>
<programlisting>if_wi_load="YES"</programlisting>
<para>for devices based on the Intersil Prism parts
(&man.wi.4; driver).</para>
<note>
<para>In the rest of this document, we will use an
&man.ath.4; device, the device name in the examples must
be changed according to your configuration. A list of
available wireless drivers and supported adapters can be
found in the &os; Hardware Notes. Copies of these notes
for various releases and architectures are available on
the <ulink
url="http://www.FreeBSD.org/releases/index.html">Release
Information</ulink> page of the &os; Web site. If a
native &os; driver for your wireless device does not
exist, it may be possible to directly use the &windows;
driver with the help of the
<link linkend="config-network-ndis">NDIS</link> driver
wrapper.</para>
</note>
<para>Under &os;&nbsp;7.X, with a device driver you need to
also bring in the 802.11 networking support required by the
driver. For the &man.ath.4; driver these are at least the
&man.wlan.4;, <literal>wlan_scan_ap</literal> and
<literal>wlan_scan_sta</literal> modules; the &man.wlan.4;
module is automatically loaded with the wireless device
driver, the remaining modules must be loaded at boot time
via the <filename>/boot/loader.conf</filename> file:</para>
<programlisting>wlan_scan_ap_load="YES"
wlan_scan_sta_load="YES"</programlisting>
<para>Since &os;&nbsp;8.0, these modules are part of the
base &man.wlan.4; driver which is dynamically loaded with
the adapter driver.</para>
<para>With that, you will need the modules that implement
cryptographic support for the security protocols you intend
to use. These are intended to be dynamically loaded on
demand by the &man.wlan.4; module but for now they must be
manually configured. The following modules are available:
&man.wlan.wep.4;, &man.wlan.ccmp.4; and &man.wlan.tkip.4;.
Both &man.wlan.ccmp.4; and &man.wlan.tkip.4; drivers are
only needed if you intend to use the WPA and/or 802.11i
security protocols. If your network does not use
encryption, you will not need &man.wlan.wep.4; support. To
load these modules at boot time, add the following lines to
<filename>/boot/loader.conf</filename>:</para>
<programlisting>wlan_wep_load="YES"
wlan_ccmp_load="YES"
wlan_tkip_load="YES"</programlisting>
<para>With this information in the system bootstrap
configuration file (i.e.,
<filename>/boot/loader.conf</filename>), you have to reboot
your &os; box. If you do not want to reboot your machine
for the moment, you can load the modules by hand using
&man.kldload.8;.</para>
<note>
<para>If you do not want to use modules, it is possible to
compile these drivers into the kernel by adding the
following lines to your kernel configuration file:</para>
<programlisting>device wlan # 802.11 support
device wlan_wep # 802.11 WEP support
device wlan_ccmp # 802.11 CCMP support
device wlan_tkip # 802.11 TKIP support
device wlan_amrr # AMRR transmit rate control algorithm
device ath # Atheros pci/cardbus NIC's
device ath_hal # pci/cardbus chip support
options AH_SUPPORT_AR5416 # enable AR5416 tx/rx descriptors
device ath_rate_sample # SampleRate tx rate control for ath</programlisting>
<para>Both following lines are also required by
&os;&nbsp;7.X, other &os; versions do not need
them:</para>
<programlisting>device wlan_scan_ap # 802.11 AP mode scanning
device wlan_scan_sta # 802.11 STA mode scanning</programlisting>
<para>With this information in the kernel configuration
file, recompile the kernel and reboot your &os;
machine.</para>
</note>
<para>When the system is up, we could find some information
about the wireless device in the boot messages, like
this:</para>
<screen>ath0: &lt;Atheros 5212&gt; mem 0x88000000-0x8800ffff irq 11 at device 0.0 on cardbus1
ath0: [ITHREAD]
ath0: AR2413 mac 7.9 RF2413 phy 4.5</screen>
</sect3>
</sect2>
<sect2>
<title>Infrastructure Mode</title>
<para>The infrastructure mode or BSS mode is the mode that is
typically used. In this mode, a number of wireless access
points are connected to a wired network. Each wireless
network has its own name, this name is called the SSID of the
network. Wireless clients connect to the wireless access
points.</para>
<sect3>
<title>&os; Clients</title>
<sect4>
<title>How to Find Access Points</title>
<para>To scan for networks, use the
<command>ifconfig</command> command. This request may
take a few moments to complete as it requires that the
system switches to each available wireless frequency and
probes for available access points. Only the super-user
can initiate such a scan:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> up scan</userinput>
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS
dlinkap 00:13:46:49:41:76 11 54M -90:96 100 EPS WPA WME
freebsdap 00:11:95:c3:0d:ac 1 54M -83:96 100 EPS WPA</screen>
<note>
<para>You must mark the interface <option>up</option>
before you can scan. Subsequent scan requests do not
require you to mark the interface up again.</para>
</note>
<note>
<para>Under &os;&nbsp;7.X, the adapter device, for example
<devicename><replaceable>ath0</replaceable></devicename>,
is used directly instead of the
<devicename>wlan<replaceable>0</replaceable></devicename>
device. This requires you to replace the both previous
lines with:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> up scan</userinput></screen>
<para>In the rest of this document, &os;&nbsp;7.X users
will need to change the command and configuration lines
according to that scheme.</para>
</note>
<para>The output of a scan request lists each BSS/IBSS
network found. Beside the name of the network,
<literal>SSID</literal>, we find the
<literal>BSSID</literal> which is the MAC address of the
access point. The <literal>CAPS</literal> field
identifies the type of each network and the capabilities
of the stations operating there:</para>
<table frame="none" pgwide="0">
<title>Station Capability Codes</title>
<tgroup cols="2">
<thead>
<row>
<entry>Capability Code</entry>
<entry>Meaning</entry>
</row>
</thead>
<tbody>
<row>
<entry><literal>E</literal></entry>
<entry>Extended Service Set (ESS). Indicates that
the station is part of an infrastructure network
(in contrast to an IBSS/ad-hoc network).</entry>
</row>
<row>
<entry><literal>I</literal></entry>
<entry>IBSS/ad-hoc network. Indicates that the
station is part of an ad-hoc network (in contrast
to an ESS network).</entry>
</row>
<row>
<entry><literal>P</literal></entry>
<entry>Privacy. Data confidentiality is required
for all data frames exchanged within the BSS.
This means that this BSS requires the station to
use cryptographic means such as WEP, TKIP or
AES-CCMP to encrypt/decrypt data frames being
exchanged with others.</entry>
</row>
<row>
<entry><literal>S</literal></entry>
<entry>Short Preamble. Indicates that the network
is using short preambles (defined in 802.11b High
Rate/DSSS PHY, short preamble utilizes a 56 bit
sync field in contrast to a 128 bit field used in
long preamble mode).</entry>
</row>
<row>
<entry><literal>s</literal></entry>
<entry>Short slot time. Indicates that the 802.11g
network is using a short slot time because there
are no legacy (802.11b) stations present.</entry>
</row>
</tbody>
</tgroup>
</table>
<para>One can also display the current list of known
networks with:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> list scan</userinput></screen>
<para>This information may be updated automatically by the
adapter or manually with a <option>scan</option> request.
Old data is automatically removed from the cache, so over
time this list may shrink unless more scans are
done.</para>
</sect4>
<sect4>
<title>Basic Settings</title>
<para>This section provides a simple example of how to make
the wireless network adapter work in &os; without
encryption. After you are familiar with these concepts,
we strongly recommend using
<link linkend="network-wireless-wpa">WPA</link> to set up
your wireless network.</para>
<para>There are three basic steps to configure a wireless
network: selecting an access point, authenticating your
station, and configuring an IP address. The following
sections discuss each step.</para>
<sect5>
<title>Selecting an Access Point</title>
<para>Most of time it is sufficient to let the system
choose an access point using the builtin heuristics.
This is the default behaviour when you mark an interface
up or otherwise configure an interface by listing it in
<filename>/etc/rc.conf</filename>, e.g.:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="DHCP"</programlisting>
<note>
<para>As previously mentioned, &os;&nbsp;7.X will only
require a line related to the adapter device:</para>
<programlisting>ifconfig_ath0="DHCP"</programlisting>
</note>
<para>If there are multiple access points and you want to
select a specific one, you can select it by its
SSID:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="ssid <replaceable>your_ssid_here</replaceable> DHCP"</programlisting>
<para>In an environment where there are multiple access
points with the same SSID (often done to simplify
roaming) it may be necessary to associate to one
specific device. In this case you can also specify the
BSSID of the access point (you can also leave off the
SSID):</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="ssid <replaceable>your_ssid_here</replaceable> bssid <replaceable>xx:xx:xx:xx:xx:xx</replaceable> DHCP"</programlisting>
<para>There are other ways to constrain the choice of an
access point such as limiting the set of frequencies the
system will scan on. This may be useful if you have a
multi-band wireless card as scanning all the possible
channels can be time-consuming. To limit operation to a
specific band you can use the <option>mode</option>
parameter; e.g.:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="mode <replaceable>11g</replaceable> ssid <replaceable>your_ssid_here</replaceable> DHCP"</programlisting>
<para>will force the card to operate in 802.11g which is
defined only for 2.4GHz frequencies so any 5GHz channels
will not be considered. Other ways to do this are the
<option>channel</option> parameter, to lock operation to
one specific frequency, and the
<option>chanlist</option> parameter, to specify a list
of channels for scanning. More information about these
parameters can be found in the &man.ifconfig.8; manual
page.</para>
</sect5>
<sect5>
<title>Authentication</title>
<para>Once you have selected an access point your station
needs to authenticate before it can pass data.
Authentication can happen in several ways. The most
common scheme used is termed open authentication and
allows any station to join the network and communicate.
This is the authentication you should use for test
purpose the first time you set up a wireless network.
Other schemes require cryptographic handshakes be
completed before data traffic can flow; either using
pre-shared keys or secrets, or more complex schemes that
involve backend services such as RADIUS. Most users
will use open authentication which is the default
setting. Next most common setup is WPA-PSK, also known
as WPA Personal, which is described <link
linkend="network-wireless-wpa-wpa-psk">below</link>.</para>
<note>
<para>If you have an &apple; &airport; Extreme base
station for an access point you may need to configure
shared-key authentication together with a WEP key.
This can be done in the
<filename>/etc/rc.conf</filename> file or using the
&man.wpa.supplicant.8; program. If you have a single
&airport; base station you can setup access with
something like:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="authmode shared wepmode on weptxkey <replaceable>1</replaceable> wepkey <replaceable>01234567</replaceable> DHCP"</programlisting>
<para>In general shared key authentication is to be
avoided because it uses the WEP key material in a
highly-constrained manner making it even easier to
crack the key. If WEP must be used (e.g., for
compatibility with legacy devices) it is better to use
WEP with <literal>open</literal> authentication. More
information regarding WEP can be found in the
<xref linkend="network-wireless-wep">.</para>
</note>
</sect5>
<sect5>
<title>Getting an IP Address with DHCP</title>
<para>Once you have selected an access point and set the
authentication parameters, you will have to get an IP
address to communicate. Most of time you will obtain
your wireless IP address via DHCP. To achieve that,
edit <filename>/etc/rc.conf</filename> and add
<literal>DHCP</literal> to the configuration for your
device as shown in various examples above:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="DHCP"</programlisting>
<para>At this point, you are ready to bring up the
wireless interface:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/netif start</userinput></screen>
<para>Once the interface is running, use
<command>ifconfig</command> to see the status of the
interface <devicename>ath0</devicename>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.1.100 netmask 0xffffff00 broadcast 192.168.1.255
media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
status: associated
ssid dlinkap channel 11 (2462 Mhz 11g) bssid 00:13:46:49:41:76
country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7
scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7
roam:rate 5 protmode CTS wme burst</screen>
<para>The <literal>status: associated</literal> means you
are connected to the wireless network (to the
<literal>dlinkap</literal> network in our case). The
<literal>bssid 00:13:46:49:41:76</literal> part is the
MAC address of your access point; the
<literal>authmode OPEN</literal> part informs you that
the communication is not encrypted.</para>
</sect5>
<sect5>
<title>Static IP Address</title>
<para>In the case you cannot obtain an IP address from a
DHCP server, you can set a fixed IP address. Replace
the <literal>DHCP</literal> keyword shown above with the
address information. Be sure to retain any other
parameters you have set up for selecting an access
point:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="inet <replaceable>192.168.1.100</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>your_ssid_here</replaceable>"</programlisting>
</sect5>
</sect4>
<sect4 id="network-wireless-wpa">
<title>WPA</title>
<para>WPA (Wi-Fi Protected Access) is a security protocol
used together with 802.11 networks to address the lack of
proper authentication and the weakness of
<link linkend="network-wireless-wep">WEP</link>. WPA
leverages the 802.1X authentication protocol and uses one
of several ciphers instead of WEP for data integrity. The
only cipher required by WPA is TKIP (Temporary Key
Integrity Protocol). TKIP is a cipher that extends the
basic RC4 cipher used by WEP by adding integrity checking,
tamper detection, and measures for responding to any
detected intrusions. TKIP is designed to work on legacy
hardware with only software modification; it represents a
compromise that improves security but is still not
entirely immune to attack. WPA also specifies the
AES-CCMP cipher as an alternative to TKIP and that is
preferred when possible; for this specification the term
WPA2 (or RSN) is commonly used.</para>
<para>WPA defines authentication and encryption protocols.
Authentication is most commonly done using one of two
techniques: by 802.1X and a backend authentication service
such as RADIUS, or by a minimal handshake between the
station and the access point using a pre-shared secret.
The former is commonly termed WPA Enterprise with the
latter known as WPA Personal. Since most people will not
set up a RADIUS backend server for their wireless network,
WPA-PSK is by far the most commonly encountered
configuration for WPA.</para>
<para>The control of the wireless connection and the
authentication (key negotiation or authentication with a
server) is done with the &man.wpa.supplicant.8; utility.
This program requires a configuration file,
<filename>/etc/wpa_supplicant.conf</filename>, to run.
More information regarding this file can be found in the
&man.wpa.supplicant.conf.5; manual page.</para>
<sect5 id="network-wireless-wpa-wpa-psk">
<title>WPA-PSK</title>
<para>WPA-PSK, also known as WPA-Personal, is based on a
pre-shared key (PSK) generated from a given password and
that will be used as the master key in the wireless
network. This means every wireless user will share the
same key. WPA-PSK is intended for small networks where
the use of an authentication server is not possible or
desired.</para>
<warning>
<para>Always use strong passwords that are
sufficiently long and made from a rich alphabet so
they will not be guessed and/or attacked.</para>
</warning>
<para>The first step is the configuration of the
<filename>/etc/wpa_supplicant.conf</filename> file with
the SSID and the pre-shared key of your network:</para>
<programlisting>network={
ssid="freebsdap"
psk="freebsdmall"
}</programlisting>
<para>Then, in <filename>/etc/rc.conf</filename>, we
indicate that the wireless device configuration will be
done with WPA and the IP address will be obtained with
DHCP:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="WPA DHCP"</programlisting>
<para>Then we can bring up the interface:</para>
<screen>&prompt.root; <userinput><filename>/etc/rc.d/netif</filename> start</userinput>
Starting wpa_supplicant.
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 6
DHCPOFFER from 192.168.0.1
DHCPREQUEST on wlan0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.1
bound to 192.168.0.254 -- renewal in 300 seconds.
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
<para>Or you can try to configure it manually using the
same <filename>/etc/wpa_supplicant.conf</filename> <link
linkend="network-wireless-wpa-wpa-psk">above</link>, and
run:</para>
<screen>&prompt.root; <userinput>wpa_supplicant -i <replaceable>wlan0</replaceable> -c /etc/wpa_supplicant.conf</userinput>
Trying to associate with 00:11:95:c3:0d:ac (SSID='freebsdap' freq=2412 MHz)
Associated with 00:11:95:c3:0d:ac
WPA: Key negotiation completed with 00:11:95:c3:0d:ac [PTK=CCMP GTK=CCMP]
CTRL-EVENT-CONNECTED - Connection to 00:11:95:c3:0d:ac completed (auth) [id=0 id_str=]</screen>
<para>The next operation is the launch of the
<command>dhclient</command> command to get the IP
address from the DHCP server:</para>
<screen>&prompt.root; <userinput>dhclient <replaceable>wlan0</replaceable></userinput>
DHCPREQUEST on wlan0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.1
bound to 192.168.0.254 -- renewal in 300 seconds.
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
<note>
<para>If <filename>/etc/rc.conf</filename> has an
<literal>ifconfig_wlan0</literal> entry with the
<literal>DHCP</literal> string (like
<literal>ifconfig_wlan0="DHCP"</literal>),
<command>dhclient</command> will be launched
automatically after <command>wpa_supplicant</command>
associates with the access point.</para>
</note>
<para>If DHCP is not possible or desired,
you can set a static IP address after
<command>wpa_supplicant</command> has authenticated the
station:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.100</replaceable> netmask <replaceable>255.255.255.0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.100 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
<para>When DHCP is not used, you also have to manually set
the default gateway and the nameserver:</para>
<screen>&prompt.root; <userinput>route add default <replaceable>your_default_router</replaceable></userinput>
&prompt.root; <userinput>echo "nameserver <replaceable>your_DNS_server</replaceable>" &gt;&gt; /etc/resolv.conf</userinput></screen>
</sect5>
<sect5 id="network-wireless-wpa-eap-tls">
<title>WPA with EAP-TLS</title>
<para>The second way to use WPA is with an 802.1X backend
authentication server. In this case WPA is called
WPA-Enterprise to differentiate it from the less secure
WPA-Personal with its pre-shared key.
Authentication in WPA-Enterprise is based on the
Extensible Authentication Protocol (EAP).</para>
<para>EAP does not come with an encryption method.
Instead, it was decided to embed EAP inside an encrypted
tunnel. There are many EAP authentication methods, but
EAP-TLS, EAP-TTLS, and EAP-PEAP are the most
common.</para>
<para>EAP-TLS (EAP with Transport Layer Security) is a
very well-supported authentication protocol in the
wireless world since it was the first EAP method to be
certified by the <ulink
url="http://www.wi-fi.org/">Wi-Fi alliance</ulink>.
EAP-TLS will require three certificates to run: the CA
certificate (installed on all machines), the server
certificate for your authentication server, and one
client certificate for each wireless client. In this
EAP method, both authentication server and wireless
client authenticate each other in presenting their
respective certificates, and they verify that these
certificates were signed by your organization's
certificate authority (CA).</para>
<para>As previously, the configuration is done via
<filename>/etc/wpa_supplicant.conf</filename>:</para>
<programlisting>network={
ssid="freebsdap" <co id="co-tls-ssid">
proto=RSN <co id="co-tls-proto">
key_mgmt=WPA-EAP <co id="co-tls-kmgmt">
eap=TLS <co id="co-tls-eap">
identity="loader" <co id="co-tls-id">
ca_cert="/etc/certs/cacert.pem" <co id="co-tls-cacert">
client_cert="/etc/certs/clientcert.pem" <co id="co-tls-clientcert">
private_key="/etc/certs/clientkey.pem" <co id="co-tls-pkey">
private_key_passwd="freebsdmallclient" <co id="co-tls-pwd">
}</programlisting>
<calloutlist>
<callout arearefs="co-tls-ssid">
<para>This field indicates the network name
(SSID).</para>
</callout>
<callout arearefs="co-tls-proto">
<para>Here, we use RSN (&ieee; 802.11i) protocol,
i.e., WPA2.</para>
</callout>
<callout arearefs="co-tls-kmgmt">
<para>The <literal>key_mgmt</literal> line refers to
the key management protocol we use. In our case it
is WPA using EAP authentication:
<literal>WPA-EAP</literal>.</para>
</callout>
<callout arearefs="co-tls-eap">
<para>In this field, we mention the EAP method for our
connection.</para>
</callout>
<callout arearefs="co-tls-id">
<para>The <literal>identity</literal> field contains
the identity string for EAP.</para>
</callout>
<callout arearefs="co-tls-cacert">
<para>The <literal>ca_cert</literal> field indicates
the pathname of the CA certificate file. This file
is needed to verify the server certificate.</para>
</callout>
<callout arearefs="co-tls-clientcert">
<para>The <literal>client_cert</literal> line gives
the pathname to the client certificate file. This
certificate is unique to each wireless client of the
network.</para>
</callout>
<callout arearefs="co-tls-pkey">
<para>The <literal>private_key</literal> field is the
pathname to the client certificate private key
file.</para>
</callout>
<callout arearefs="co-tls-pwd">
<para>The <literal>private_key_passwd</literal> field
contains the passphrase for the private key.</para>
</callout>
</calloutlist>
<para>Then add the following lines to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="WPA DHCP"</programlisting>
<para>The next step is to bring up the interface with the
help of the <filename>rc.d</filename> facility:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/netif start</userinput>
Starting wpa_supplicant.
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
<para>As previously shown, it is also possible to bring up
the interface manually with both
<command>wpa_supplicant</command> and
<command>ifconfig</command> commands.</para>
</sect5>
<sect5 id="network-wireless-wpa-eap-ttls">
<title>WPA with EAP-TTLS</title>
<para>With EAP-TLS both the authentication server and the
client need a certificate, with EAP-TTLS (EAP-Tunneled
Transport Layer Security) a client certificate is
optional. This method is close to what some secure web
sites do , where the web server can create a secure SSL
tunnel even if the visitors do not have client-side
certificates. EAP-TTLS will use the encrypted TLS
tunnel for safe transport of the authentication
data.</para>
<para>The configuration is done via the
<filename>/etc/wpa_supplicant.conf</filename>
file:</para>
<programlisting>network={
ssid="freebsdap"
proto=RSN
key_mgmt=WPA-EAP
eap=TTLS <co id="co-ttls-eap">
identity="test" <co id="co-ttls-id">
password="test" <co id="co-ttls-passwd">
ca_cert="/etc/certs/cacert.pem" <co id="co-ttls-cacert">
phase2="auth=MD5" <co id="co-ttls-pha2">
}</programlisting>
<calloutlist>
<callout arearefs="co-ttls-eap">
<para>In this field, we mention the EAP method for our
connection.</para>
</callout>
<callout arearefs="co-ttls-id">
<para>The <literal>identity</literal> field contains
the identity string for EAP authentication inside
the encrypted TLS tunnel.</para>
</callout>
<callout arearefs="co-ttls-passwd">
<para>The <literal>password</literal> field contains
the passphrase for the EAP authentication.</para>
</callout>
<callout arearefs="co-ttls-cacert">
<para>The <literal>ca_cert</literal> field indicates
the pathname of the CA certificate file. This file
is needed to verify the server certificate.</para>
</callout>
<callout arearefs="co-ttls-pha2">
<para>In this field, we mention the authentication
method used in the encrypted TLS tunnel. In our
case, EAP with MD5-Challenge has been used. The
<quote>inner authentication</quote> phase is often
called <quote>phase2</quote>.</para>
</callout>
</calloutlist>
<para>You also have to add the following lines to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="WPA DHCP"</programlisting>
<para>The next step is to bring up the interface:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/netif start</userinput>
Starting wpa_supplicant.
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
</sect5>
<sect5 id="network-wireless-wpa-eap-peap">
<title>WPA with EAP-PEAP</title>
<note>
<para>PEAPv0/EAP-MSCHAPv2 is the most common PEAP
method. In the rest of this document, we will use the
PEAP term to refer to that method.</para>
</note>
<para>PEAP (Protected EAP) has been designed as an
alternative to EAP-TTLS, and is the most used EAP
standard after EAP-TLS. In other words, if you have a
network with mixed OSes, PEAP should be the most
supported standard after EAP-TLS.</para>
<para>PEAP is similar to EAP-TTLS: it uses a server-side
certificate to authenticate clients by creating an
encrypted TLS tunnel between the client and the
authentication server, which protects the ensuing
exchange of authentication information. In terms of
security, the difference between EAP-TTLS and PEAP is
that PEAP authentication broadcasts the username in the
clear, with only the password sent in the encrypted TLS
tunnel. EAP-TTLS will use the TLS tunnel for both
username and password.</para>
<para>We have to edit the
<filename>/etc/wpa_supplicant.conf</filename> file and
add the EAP-PEAP related settings:</para>
<programlisting>network={
ssid="freebsdap"
proto=RSN
key_mgmt=WPA-EAP
eap=PEAP <co id="co-peap-eap">
identity="test" <co id="co-peap-id">
password="test" <co id="co-peap-passwd">
ca_cert="/etc/certs/cacert.pem" <co id="co-peap-cacert">
phase1="peaplabel=0" <co id="co-peap-pha1">
phase2="auth=MSCHAPV2" <co id="co-peap-pha2">
}</programlisting>
<calloutlist>
<callout arearefs="co-peap-eap">
<para>In this field, we mention the EAP method for our
connection.</para>
</callout>
<callout arearefs="co-peap-id">
<para>The <literal>identity</literal> field contains
the identity string for EAP authentication inside
the encrypted TLS tunnel.</para>
</callout>
<callout arearefs="co-peap-passwd">
<para>The <literal>password</literal> field contains
the passphrase for the EAP authentication.</para>
</callout>
<callout arearefs="co-peap-cacert">
<para>The <literal>ca_cert</literal> field indicates
the pathname of the CA certificate file. This file
is needed to verify the server certificate.</para>
</callout>
<callout arearefs="co-peap-pha1">
<para>This field contains the parameters for the
first phase of authentication (the TLS tunnel).
According to the authentication server used, you
will have to specify a specific label for
authentication. Most of the time, the label will be
<quote>client EAP encryption</quote> which is set by
using <literal>peaplabel=0</literal>. More
information can be found in the
&man.wpa.supplicant.conf.5; manual page.</para>
</callout>
<callout arearefs="co-peap-pha2">
<para>In this field, we mention the authentication
protocol used in the encrypted TLS tunnel. In the
case of PEAP, it is
<literal>auth=MSCHAPV2</literal>.</para>
</callout>
</calloutlist>
<para>The following must be added to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>wlans_ath0="wlan0"
ifconfig_wlan0="WPA DHCP"</programlisting>
<para>Then we can bring up the interface:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/netif start</userinput>
Starting wpa_supplicant.
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF
AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan
bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS
wme burst roaming MANUAL</screen>
</sect5>
</sect4>
<sect4 id="network-wireless-wep">
<title>WEP</title>
<para>WEP (Wired Equivalent Privacy) is part of the original
802.11 standard. There is no authentication mechanism,
only a weak form of access control, and it is easily
cracked.</para>
<para>WEP can be set up with
<command>ifconfig</command>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.1.100</replaceable> netmask <replaceable>255.255.255.0</replaceable> \
ssid <replaceable>my_net</replaceable> wepmode on weptxkey <replaceable>3</replaceable> wepkey <replaceable>3:0x3456789012</replaceable></userinput></screen>
<itemizedlist>
<listitem>
<para>The <literal>weptxkey</literal> means which WEP
key will be used in the transmission. Here we used
the third key. This must match the setting in the
access point. If you do not have any idea of which
key is used by the access point, try
<literal>1</literal> (i.e., the first key) for this
value.</para>
</listitem>
<listitem>
<para>The <literal>wepkey</literal> selects one of the
WEP keys. It should be in the format
<replaceable>index:key</replaceable>. Key
<literal>1</literal> is used by default; the index
only needs to be set if we use a key other
than the first key.</para>
<note>
<para>You must replace the
<literal>0x3456789012</literal> with the key
configured for use on the access point.</para>
</note>
</listitem>
</itemizedlist>
<para>You are encouraged to read the &man.ifconfig.8; manual
page for further information.</para>
<para>The <command>wpa_supplicant</command> facility also
can be used to configure your wireless interface with WEP.
The example above can be set up by adding the following
lines to
<filename>/etc/wpa_supplicant.conf</filename>:</para>
<programlisting>network={
ssid="my_net"
key_mgmt=NONE
wep_key3=3456789012
wep_tx_keyidx=3
}</programlisting>
<para>Then:</para>
<screen>&prompt.root; <userinput>wpa_supplicant -i <replaceable>wlan0</replaceable> -c /etc/wpa_supplicant.conf</userinput>
Trying to associate with 00:13:46:49:41:76 (SSID='dlinkap' freq=2437 MHz)
Associated with 00:13:46:49:41:76</screen>
</sect4>
</sect3>
</sect2>
<sect2>
<title>Ad-hoc Mode</title>
<para>IBSS mode, also called ad-hoc mode, is designed for point
to point connections. For example, to establish an ad-hoc
network between the machine <hostid>A</hostid> and the machine
<hostid>B</hostid>, we will just need to choose two IP
addresses and a SSID.</para>
<para>On the box <hostid>A</hostid>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable> wlanmode adhoc</userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 00:11:95:c3:0d:ac
inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet autoselect mode 11g &lt;adhoc&gt;
status: running
ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac
country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
protmode CTS wme burst</screen>
<para>The <literal>adhoc</literal> parameter indicates the
interface is running in the IBSS mode.</para>
<para>On <hostid>B</hostid>, we should be able to detect
<hostid>A</hostid>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable> wlanmode adhoc</userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> up scan</userinput>
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS
freebsdap 02:11:95:c3:0d:ac 2 54M -64:-96 100 IS WME</screen>
<para>The <literal>I</literal> in the output confirms the
machine <hostid>A</hostid> is in ad-hoc mode. We just have to
configure <hostid>B</hostid> with a different IP
address:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.2</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet autoselect mode 11g &lt;adhoc&gt;
status: running
ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac
country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
protmode CTS wme burst</screen>
<para>Both <hostid>A</hostid> and <hostid>B</hostid> are now
ready to exchange information.</para>
</sect2>
<sect2 id="network-wireless-ap">
<title>&os; Host Access Points</title>
<para>&os; can act as an Access Point (AP) which eliminates the
need to buy a hardware AP or run an ad-hoc network. This can
be particularly useful when your &os; machine is acting as a
gateway to another network (e.g., the Internet).</para>
<sect3 id="network-wireless-ap-basic">
<title>Basic Settings</title>
<para>Before configuring your &os; machine as an AP, the
kernel must be configured with the appropriate wireless
networking support for your wireless card. You also have to
add support for the security protocols you intend to
use. For more details, see
<xref linkend="network-wireless-basic">.</para>
<note>
<para>The use of the NDIS driver wrapper and the &windows;
drivers do not currently allow AP operation. Only native
&os; wireless drivers support AP mode.</para>
</note>
<para>Once wireless networking support is loaded, you can
check if your wireless device supports the host-based access
point mode (also known as hostap mode):</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> list caps</userinput>
drivercaps=6f85edc1&lt;STA,FF,TURBOP,IBSS,HOSTAP,AHDEMO,TXPMGT,SHSLOT,SHPREAMBLE,MONITOR,MBSS,WPA1,WPA2,BURST,WME,WDS,BGSCAN,TXFRAG&gt;
cryptocaps=1f&lt;WEP,TKIP,AES,AES_CCM,TKIPMIC&gt;</screen>
<para>This output displays the card capabilities; the
<literal>HOSTAP</literal> word confirms this wireless card
can act as an Access Point. Various supported ciphers are
also mentioned: WEP, TKIP, AES, etc. This information
is important to know what security protocols can be used
on the Access Point.</para>
<para>The wireless device can only be put into hostap mode
during the creation of the network pseudo-device, so a
previously created device must be destroyed first:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> destroy</userinput></screen>
<para>then regenerated with the correct option before setting
the other parameters:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable> wlanmode hostap</userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable> mode 11g channel 1</userinput></screen>
<para>Use <command>ifconfig</command> again to see the status
of the <devicename>wlan0</devicename> interface:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 00:11:95:c3:0d:ac
inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet autoselect mode 11g &lt;hostap&gt;
status: running
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60
protmode CTS wme burst dtimperiod 1 -dfs</screen>
<para>The <literal>hostap</literal> parameter indicates the
interface is running in the host-based access point
mode.</para>
<para>The interface configuration can be done automatically at
boot time by adding the following lines to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>wlans_ath0="wlan0"
create_args_wlan0="wlanmode hostap"
ifconfig_wlan0="inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable> mode 11g channel <replaceable>1</replaceable>"</programlisting>
</sect3>
<sect3>
<title>Host-based Access Point Without Authentication or
Encryption</title>
<para>Although it is not recommended to run an AP without any
authentication or encryption, this is a simple way to check
if your AP is working. This configuration is also important
for debugging client issues.</para>
<para>Once the AP configured as previously shown, it is
possible from another wireless machine to initiate a scan to
find the AP:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> up scan</userinput>
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS
freebsdap 00:11:95:c3:0d:ac 1 54M -66:-96 100 ES WME</screen>
<para>The client machine found the Access Point and can be
associated with it:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.2</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 00:11:95:d5:43:62
inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g
status: associated
ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7
scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7
roam:rate 5 protmode CTS wme burst</screen>
</sect3>
<sect3>
<title>WPA Host-based Access Point</title>
<para>This section will focus on setting up &os; Access Point
using the WPA security protocol. More details regarding WPA
and the configuration of WPA-based wireless clients can be
found in the <xref linkend="network-wireless-wpa">.</para>
<para>The <application>hostapd</application> daemon is used to
deal with client authentication and keys management on the
WPA enabled Access Point.</para>
<para>In the following, all the configuration operations will
be performed on the &os; machine acting as AP. Once the
AP is correctly working, <application>hostapd</application>
should be automatically enabled at boot with the following
line in <filename>/etc/rc.conf</filename>:</para>
<programlisting>hostapd_enable="YES"</programlisting>
<para>Before trying to configure
<application>hostapd</application>, be sure you have done
the basic settings introduced in the
<xref linkend="network-wireless-ap-basic">.</para>
<sect4>
<title>WPA-PSK</title>
<para>WPA-PSK is intended for small networks where the use
of an backend authentication server is not possible or
desired.</para>
<para>The configuration is done in the
<filename>/etc/hostapd.conf</filename> file:</para>
<programlisting>interface=wlan0 <co id="co-ap-wpapsk-iface">
debug=1 <co id="co-ap-wpapsk-dbug">
ctrl_interface=/var/run/hostapd <co id="co-ap-wpapsk-ciface">
ctrl_interface_group=wheel <co id="co-ap-wpapsk-cifacegrp">
ssid=freebsdap <co id="co-ap-wpapsk-ssid">
wpa=1 <co id="co-ap-wpapsk-wpa">
wpa_passphrase=freebsdmall <co id="co-ap-wpapsk-pass">
wpa_key_mgmt=WPA-PSK <co id="co-ap-wpapsk-kmgmt">
wpa_pairwise=CCMP TKIP <co id="co-ap-wpapsk-pwise"></programlisting>
<calloutlist>
<callout arearefs="co-ap-wpapsk-iface">
<para>This field indicates the wireless interface used
for the Access Point.</para>
</callout>
<callout arearefs="co-ap-wpapsk-dbug">
<para>This field sets the level of verbosity during the
execution of <application>hostapd</application>. A
value of <literal>1</literal> represents the minimal
level.</para>
</callout>
<callout arearefs="co-ap-wpapsk-ciface">
<para>The <literal>ctrl_interface</literal> field gives
the pathname of the directory used by
<application>hostapd</application> to stores its
domain socket files for the communication with
external programs such as &man.hostapd.cli.8;. The
default value is used here.</para>
</callout>
<callout arearefs="co-ap-wpapsk-cifacegrp">
<para>The <literal>ctrl_interface_group</literal> line
sets the group (here, it is the
<groupname>wheel</groupname> group) allowed to access
to the control interface files.</para>
</callout>
<callout arearefs="co-ap-wpapsk-ssid">
<para>This field sets the network name.</para>
</callout>
<callout arearefs="co-ap-wpapsk-wpa">
<para>The <literal>wpa</literal> field enables WPA and
specifies which WPA authentication protocol will be
required. A value of <literal>1</literal> configures
the AP for WPA-PSK.</para>
</callout>
<callout arearefs="co-ap-wpapsk-pass">
<para>The <literal>wpa_passphrase</literal> field
contains the ASCII passphrase for the WPA
authentication.</para>
<warning>
<para>Always use strong passwords that are
sufficiently long and made from a rich alphabet so
they will not be guessed and/or attacked.</para>
</warning>
</callout>
<callout arearefs="co-ap-wpapsk-kmgmt">
<para>The <literal>wpa_key_mgmt</literal> line refers to
the key management protocol we use. In our case it is
WPA-PSK.</para>
</callout>
<callout arearefs="co-ap-wpapsk-pwise">
<para>The <literal>wpa_pairwise</literal> field
indicates the set of accepted encryption algorithms by
the Access Point. Here both TKIP (WPA) and CCMP
(WPA2) ciphers are accepted. CCMP cipher is an
alternative to TKIP and that is strongly preferred
when possible; TKIP should be used solely for stations
incapable of doing CCMP.</para>
</callout>
</calloutlist>
<para>The next step is to start
<application>hostapd</application>:</para>
<screen>&prompt.root <userinput>/etc/rc.d/hostapd forcestart</userinput></screen>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 2290
inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
inet6 fe80::211:95ff:fec3:dac%ath0 prefixlen 64 scopeid 0x4
ether 00:11:95:c3:0d:ac
media: IEEE 802.11 Wireless Ethernet autoselect mode 11g &lt;hostap&gt;
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA2/802.11i privacy MIXED deftxkey 2 TKIP 2:128-bit txpowmax 36 protmode CTS dtimperiod 1 bintval 100</screen>
<para>The Access Point is running, the clients can now be
associated with it, see
<xref linkend="network-wireless-wpa"> for more details.
It is possible to see the stations associated with the AP
using the <command>ifconfig
<replaceable>wlan0</replaceable> list sta</command>
command.</para>
</sect4>
</sect3>
<sect3>
<title>WEP Host-based Access Point</title>
<para>It is not recommended to use WEP for setting up an
Access Point since there is no authentication mechanism and
it is easily to be cracked. Some legacy wireless cards only
support WEP as security protocol, these cards will only
allow to set up AP without authentication or encryption or
using the WEP protocol.</para>
<para>The wireless device can now be put into hostap mode and
configured with the correct SSID and IP address:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable> wlanmode hostap</userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable> \
ssid <replaceable>freebsdap</replaceable> wepmode on weptxkey <replaceable>3</replaceable> wepkey <replaceable>3:0x3456789012</replaceable> mode 11g</userinput></screen>
<itemizedlist>
<listitem>
<para>The <literal>weptxkey</literal> means which WEP
key will be used in the transmission. Here we used the
third key (note that the key numbering starts with
<literal>1</literal>). This parameter must be specified
to really encrypt the data.</para>
</listitem>
<listitem>
<para>The <literal>wepkey</literal> means setting the
selected WEP key. It should in the format
<replaceable>index:key</replaceable>, if the index is
not given, key <literal>1</literal> is set. That is
to say we need to set the index if we use keys other
than the first key.</para>
</listitem>
</itemizedlist>
<para>Use again <command>ifconfig</command> to see the status
of the <devicename>wlan0</devicename> interface:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable></userinput>
wlan0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 00:11:95:c3:0d:ac
inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
media: IEEE 802.11 Wireless Ethernet autoselect mode 11g &lt;hostap&gt;
status: running
ssid freebsdap channel 4 (2427 Mhz 11g) bssid 00:11:95:c3:0d:ac
country US ecm authmode OPEN privacy ON deftxkey 3 wepkey 3:40-bit
txpower 21.5 scanvalid 60 protmode CTS wme burst dtimperiod 1 -dfs</screen>
<para>From another wireless machine, it is possible to
initiate a scan to find the AP:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>ath0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> up scan</userinput>
SSID BSSID CHAN RATE S:N INT CAPS
freebsdap 00:11:95:c3:0d:ac 1 54M 22:1 100 EPS</screen>
<para>The client machine found the Access Point and can be
associated with it using the correct parameters (key, etc.),
see <xref linkend="network-wireless-wep"> for more
details.</para>
</sect3>
</sect2>
<sect2>
<title>Using Both Wired and Wireless Connection</title>
<para>Wired connection provides better performance and
reliability, while wireless connection provides flexibility
and mobility, users of laptop computers usually want to
combine these together and roam seamlessly between the
two.</para>
<para>On &os;, it is possible to combine two or even more
network interfaces together in a <quote>failover</quote>
fashion, that is, to use the most preferred and available
connection from a group of network interfaces, and have the
operating system switch automatically when the link state
changes.</para>
<para>We will cover link aggregation and failover in
<xref linkend="network-aggregation"> where an example for
using both wired and wireless connection is also provided at
<xref linkend="networking-lagg-wired-and-wireless">.</para>
</sect2>
<sect2>
<title>Troubleshooting</title>
<para>If you are having trouble with wireless networking, there
are a number of steps you can take to help troubleshoot the
problem.</para>
<itemizedlist>
<listitem>
<para>If you do not see the access point listed when
scanning be sure you have not configured your wireless
device to a limited set of channels.</para>
</listitem>
<listitem>
<para>If you cannot associate to an access point verify the
configuration of your station matches the one of the
access point. This includes the authentication scheme and
any security protocols. Simplify your configuration as
much as possible. If you are using a security protocol
such as WPA or WEP configure the access point for open
authentication and no security to see if you can get
traffic to pass.</para>
</listitem>
<listitem>
<para>Once you can associate to the access point diagnose
any security configuration using simple tools like
&man.ping.8;.</para>
<para>The <command>wpa_supplicant</command> has much
debugging support; try running it manually with the
<option>-dd</option> option and look at the system
logs.</para>
</listitem>
<listitem>
<para>There are also many lower-level debugging tools. You
can enable debugging messages in the 802.11 protocol
support layer using the <command>wlandebug</command>
program found in
<filename>/usr/src/tools/tools/net80211</filename>. For
example:</para>
<screen>&prompt.root; <userinput>wlandebug -i <replaceable>ath0</replaceable> +scan+auth+debug+assoc</userinput>
net.wlan.0.debug: 0 =&gt; 0xc80000&lt;assoc,auth,scan&gt;</screen>
<para>can be used to enable console messages related to
scanning for access points and doing the 802.11 protocol
handshakes required to arrange communication.</para>
<para>There are also many useful statistics maintained by
the 802.11 layer; the <command>wlanstats</command> tool
will dump this information. These statistics should
identify all errors identified by the 802.11 layer.
Beware however that some errors are identified in the
device drivers that lie below the 802.11 layer so they may
not show up. To diagnose device-specific problems you
need to refer to the drivers' documentation.</para>
</listitem>
</itemizedlist>
<para>If the above information does not help to clarify the
problem, please submit a problem report and include output
from the above tools.</para>
</sect2>
</sect1>
<sect1 id="network-bluetooth">
<sect1info>
<authorgroup>
<author>
<firstname>Pav</firstname>
<surname>Lucistnik</surname>
<contrib>Written by </contrib>
<affiliation>
<address><email>pav@FreeBSD.org</email></address>
</affiliation>
</author>
</authorgroup>
</sect1info>
<title>Bluetooth</title>
<indexterm><primary>Bluetooth</primary></indexterm>
<sect2>
<title>Introduction</title>
<para>Bluetooth is a wireless technology for creating personal
networks operating in the 2.4 GHz unlicensed band, with a
range of 10 meters. Networks are usually formed ad-hoc from
portable devices such as cellular phones, handhelds and
laptops. Unlike the other popular wireless technology, Wi-Fi,
Bluetooth offers higher level service profiles, e.g., FTP-like
file servers, file pushing, voice transport, serial line
emulation, and more.</para>
<para>The Bluetooth stack in &os; is implemented using the
Netgraph framework (see &man.netgraph.4;). A broad variety of
Bluetooth USB dongles is supported by the &man.ng.ubt.4;
driver. The Broadcom BCM2033 chip based Bluetooth devices are
supported via the &man.ubtbcmfw.4; and &man.ng.ubt.4; drivers.
The 3Com Bluetooth PC Card 3CRWB60-A is supported by the
&man.ng.bt3c.4; driver. Serial and UART based Bluetooth
devices are supported via &man.sio.4;, &man.ng.h4.4; and
&man.hcseriald.8;. This section describes the use of the USB
Bluetooth dongle.</para>
</sect2>
<sect2>
<title>Plugging in the Device</title>
<para>By default Bluetooth device drivers are available as
kernel modules. Before attaching a device, you will need to
load the driver into the kernel:</para>
<screen>&prompt.root; <userinput>kldload ng_ubt</userinput></screen>
<para>If the Bluetooth device is present in the system during
system startup, load the module from
<filename>/boot/loader.conf</filename>:</para>
<programlisting>ng_ubt_load="YES"</programlisting>
<para>Plug in your USB dongle. The output similar to the
following will appear on the console (or in syslog):</para>
<screen>ubt0: vendor 0x0a12 product 0x0001, rev 1.10/5.25, addr 2
ubt0: Interface 0 endpoints: interrupt=0x81, bulk-in=0x82, bulk-out=0x2
ubt0: Interface 1 (alt.config 5) endpoints: isoc-in=0x83, isoc-out=0x3,
wMaxPacketSize=49, nframes=6, buffer size=294</screen>
<para>The <filename>/etc/rc.d/bluetooth</filename> script
is used to start and stop the Bluetooth stack. It is a good
idea to stop the stack before unplugging the device, but it is
not (usually) fatal. When starting the stack, you will
receive output similar to the following:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/bluetooth start ubt0</userinput>
BD_ADDR: 00:02:72:00:d4:1a
Features: 0xff 0xff 0xf 00 00 00 00 00
&lt;3-Slot&gt; &lt;5-Slot&gt; &lt;Encryption&gt; &lt;Slot offset&gt;
&lt;Timing accuracy&gt; &lt;Switch&gt; &lt;Hold mode&gt; &lt;Sniff mode&gt;
&lt;Park mode&gt; &lt;RSSI&gt; &lt;Channel quality&gt; &lt;SCO link&gt;
&lt;HV2 packets&gt; &lt;HV3 packets&gt; &lt;u-law log&gt; &lt;A-law log&gt; &lt;CVSD&gt;
&lt;Paging scheme&gt; &lt;Power control&gt; &lt;Transparent SCO data&gt;
Max. ACL packet size: 192 bytes
Number of ACL packets: 8
Max. SCO packet size: 64 bytes
Number of SCO packets: 8</screen>
</sect2>
<indexterm><primary>HCI</primary></indexterm>
<sect2>
<title>Host Controller Interface (HCI)</title>
<para>Host Controller Interface (HCI) provides a command
interface to the baseband controller and link manager, and
access to hardware status and control registers. This
interface provides a uniform method of accessing the Bluetooth
baseband capabilities. HCI layer on the Host exchanges data
and commands with the HCI firmware on the Bluetooth hardware.
The Host Controller Transport Layer (i.e., physical bus)
driver provides both HCI layers with the ability to exchange
information with each other.</para>
<para>A single Netgraph node of type <emphasis>hci</emphasis> is
created for a single Bluetooth device. The HCI node is
normally connected to the Bluetooth device driver node
(downstream) and the L2CAP node (upstream). All HCI
operations must be performed on the HCI node and not on the
device driver node. Default name for the HCI node is
<quote>devicehci</quote>. For more details refer to the
&man.ng.hci.4; manual page.</para>
<para>One of the most common tasks is discovery of Bluetooth
devices in RF proximity. This operation is called
<emphasis>inquiry</emphasis>. Inquiry and other HCI related
operations are done with the &man.hccontrol.8; utility. The
example below shows how to find out which Bluetooth devices
are in range. You should receive the list of devices in a few
seconds. Note that a remote device will only answer the
inquiry if it put into <emphasis>discoverable</emphasis>
mode.</para>
<screen>&prompt.user; <userinput>hccontrol -n ubt0hci inquiry</userinput>
Inquiry result, num_responses=1
Inquiry result #0
BD_ADDR: 00:80:37:29:19:a4
Page Scan Rep. Mode: 0x1
Page Scan Period Mode: 00
Page Scan Mode: 00
Class: 52:02:04
Clock offset: 0x78ef
Inquiry complete. Status: No error [00]</screen>
<para><literal>BD_ADDR</literal> is unique address of a
Bluetooth device, similar to MAC addresses of a network card.
This address is needed for further communication with a
device. It is possible to assign human readable name to a
BD_ADDR. The <filename>/etc/bluetooth/hosts</filename> file
contains information regarding the known Bluetooth hosts. The
following example shows how to obtain human readable name that
was assigned to the remote device:</para>
<screen>&prompt.user; <userinput>hccontrol -n ubt0hci remote_name_request 00:80:37:29:19:a4</userinput>
BD_ADDR: 00:80:37:29:19:a4
Name: Pav's T39</screen>
<para>If you perform an inquiry on a remote Bluetooth device, it
will find your computer as
<quote>your.host.name (ubt0)</quote>. The name assigned to the
local device can be changed at any time.</para>
<para>The Bluetooth system provides a point-to-point connection
(only two Bluetooth units involved), or a point-to-multipoint
connection. In the point-to-multipoint connection the
connection is shared among several Bluetooth devices. The
following example shows how to obtain the list of active
baseband connections for the local device:</para>
<screen>&prompt.user; <userinput>hccontrol -n ubt0hci read_connection_list</userinput>
Remote BD_ADDR Handle Type Mode Role Encrypt Pending Queue State
00:80:37:29:19:a4 41 ACL 0 MAST NONE 0 0 OPEN</screen>
<para>A <emphasis>connection handle</emphasis> is useful when
termination of the baseband connection is required. Note,
that it is normally not required to do it by hand. The stack
will automatically terminate inactive baseband
connections.</para>
<screen>&prompt.root; <userinput>hccontrol -n ubt0hci disconnect 41</userinput>
Connection handle: 41
Reason: Connection terminated by local host [0x16]</screen>
<para>Refer to <command>hccontrol help</command> for a complete
listing of available HCI commands. Most of the HCI commands
do not require superuser privileges.</para>
</sect2>
<indexterm><primary>L2CAP</primary></indexterm>
<sect2>
<title>Logical Link Control and Adaptation Protocol
(L2CAP)</title>
<para>Logical Link Control and Adaptation Protocol (L2CAP)
provides connection-oriented and connectionless data services
to upper layer protocols with protocol multiplexing capability
and segmentation and reassembly operation. L2CAP permits
higher level protocols and applications to transmit and
receive L2CAP data packets up to 64 kilobytes in
length.</para>
<para>L2CAP is based around the concept of
<emphasis>channels</emphasis>. Channel is a logical
connection on top of baseband connection. Each channel is
bound to a single protocol in a many-to-one fashion. Multiple
channels can be bound to the same protocol, but a channel
cannot be bound to multiple protocols. Each L2CAP packet
received on a channel is directed to the appropriate higher
level protocol. Multiple channels can share the same baseband
connection.</para>
<para>A single Netgraph node of type <emphasis>l2cap</emphasis>
is created for a single Bluetooth device. The L2CAP node is
normally connected to the Bluetooth HCI node (downstream) and
Bluetooth sockets nodes (upstream). Default name for the
L2CAP node is <quote>devicel2cap</quote>. For more details
refer to the &man.ng.l2cap.4; manual page.</para>
<para>A useful command is &man.l2ping.8;, which can be used to
ping other devices. Some Bluetooth implementations might not
return all of the data sent to them, so
<literal>0 bytes</literal> in the following example is
normal.</para>
<screen>&prompt.root; <userinput>l2ping -a 00:80:37:29:19:a4</userinput>
0 bytes from 0:80:37:29:19:a4 seq_no=0 time=48.633 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=1 time=37.551 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=2 time=28.324 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=3 time=46.150 ms result=0</screen>
<para>The &man.l2control.8; utility is used to perform various
operations on L2CAP nodes. This example shows how to obtain
the list of logical connections (channels) and the list of
baseband connections for the local device:</para>
<screen>&prompt.user; <userinput>l2control -a 00:02:72:00:d4:1a read_channel_list</userinput>
L2CAP channels:
Remote BD_ADDR SCID/ DCID PSM IMTU/ OMTU State
00:07:e0:00:0b:ca 66/ 64 3 132/ 672 OPEN
&prompt.user; <userinput>l2control -a 00:02:72:00:d4:1a read_connection_list</userinput>
L2CAP connections:
Remote BD_ADDR Handle Flags Pending State
00:07:e0:00:0b:ca 41 O 0 OPEN</screen>
<para>Another diagnostic tool is &man.btsockstat.1;. It does a
job similar to as &man.netstat.1; does, but for Bluetooth
network-related data structures. The example below shows the
same logical connection as &man.l2control.8; above.</para>
<screen>&prompt.user; <userinput>btsockstat</userinput>
Active L2CAP sockets
PCB Recv-Q Send-Q Local address/PSM Foreign address CID State
c2afe900 0 0 00:02:72:00:d4:1a/3 00:07:e0:00:0b:ca 66 OPEN
Active RFCOMM sessions
L2PCB PCB Flag MTU Out-Q DLCs State
c2afe900 c2b53380 1 127 0 Yes OPEN
Active RFCOMM sockets
PCB Recv-Q Send-Q Local address Foreign address Chan DLCI State
c2e8bc80 0 250 00:02:72:00:d4:1a 00:07:e0:00:0b:ca 3 6 OPEN</screen>
</sect2>
<indexterm><primary>RFCOMM</primary></indexterm>
<sect2>
<title>RFCOMM Protocol</title>
<para>The RFCOMM protocol provides emulation of serial ports
over the L2CAP protocol. The protocol is based on the ETSI
standard TS 07.10. RFCOMM is a simple transport protocol,
with additional provisions for emulating the 9 circuits of
RS-232 (EIATIA-232-E) serial ports. The RFCOMM protocol
supports up to 60 simultaneous connections (RFCOMM channels)
between two Bluetooth devices.</para>
<para>For the purposes of RFCOMM, a complete communication path
involves two applications running on different devices (the
communication endpoints) with a communication segment between
them. RFCOMM is intended to cover applications that make use
of the serial ports of the devices in which they reside. The
communication segment is a Bluetooth link from one device to
another (direct connect).</para>
<para>RFCOMM is only concerned with the connection between the
devices in the direct connect case, or between the device and
a modem in the network case. RFCOMM can support other
configurations, such as modules that communicate via Bluetooth
wireless technology on one side and provide a wired interface
on the other side.</para>
<para>In &os; the RFCOMM protocol is implemented at the
Bluetooth sockets layer.</para>
</sect2>
<indexterm><primary>pairing</primary></indexterm>
<sect2>
<title>Pairing of Devices</title>
<para>By default, Bluetooth communication is not authenticated,
and any device can talk to any other device. A Bluetooth
device (for example, cellular phone) may choose to require
authentication to provide a particular service (for example,
Dial-Up service). Bluetooth authentication is normally done
with <emphasis>PIN codes</emphasis>. A PIN code is an ASCII
string up to 16 characters in length. User is required to
enter the same PIN code on both devices. Once user has
entered the PIN code, both devices will generate a
<emphasis>link key</emphasis>. After that the link key can be
stored either in the devices themselves or in a persistent
storage. Next time both devices will use previously generated
link key. The described above procedure is called
<emphasis>pairing</emphasis>. Note that if the link key is
lost by any device then pairing must be repeated.</para>
<para>The &man.hcsecd.8; daemon is responsible for handling of
all Bluetooth authentication requests. The default
configuration file is
<filename>/etc/bluetooth/hcsecd.conf</filename>. An example
section for a cellular phone with the PIN code arbitrarily set
to <quote>1234</quote> is shown below:</para>
<programlisting>device {
bdaddr 00:80:37:29:19:a4;
name "Pav's T39";
key nokey;
pin "1234";
}</programlisting>
<para>There is no limitation on PIN codes (except length). Some
devices (for example Bluetooth headsets) may have a fixed PIN
code built in. The <option>-d</option> switch forces the
&man.hcsecd.8; daemon to stay in the foreground, so it is easy
to see what is happening. Set the remote device to receive
pairing and initiate the Bluetooth connection to the remote
device. The remote device should say that pairing was
accepted, and request the PIN code. Enter the same PIN code
as you have in <filename>hcsecd.conf</filename>. Now your PC
and the remote device are paired. Alternatively, you can
initiate pairing on the remote device.</para>
<para>The following line can be added to the
<filename>/etc/rc.conf</filename> file to have
<application>hcsecd</application> started automatically on
system start:</para>
<programlisting>hcsecd_enable="YES"</programlisting>
<para>The following is a sample of the
<application>hcsecd</application> daemon output:</para>
<programlisting>hcsecd[16484]: Got Link_Key_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', link key doesn't exist
hcsecd[16484]: Sending Link_Key_Negative_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Got PIN_Code_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', PIN code exists
hcsecd[16484]: Sending PIN_Code_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4</programlisting>
</sect2>
<indexterm><primary>SDP</primary></indexterm>
<sect2>
<title>Service Discovery Protocol (SDP)</title>
<para>The Service Discovery Protocol (SDP) provides the means
for client applications to discover the existence of services
provided by server applications as well as the attributes of
those services. The attributes of a service include the type
or class of service offered and the mechanism or protocol
information needed to utilize the service.</para>
<para>SDP involves communication between a SDP server and a SDP
client. The server maintains a list of service records that
describe the characteristics of services associated with the
server. Each service record contains information about a
single service. A client may retrieve information from a
service record maintained by the SDP server by issuing a SDP
request. If the client, or an application associated with the
client, decides to use a service, it must open a separate
connection to the service provider in order to utilize the
service. SDP provides a mechanism for discovering services
and their attributes, but it does not provide a mechanism for
utilizing those services.</para>
<para>Normally, a SDP client searches for services based on some
desired characteristics of the services. However, there are
times when it is desirable to discover which types of services
are described by an SDP server's service records without any a
priori information about the services. This process of
looking for any offered services is called
<emphasis>browsing</emphasis>.</para>
<para>The Bluetooth SDP server &man.sdpd.8; and command line
client &man.sdpcontrol.8; are included in the standard &os;
installation. The following example shows how to perform a
SDP browse query.</para>
<screen>&prompt.user; <userinput>sdpcontrol -a 00:01:03:fc:6e:ec browse</userinput>
Record Handle: 00000000
Service Class ID List:
Service Discovery Server (0x1000)
Protocol Descriptor List:
L2CAP (0x0100)
Protocol specific parameter #1: u/int/uuid16 1
Protocol specific parameter #2: u/int/uuid16 1
Record Handle: 0x00000001
Service Class ID List:
Browse Group Descriptor (0x1001)
Record Handle: 0x00000002
Service Class ID List:
LAN Access Using PPP (0x1102)
Protocol Descriptor List:
L2CAP (0x0100)
RFCOMM (0x0003)
Protocol specific parameter #1: u/int8/bool 1
Bluetooth Profile Descriptor List:
LAN Access Using PPP (0x1102) ver. 1.0</screen>
<para>... and so on. Note that each service has a list of
attributes (RFCOMM channel for example). Depending on the
service you might need to make a note of some of the
attributes. Some Bluetooth implementations do not support
service browsing and may return an empty list. In this case
it is possible to search for the specific service. The
example below shows how to search for the OBEX Object Push
(OPUSH) service:</para>
<screen>&prompt.user; <userinput>sdpcontrol -a 00:01:03:fc:6e:ec search OPUSH</userinput></screen>
<para>Offering services on &os; to Bluetooth clients is done
with the &man.sdpd.8; server. The following line can be added
to the <filename>/etc/rc.conf</filename> file:</para>
<programlisting>sdpd_enable="YES"</programlisting>
<para>Then the <application>sdpd</application> daemon can be
started with:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/sdpd start</userinput></screen>
<para>The local server application that wants to provide
Bluetooth service to the remote clients will register service
with the local SDP daemon. The example of such application is
&man.rfcomm.pppd.8;. Once started it will register Bluetooth
LAN service with the local SDP daemon.</para>
<para>The list of services registered with the local SDP server
can be obtained by issuing SDP browse query via local control
channel:</para>
<screen>&prompt.root; <userinput>sdpcontrol -l browse</userinput></screen>
</sect2>
<sect2>
<title>Dial-Up Networking (DUN) and Network Access with PPP
(LAN) Profiles</title>
<para>The Dial-Up Networking (DUN) profile is mostly used with
modems and cellular phones. The scenarios covered by this
profile are the following:</para>
<itemizedlist>
<listitem>
<para>use of a cellular phone or modem by a computer as a
wireless modem for connecting to a dial-up Internet access
server, or using other dial-up services;</para>
</listitem>
<listitem>
<para>use of a cellular phone or modem by a computer to
receive data calls.</para>
</listitem>
</itemizedlist>
<para>Network Access with PPP (LAN) profile can be used in the
following situations:</para>
<itemizedlist>
<listitem>
<para>LAN access for a single Bluetooth device;</para>
</listitem>
<listitem>
<para>LAN access for multiple Bluetooth devices;</para>
</listitem>
<listitem>
<para>PC to PC (using PPP networking over serial cable
emulation).</para>
</listitem>
</itemizedlist>
<para>In &os; both profiles are implemented with &man.ppp.8; and
&man.rfcomm.pppd.8; - a wrapper that converts RFCOMM Bluetooth
connection into something PPP can operate with. Before any
profile can be used, a new PPP label in the
<filename>/etc/ppp/ppp.conf</filename> must be created.
Consult &man.rfcomm.pppd.8; manual page for examples.</para>
<para>In the following example &man.rfcomm.pppd.8; will be used
to open RFCOMM connection to remote device with BD_ADDR
00:80:37:29:19:a4 on DUN RFCOMM channel. The actual RFCOMM
channel number will be obtained from the remote device via
SDP. It is possible to specify RFCOMM channel by hand, and in
this case &man.rfcomm.pppd.8; will not perform SDP query. Use
&man.sdpcontrol.8; to find out RFCOMM channel on the remote
device.</para>
<screen>&prompt.root; <userinput>rfcomm_pppd -a 00:80:37:29:19:a4 -c -C dun -l rfcomm-dialup</userinput></screen>
<para>In order to provide Network Access with PPP (LAN) service
the &man.sdpd.8; server must be running. A new entry for LAN
clients must be created in the
<filename>/etc/ppp/ppp.conf</filename> file. Consult
&man.rfcomm.pppd.8; manual page for examples. Finally, start
RFCOMM PPP server on valid RFCOMM channel number. The RFCOMM
PPP server will automatically register Bluetooth LAN service
with the local SDP daemon. The example below shows how to
start RFCOMM PPP server.</para>
<screen>&prompt.root; <userinput>rfcomm_pppd -s -C 7 -l rfcomm-server</userinput></screen>
</sect2>
<indexterm><primary>OBEX</primary></indexterm>
<sect2>
<title>OBEX Object Push (OPUSH) Profile</title>
<para>OBEX is a widely used protocol for simple file transfers
between mobile devices. Its main use is in infrared
communication, where it is used for generic file transfers
between notebooks or PDAs, and for sending business cards or
calendar entries between cellular phones and other devices
with PIM applications.</para>
<para>The OBEX server and client are implemented as a
third-party package <application>obexapp</application>, which
is available as <filename
role="package">comms/obexapp</filename> port.</para>
<para>OBEX client is used to push and/or pull objects from the
OBEX server. An object can, for example, be a business card
or an appointment. The OBEX client can obtain RFCOMM channel
number from the remote device via SDP. This can be done by
specifying service name instead of RFCOMM channel number.
Supported service names are: IrMC, FTRN and OPUSH. It is
possible to specify RFCOMM channel as a number. Below is an
example of an OBEX session, where device information object is
pulled from the cellular phone, and a new object (business
card) is pushed into the phone's directory.</para>
<screen>&prompt.user; <userinput>obexapp -a 00:80:37:29:19:a4 -C IrMC</userinput>
obex&gt; get telecom/devinfo.txt devinfo-t39.txt
Success, response: OK, Success (0x20)
obex&gt; put new.vcf
Success, response: OK, Success (0x20)
obex&gt; di
Success, response: OK, Success (0x20)</screen>
<para>In order to provide OBEX Object Push service, &man.sdpd.8;
server must be running. A root folder, where all incoming
objects will be stored, must be created. The default path to
the root folder is <filename>/var/spool/obex</filename>.
Finally, start OBEX server on valid RFCOMM channel number.
The OBEX server will automatically register OBEX Object Push
service with the local SDP daemon. The example below shows
how to start OBEX server.</para>
<screen>&prompt.root; <userinput>obexapp -s -C 10</userinput></screen>
</sect2>
<sect2>
<title>Serial Port Profile (SPP)</title>
<para>The Serial Port Profile (SPP) allows Bluetooth devices to
perform RS232 (or similar) serial cable emulation. The
scenario covered by this profile deals with legacy
applications using Bluetooth as a cable replacement, through a
virtual serial port abstraction.</para>
<para>The &man.rfcomm.sppd.1; utility implements the Serial Port
profile. A pseudo tty is used as a virtual serial port
abstraction. The example below shows how to connect to a
remote device Serial Port service. Note that you do not have
to specify a RFCOMM channel - &man.rfcomm.sppd.1; can obtain
it from the remote device via SDP. If you would like to
override this, specify a RFCOMM channel on the command
line.</para>
<screen>&prompt.root; <userinput>rfcomm_sppd -a 00:07:E0:00:0B:CA -t /dev/ttyp6</userinput>
rfcomm_sppd[94692]: Starting on /dev/ttyp6...</screen>
<para>Once connected, the pseudo tty can be used as serial
port:</para>
<screen>&prompt.root; <userinput>cu -l ttyp6</userinput></screen>
</sect2>
<sect2>
<title>Troubleshooting</title>
<sect3>
<title>A Remote Device Cannot Connect</title>
<para>Some older Bluetooth devices do not support role
switching. By default, when &os; is accepting a new
connection, it tries to perform a role switch and become
master. Devices, which do not support this will not be able
to connect. Note that role switching is performed when a
new connection is being established, so it is not possible
to ask the remote device if it does support role switching.
There is a HCI option to disable role switching on the local
side:</para>
<screen>&prompt.root; <userinput>hccontrol -n ubt0hci write_node_role_switch 0</userinput></screen>
</sect3>
<sect3>
<title>Something is Going Wrong, Can I See What Exactly is
Happening?</title>
<para>Yes, you can. Use the third-party package
<application>hcidump</application>, which is available as
<filename role="package">comms/hcidump</filename> port. The
<application>hcidump</application> utility is similar to
&man.tcpdump.1;. It can be used to display the content of
the Bluetooth packets on the terminal and to dump the
Bluetooth packets to a file.</para>
</sect3>
</sect2>
</sect1>
<sect1 id="network-bridging">
<sect1info>
<authorgroup>
<author>
<firstname>Andrew</firstname>
<surname>Thompson</surname>
<contrib>Written by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Bridging</title>
<sect2>
<title>Introduction</title>
<indexterm><primary>IP subnet</primary></indexterm>
<indexterm><primary>bridge</primary></indexterm>
<para>It is sometimes useful to divide one physical network
(such as an Ethernet segment) into two separate network
segments without having to create IP subnets and use a router
to connect the segments together. A device that connects two
networks together in this fashion is called a
<quote>bridge</quote>. A FreeBSD system with two network
interface cards can act as a bridge.</para>
<para>The bridge works by learning the MAC layer addresses
(Ethernet addresses) of the devices on each of its network
interfaces. It forwards traffic between two networks only
when its source and destination are on different
networks.</para>
<para>In many respects, a bridge is like an Ethernet switch with
very few ports.</para>
</sect2>
<sect2>
<title>Situations Where Bridging Is Appropriate</title>
<para>There are many common situations in which a bridge is used
today.</para>
<sect3>
<title>Connecting Networks</title>
<para>The basic operation of a bridge is to join two or more
network segments together. There are many reasons to use a
host based bridge over plain networking equipment such as
cabling constraints, firewalling or connecting pseudo
networks such as a Virtual Machine interface. A bridge can
also connect a wireless interface running in hostap mode to
a wired network and act as an access point.</para>
</sect3>
<sect3>
<title>Filtering/Traffic Shaping Firewall</title>
<indexterm><primary>firewall</primary></indexterm>
<indexterm><primary>NAT</primary></indexterm>
<para>A common situation is where firewall functionality is
needed without routing or network address translation
(NAT).</para>
<para>An example is a small company that is connected via DSL
or ISDN to their ISP. They have a 13 globally-accessible IP
addresses from their ISP and have 10 PCs on their network.
In this situation, using a router-based firewall is
difficult because of subnetting issues.</para>
<indexterm><primary>router</primary></indexterm>
<indexterm><primary>DSL</primary></indexterm>
<indexterm><primary>ISDN</primary></indexterm>
<para>A bridge-based firewall can be configured and dropped
into the path just downstream of their DSL/ISDN router
without any IP numbering issues.</para>
</sect3>
<sect3>
<title>Network Tap</title>
<para>A bridge can join two network segments and be used to
inspect all Ethernet frames that pass between them. This
can either be from using &man.bpf.4;/&man.tcpdump.1; on the
bridge interface or by sending a copy of all frames out an
additional interface (span port).</para>
</sect3>
<sect3>
<title>Layer 2 VPN</title>
<para>Two Ethernet networks can be joined across an IP link by
bridging the networks to an EtherIP tunnel or a &man.tap.4;
based solution such as OpenVPN.</para>
</sect3>
<sect3>
<title>Layer 2 Redundancy</title>
<para>A network can be connected together with multiple links
and use the Spanning Tree Protocol to block redundant paths.
For an Ethernet network to function properly only one active
path can exist between two devices, Spanning Tree will
detect loops and put the redundant links into a blocked
state. Should one of the active links fail then the
protocol will calculate a different tree and reenable one of
the blocked paths to restore connectivity to all points in
the network.</para>
</sect3>
</sect2>
<sect2>
<title>Kernel Configuration</title>
<para>This section covers &man.if.bridge.4; bridge
implementation, a netgraph bridging driver is also available,
for more information see &man.ng.bridge.4; manual page.</para>
<para>The bridge driver is a kernel module and will be
automatically loaded by &man.ifconfig.8; when creating a
bridge interface. It is possible to compile the bridge in to
the kernel by adding <literal>device if_bridge</literal> to
your kernel configuration file.</para>
<para>Packet filtering can be used with any firewall package
that hooks in via the &man.pfil.9; framework. The firewall
can be loaded as a module or compiled into the kernel.</para>
<para>The bridge can be used as a traffic shaper with
&man.altq.4; or &man.dummynet.4;.</para>
</sect2>
<sect2>
<title>Enabling the Bridge</title>
<para>The bridge is created using interface cloning. To create
a bridge use &man.ifconfig.8;, if the bridge driver is not
present in the kernel then it will be loaded
automatically.</para>
<screen>&prompt.root; <userinput>ifconfig bridge create</userinput>
bridge0
&prompt.root; <userinput>ifconfig bridge0</userinput>
bridge0: flags=8802&lt;BROADCAST,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 96:3d:4b:f1:79:7a
id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
root id 00:00:00:00:00:00 priority 0 ifcost 0 port 0</screen>
<para>A bridge interface is created and is automatically
assigned a randomly generated Ethernet address. The
<literal>maxaddr</literal> and <literal>timeout</literal>
parameters control how many MAC addresses the bridge will keep
in its forwarding table and how many seconds before each entry
is removed after it is last seen. The other parameters
control how Spanning Tree operates.</para>
<para>Add the member network interfaces to the bridge. For the
bridge to forward packets all member interfaces and the bridge
need to be up:</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 addm fxp0 addm fxp1 up</userinput>
&prompt.root; <userinput>ifconfig fxp0 up</userinput>
&prompt.root; <userinput>ifconfig fxp1 up</userinput></screen>
<para>The bridge is now forwarding Ethernet frames between
<devicename>fxp0</devicename> and
<devicename>fxp1</devicename>. The equivalent configuration
in <filename>/etc/rc.conf</filename> so the bridge is created
at startup is:</para>
<programlisting>cloned_interfaces="bridge0"
ifconfig_bridge0="addm fxp0 addm fxp1 up"
ifconfig_fxp0="up"
ifconfig_fxp1="up"</programlisting>
<para>If the bridge host needs an IP address then the correct
place to set this is on the bridge interface itself rather
than one of the member interfaces. This can be set statically
or via DHCP:</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 inet 192.168.0.1/24</userinput></screen>
<para>It is also possible to assign an IPv6 address to a bridge
interface.</para>
</sect2>
<sect2>
<title>Firewalling</title>
<indexterm><primary>firewall</primary></indexterm>
<para>When packet filtering is enabled, bridged packets will
pass through the filter inbound on the originating interface,
on the bridge interface and outbound on the appropriate
interfaces. Either stage can be disabled. When direction of
the packet flow is important it is best to firewall on the
member interfaces rather than the bridge itself.</para>
<para>The bridge has several configurable settings for passing
non-IP and ARP packets, and layer2 firewalling with IPFW. See
&man.if.bridge.4; for more information.</para>
</sect2>
<sect2>
<title>Spanning Tree</title>
<para>The bridge driver implements the Rapid Spanning Tree
Protocol (RSTP or 802.1w) with backwards compatibility with
the legacy Spanning Tree Protocol (STP). Spanning Tree is
used to detect and remove loops in a network topology. RSTP
provides faster Spanning Tree convergence than legacy STP, the
protocol will exchange information with neighbouring switches
to quickly transition to forwarding without creating
loops.
&os; supports RSTP and STP as operating modes, with RSTP
being the default mode.</para>
<para>Spanning Tree can be enabled on member interfaces using
the <literal>stp</literal> command. For a bridge with
<devicename>fxp0</devicename> and
<devicename>fxp1</devicename> as the current interfaces,
enable STP with the following:</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 stp fxp0 stp fxp1</userinput>
bridge0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether d6:cf:d5:a0:94:6d
id 00:01:02:4b:d4:50 priority 32768 hellotime 2 fwddelay 15
maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
root id 00:01:02:4b:d4:50 priority 32768 ifcost 0 port 0
member: fxp0 flags=1c7&lt;LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP&gt;
port 3 priority 128 path cost 200000 proto rstp
role designated state forwarding
member: fxp1 flags=1c7&lt;LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP&gt;
port 4 priority 128 path cost 200000 proto rstp
role designated state forwarding</screen>
<para>This bridge has a spanning tree ID of
<literal>00:01:02:4b:d4:50</literal> and a priority of
<literal>32768</literal>. As the <literal>root id</literal>
is the same it indicates that this is the root bridge for the
tree.</para>
<para>Another bridge on the network also has spanning tree
enabled:</para>
<screen>bridge0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
ether 96:3d:4b:f1:79:7a
id 00:13:d4:9a:06:7a priority 32768 hellotime 2 fwddelay 15
maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200
root id 00:01:02:4b:d4:50 priority 32768 ifcost 400000 port 4
member: fxp0 flags=1c7&lt;LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP&gt;
port 4 priority 128 path cost 200000 proto rstp
role root state forwarding
member: fxp1 flags=1c7&lt;LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP&gt;
port 5 priority 128 path cost 200000 proto rstp
role designated state forwarding</screen>
<para>The line <literal>root id 00:01:02:4b:d4:50 priority 32768
ifcost 400000 port 4</literal> shows that the root bridge is
<literal>00:01:02:4b:d4:50</literal> as above and has a path
cost of <literal>400000</literal> from this bridge, the path
to the root bridge is via <literal>port 4</literal> which is
<devicename>fxp0</devicename>.</para>
</sect2>
<sect2>
<title>Advanced Bridging</title>
<sect3>
<title>Reconstruct Traffic Flows</title>
<para>The bridge supports monitor mode, where the packets are
discarded after &man.bpf.4; processing, and are not
processed or forwarded further. This can be used to
multiplex the input of two or more interfaces into a single
&man.bpf.4; stream. This is useful for reconstructing the
traffic for network taps that transmit the RX/TX signals out
through two separate interfaces.</para>
<para>To read the input from four network interfaces as one
stream:</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 addm fxp0 addm fxp1 addm fxp2 addm fxp3 monitor up</userinput>
&prompt.root; <userinput>tcpdump -i bridge0</userinput></screen>
</sect3>
<sect3>
<title>Span Ports</title>
<para>A copy of every Ethernet frame received by the bridge
will be transmitted out a designated span port. The number
of span ports configured on a bridge is unlimited, if an
interface is designated as a span port then it may not also
be used as a regular bridge port. This is most useful for
snooping a bridged network passively on another host
connected to one of the span ports of the bridge.</para>
<para>To send a copy of all frames out the interface named
<devicename>fxp4</devicename>:</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 span fxp4</userinput></screen>
</sect3>
<sect3>
<title>Private Interfaces</title>
<para>A private interface does not forward any traffic to any
other port that is also a private interface. The traffic is
blocked unconditionally so no Ethernet frames will be
forwarded, including ARP. If traffic needs to be
selectively blocked then a firewall should be used
instead.</para>
</sect3>
<sect3>
<title>Sticky Interfaces</title>
<para>If a bridge member interface is marked as sticky then
dynamically learned address entries are treated at static
once entered into the forwarding cache. Sticky entries are
never aged out of the cache or replaced, even if the address
is seen on a different interface. This gives the benefit of
static address entries without the need to pre-populate the
forwarding table, clients learnt on a particular segment of
the bridge can not roam to another segment.</para>
<para>Another example of using sticky addresses would be to
combine the bridge with VLANs to create a router where
customer networks are isolated without wasting IP address
space. Consider that
<hostid role="Hostname">CustomerA</hostid> is on
<literal>vlan100</literal> and
<hostid role="hostname">CustomerB</hostid> is on
<literal>vlan101</literal>. The bridge has the address
<hostid role="ipaddr">192.168.0.1</hostid> and is also an
internet router.</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 addm vlan100 sticky vlan100 addm vlan101 sticky vlan101</userinput>
&prompt.root; <userinput>ifconfig bridge0 inet 192.168.0.1/24</userinput></screen>
<para>Both clients see
<hostid role="ipaddr">192.168.0.1</hostid> as their default
gateway and since the bridge cache is sticky they can not
spoof the MAC address of the other customer to intercept
their traffic.</para>
<para>Any communication between the VLANs can be blocked using
private interfaces (or a firewall):</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 private vlan100 private vlan101</userinput></screen>
<para>The customers are completely isolated from each other,
the full <hostid role="netmask">/24</hostid> address range
can be allocated without subnetting.</para>
</sect3>
<sect3>
<title>Address Limits</title>
<para>The number of unique source MAC addresses behind an
interface can be limited. Once the limit is reached packets
with unknown source addresses are dropped until an
existing host cache entry expires or is removed.</para>
<para>The following example sets the maximum number of
Ethernet devices for
<hostid role="Hostname">CustomerA</hostid> on
<literal>vlan100</literal> to 10.</para>
<screen>&prompt.root; <userinput>ifconfig bridge0 ifmaxaddr vlan100 10</userinput></screen>
</sect3>
<sect3>
<title>SNMP Monitoring</title>
<para>The bridge interface and STP parameters can be monitored
via the SNMP daemon which is included in the &os; base
system. The exported bridge MIBs conform to the IETF
standards so any SNMP client or monitoring package can be
used to retrieve the data.</para>
<para>On the bridge machine uncomment the
<literal>begemotSnmpdModulePath."bridge" =
"/usr/lib/snmp_bridge.so"</literal> line from
<filename>/etc/snmp.config</filename> and start the
<application>bsnmpd</application> daemon. Other
configuration such as community names and access lists may
need to be modified. See &man.bsnmpd.1; and
&man.snmp.bridge.3; for more information.</para>
<para>The following examples use the
<application>Net-SNMP</application> software
(<filename role="package">net-mgmt/net-snmp</filename>) to
query a bridge, the
<filename role="package">net-mgmt/bsnmptools</filename> port
can also be used. From the SNMP client host add to
<filename>$HOME/.snmp/snmp.conf</filename> the following
lines to import the bridge MIB definitions in to
<application>Net-SNMP</application>:</para>
<programlisting>mibdirs +/usr/share/snmp/mibs
mibs +BRIDGE-MIB:RSTP-MIB:BEGEMOT-MIB:BEGEMOT-BRIDGE-MIB</programlisting>
<para>To monitor a single bridge via the IETF BRIDGE-MIB
(RFC4188) do</para>
<screen>&prompt.user; <userinput>snmpwalk -v 2c -c public bridge1.example.com mib-2.dot1dBridge</userinput>
BRIDGE-MIB::dot1dBaseBridgeAddress.0 = STRING: 66:fb:9b:6e:5c:44
BRIDGE-MIB::dot1dBaseNumPorts.0 = INTEGER: 1 ports
BRIDGE-MIB::dot1dStpTimeSinceTopologyChange.0 = Timeticks: (189959) 0:31:39.59 centi-seconds
BRIDGE-MIB::dot1dStpTopChanges.0 = Counter32: 2
BRIDGE-MIB::dot1dStpDesignatedRoot.0 = Hex-STRING: 80 00 00 01 02 4B D4 50
...
BRIDGE-MIB::dot1dStpPortState.3 = INTEGER: forwarding(5)
BRIDGE-MIB::dot1dStpPortEnable.3 = INTEGER: enabled(1)
BRIDGE-MIB::dot1dStpPortPathCost.3 = INTEGER: 200000
BRIDGE-MIB::dot1dStpPortDesignatedRoot.3 = Hex-STRING: 80 00 00 01 02 4B D4 50
BRIDGE-MIB::dot1dStpPortDesignatedCost.3 = INTEGER: 0
BRIDGE-MIB::dot1dStpPortDesignatedBridge.3 = Hex-STRING: 80 00 00 01 02 4B D4 50
BRIDGE-MIB::dot1dStpPortDesignatedPort.3 = Hex-STRING: 03 80
BRIDGE-MIB::dot1dStpPortForwardTransitions.3 = Counter32: 1
RSTP-MIB::dot1dStpVersion.0 = INTEGER: rstp(2)</screen>
<para>The <literal>dot1dStpTopChanges.0</literal> value is two
which means that the STP bridge topology has changed twice,
a topology change means that one or more links in the
network have changed or failed and a new tree has been
calculated. The
<literal>dot1dStpTimeSinceTopologyChange.0</literal> value
will show when this happened.</para>
<para>To monitor multiple bridge interfaces one may use the
private BEGEMOT-BRIDGE-MIB:</para>
<screen>&prompt.user; <userinput>snmpwalk -v 2c -c public bridge1.example.com</userinput>
enterprises.fokus.begemot.begemotBridge
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge0" = STRING: bridge0
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge2" = STRING: bridge2
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge0" = STRING: e:ce:3b:5a:9e:13
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge2" = STRING: 12:5e:4d:74:d:fc
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge0" = INTEGER: 1
BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge2" = INTEGER: 1
...
BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge0" = Timeticks: (116927) 0:19:29.27 centi-seconds
BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge2" = Timeticks: (82773) 0:13:47.73 centi-seconds
BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge0" = Counter32: 1
BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge2" = Counter32: 1
BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge0" = Hex-STRING: 80 00 00 40 95 30 5E 31
BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge2" = Hex-STRING: 80 00 00 50 8B B8 C6 A9</screen>
<para>To change the bridge interface being monitored via the
<literal>mib-2.dot1dBridge</literal> subtree do:</para>
<screen>&prompt.user; <userinput>snmpset -v 2c -c private bridge1.example.com</userinput>
BEGEMOT-BRIDGE-MIB::begemotBridgeDefaultBridgeIf.0 s bridge2</screen>
</sect3>
</sect2>
</sect1>
<sect1 id="network-aggregation">
<sect1info>
<authorgroup>
<author>
<firstname>Andrew</firstname>
<surname>Thompson</surname>
<contrib>Written by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Link Aggregation and Failover</title>
<indexterm><primary>lagg</primary></indexterm>
<indexterm><primary>failover</primary></indexterm>
<indexterm><primary>fec</primary></indexterm>
<indexterm><primary>lacp</primary></indexterm>
<indexterm><primary>loadbalance</primary></indexterm>
<indexterm><primary>roundrobin</primary></indexterm>
<sect2>
<title>Introduction</title>
<para>The &man.lagg.4; interface allows aggregation of multiple
network interfaces as one virtual interface for the purpose of
providing fault-tolerance and high-speed links.</para>
</sect2>
<sect2>
<title>Operating Modes</title>
<variablelist>
<varlistentry>
<term>Failover</term>
<listitem>
<para>Sends and receives traffic only through the master
port. If the master port becomes unavailable, the next
active port is used. The first interface added is the
master port; any interfaces added after that are used as
failover devices. If failover to a non-master port
occurs, the original port will become master when it
becomes available again.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>&cisco; Fast &etherchannel;</term>
<listitem>
<para>&cisco; Fast &etherchannel; (FEC), is a static setup
and does not negotiate aggregation with the peer or
exchange frames to monitor the link. If the switch
supports LACP then that should be used instead.</para>
<para><acronym>FEC</acronym> balances outgoing traffic
across the active ports based on hashed protocol header
information and accepts incoming traffic from any active
port. The hash includes the Ethernet source and
destination address, and, if available, the VLAN tag,
and the IPv4/IPv6 source and destination address.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>LACP</term>
<listitem>
<para>The &ieee; 802.3ad Link Aggregation Control Protocol
(LACP) and the Marker Protocol. LACP will negotiate a
set of aggregable links with the peer in to one or more
Link Aggregated Groups (LAG). Each LAG is composed of
ports of the same speed, set to full-duplex operation.
The traffic will be balanced across the ports in the LAG
with the greatest total speed, in most cases there will
only be one LAG which contains all ports. In the event
of changes in physical connectivity, Link Aggregation
will quickly converge to a new configuration.</para>
<para><acronym>LACP</acronym> balances outgoing traffic
across the active ports based on hashed protocol header
information and accepts incoming traffic from any active
port. The hash includes the Ethernet source and
destination address, and, if available, the VLAN tag,
and the IPv4/IPv6 source and destination address.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Loadbalance</term>
<listitem>
<para>This is an alias of <emphasis>FEC</emphasis>
mode.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Round-robin</term>
<listitem>
<para>Distributes outgoing traffic using a round-robin
scheduler through all active ports and accepts incoming
traffic from any active port. This mode violates
Ethernet Frame ordering and should be used with
caution.</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2>
<title>Examples</title>
<example id="networking-lacp-aggregation-cisco">
<title>LACP Aggregation with a &cisco; Switch</title>
<para>This example connects two interfaces on a &os; machine
to the switch as a single load balanced and fault tolerant
link. More interfaces can be added to increase throughput
and fault tolerance. Since frame ordering is mandatory on
Ethernet links then any traffic between two stations always
flows over the same physical link limiting the maximum speed
to that of one interface. The transmit algorithm attempts
to use as much information as it can to distinguish
different traffic flows and balance across the available
interfaces.</para>
<para>On the &cisco; switch add the
<replaceable>FastEthernet0/1</replaceable> and
<replaceable>FastEthernet0/2</replaceable> interfaces to the
channel-group <replaceable>1</replaceable>:</para>
<screen><userinput>interface <replaceable>FastEthernet0/1</replaceable>
channel-group <replaceable>1</replaceable> mode active
channel-protocol lacp</userinput>
!
<userinput>interface <replaceable>FastEthernet0/2</replaceable>
channel-group <replaceable>1</replaceable> mode active
channel-protocol lacp</userinput></screen>
<para>Create the &man.lagg.4; interface using
<replaceable>fxp0</replaceable> and
<replaceable>fxp1</replaceable>, and bring the interfaces up
with the IP Address of
<replaceable>10.0.0.3/24</replaceable>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>fxp0</replaceable> up</userinput>
&prompt.root; <userinput>ifconfig <replaceable>fxp1</replaceable> up</userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> create </userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> up laggproto lacp laggport <replaceable>fxp0</replaceable> laggport <replaceable>fxp1</replaceable> <replaceable>10.0.0.3/24</replaceable></userinput></screen>
<para>View the interface status by running:</para>
<screen>&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal></userinput></screen>
<para>Ports marked as <emphasis>ACTIVE</emphasis> are part of
the active aggregation group that has been negotiated with
the remote switch and traffic will be transmitted and
received. Use the verbose output of &man.ifconfig.8; to
view the LAG identifiers.</para>
<screen>lagg0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
options=8&lt;VLAN_MTU&gt;
ether 00:05:5d:71:8d:b8
media: Ethernet autoselect
status: active
laggproto lacp
laggport: fxp1 flags=1c&lt;ACTIVE,COLLECTING,DISTRIBUTING&gt;
laggport: fxp0 flags=1c&lt;ACTIVE,COLLECTING,DISTRIBUTING&gt;</screen>
<para>To see the port status on the switch, use
<userinput>show lacp neighbor</userinput>:</para>
<screen>switch# show lacp neighbor
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode
Channel group 1 neighbors
Partner's information:
LACP port Oper Port Port
Port Flags Priority Dev ID Age Key Number State
Fa0/1 SA 32768 0005.5d71.8db8 29s 0x146 0x3 0x3D
Fa0/2 SA 32768 0005.5d71.8db8 29s 0x146 0x4 0x3D</screen>
<para>For more detail use the <userinput>show lacp neighbor
detail</userinput> command.</para>
<para>To retain this configuration across reboots, the
following entries can be added to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_<replaceable>fxp0</replaceable>="up"
ifconfig_<replaceable>fxp1</replaceable>="up"
cloned_interfaces="<literal>lagg<replaceable>0</replaceable></literal>"
ifconfig_<literal>lagg<replaceable>0</replaceable></literal>="laggproto lacp laggport <replaceable>fxp0</replaceable> laggport <replaceable>fxp1</replaceable> <replaceable>10.0.0.3/24</replaceable>"</programlisting>
</example>
<example id="networking-lagg-failover">
<title>Failover Mode</title>
<para>Failover mode can be used to switch over to a secondary
interface if the link is lost on the master interface.
Bring the underlying physical interfaces up. Create the
&man.lagg.4; interface, using
<replaceable>fxp0</replaceable> as the master interface and
<replaceable>fxp1</replaceable> as the secondary interface
and assign an IP Address of
<replaceable>10.0.0.15/24</replaceable>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>fxp0</replaceable> up</userinput>
&prompt.root; <userinput>ifconfig <replaceable>fxp1</replaceable> up</userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> create</userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> up laggproto failover laggport <replaceable>fxp0</replaceable> laggport <replaceable>fxp1</replaceable> <replaceable>10.0.0.15/24</replaceable></userinput></screen>
<para>The interface will look something like this, the major
differences will be the <acronym>MAC</acronym> address and
the device names:</para>
<screen>&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal></userinput>
lagg0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
options=8&lt;VLAN_MTU&gt;
ether 00:05:5d:71:8d:b8
inet 10.0.0.15 netmask 0xffffff00 broadcast 10.0.0.255
media: Ethernet autoselect
status: active
laggproto failover
laggport: fxp1 flags=0&lt;&gt;
laggport: fxp0 flags=5&lt;MASTER,ACTIVE&gt;</screen>
<para>Traffic will be transmitted and received on
<replaceable>fxp0</replaceable>. If the link is lost on
<replaceable>fxp0</replaceable> then
<replaceable>fxp1</replaceable> will become the active link.
If the link is restored on the master interface then it will
once again become the active link.</para>
<para>To retain this configuration across reboots, the
following entries can be added to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_<replaceable>fxp0</replaceable>="up"
ifconfig_<replaceable>fxp1</replaceable>="up"
cloned_interfaces="<literal>lagg<replaceable>0</replaceable></literal>"
ifconfig_<literal>lagg<replaceable>0</replaceable></literal>="laggproto failover laggport <replaceable>fxp0</replaceable> laggport <replaceable>fxp1</replaceable> <replaceable>10.0.0.15/24</replaceable>"</programlisting>
</example>
<example id="networking-lagg-wired-and-wireless">
<title>Failover Mode Between Wired and Wireless
Interfaces</title>
<para>For laptop users, it is usually desirable to make
wireless as a secondary interface, which is to be used when
the wired connection is not available. With &man.lagg.4;,
it is possible to use one IP address, prefer the wired
connection for both performance and security reasons, while
maintaining the ability to transfer data over the wireless
connection.</para>
<para>In this setup, we will need to override the underlying
wireless interface's <acronym>MAC</acronym> address to match
the &man.lagg.4;'s, which is inherited from the master
interface being used, the wired interface.</para>
<para>In this setup, we will treat the wired interface,
<replaceable>bge0</replaceable>, as the master, and the
wireless interface, <replaceable>wlan0</replaceable>, as the
failover interface. The <replaceable>wlan0</replaceable>
was created from <replaceable>iwn0</replaceable> which we
will set up with the wired connection's
<acronym>MAC</acronym> address. The first step would be to
obtain the <acronym>MAC</acronym> address from the wired
interface:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>bge0</replaceable></userinput>
bge0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
options=19b&lt;RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4&gt;
ether 00:21:70:da:ae:37
inet6 fe80::221:70ff:feda:ae37%bge0 prefixlen 64 scopeid 0x2
nd6 options=29&lt;PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL&gt;
media: Ethernet autoselect (1000baseT &lt;full-duplex&gt;)
status: active</screen>
<para>You can replace the <replaceable>bge0</replaceable> to
match your reality, and will get a different
<literal>ether</literal> line which is the
<acronym>MAC</acronym> address of your wired interface.
Now, we change the underlying wireless interface,
<replaceable>iwn0</replaceable>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>iwn0</replaceable> ether <replaceable>00:21:70:da:ae:37</replaceable></userinput></screen>
<para>Bring up the wireless interface but don't set up any IP
address on it:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>wlan0</replaceable> create wlandev <replaceable>iwn0</replaceable> ssid <replaceable>my_router</replaceable> up</userinput></screen>
<para>Bring the <replaceable>bge0</replaceable> interface up.
Create the &man.lagg.4; interface with
<replaceable>bge0</replaceable> as master, and failover to
<replaceable>wlan0</replaceable> if necessary:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>bge0</replaceable> up</userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> create</userinput>
&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal> up laggproto failover laggport <replaceable>bge0</replaceable> laggport <replaceable>wlan0</replaceable></userinput></screen>
<para>The interface will look something like this, the major
differences will be the <acronym>MAC</acronym> address and
the device names:</para>
<screen>&prompt.root; <userinput>ifconfig <literal>lagg<replaceable>0</replaceable></literal></userinput>
lagg0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; metric 0 mtu 1500
options=8&lt;VLAN_MTU&gt;
ether 00:21:70:da:ae:37
media: Ethernet autoselect
status: active
laggproto failover
laggport: wlan0 flags=0&lt;&gt;
laggport: bge0 flags=5&lt;MASTER,ACTIVE&gt;</screen>
<para>Then start the DHCP client to obtain an IP
address:</para>
<screen>&prompt.root; <userinput>dhclient <literal>lagg<replaceable>0</replaceable></literal></userinput></screen>
<para>To retain this configuration across reboots, the
following entries can be added to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_bge0="up"
ifconfig_iwn0="ether 00:21:70:da:ae:37"
wlans_iwn0="wlan0"
ifconfig_wlan0="WPA"
cloned_interfaces="<literal>lagg<replaceable>0</replaceable></literal>"
ifconfig_<literal>lagg<replaceable>0</replaceable></literal>="laggproto failover laggport bge0 laggport wlan0 DHCP"</programlisting>
</example>
</sect2>
</sect1>
<sect1 id="network-diskless">
<sect1info>
<authorgroup>
<author>
<firstname>Jean-Fran&ccedil;ois</firstname>
<surname>Dock&egrave;s</surname>
<contrib>Updated by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Alex</firstname>
<surname>Dupre</surname>
<contrib>Reorganized and enhanced by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Diskless Operation</title>
<indexterm><primary>diskless workstation</primary></indexterm>
<indexterm><primary>diskless operation</primary></indexterm>
<para>A FreeBSD machine can boot over the network and operate
without a local disk, using file systems mounted from an
<acronym>NFS</acronym> server. No system modification is
necessary, beyond standard configuration files. Such a system
is relatively easy to set up because all the necessary elements
are readily available:</para>
<itemizedlist>
<listitem>
<para>There are at least two possible methods to load the
kernel over the network:</para>
<itemizedlist>
<listitem>
<para><acronym>PXE</acronym>: The &intel; Preboot
eXecution Environment system is a form of smart boot ROM
built into some networking cards or motherboards. See
&man.pxeboot.8; for more details.</para>
</listitem>
<listitem>
<para>The <application>Etherboot</application> port
(<filename role="package">net/etherboot</filename>)
produces ROM-able code to boot kernels over the network.
The code can be either burnt into a boot PROM on a
network card, or loaded from a local floppy (or hard)
disk drive, or from a running &ms-dos; system. Many
network cards are supported.</para>
</listitem>
</itemizedlist>
</listitem>
<listitem>
<para>A sample script
(<filename>/usr/share/examples/diskless/clone_root</filename>)
eases the creation and maintenance of the workstation's root
file system on the server. The script will probably require
a little customization but it will get you started very
quickly.</para>
</listitem>
<listitem>
<para>Standard system startup files exist in
<filename>/etc</filename> to detect and support a diskless
system startup.</para>
</listitem>
<listitem>
<para>Swapping, if needed, can be done either to an
<acronym>NFS</acronym> file or to a local disk.</para>
</listitem>
</itemizedlist>
<para>There are many ways to set up diskless workstations. Many
elements are involved, and most can be customized to suit local
taste. The following will describe variations on the setup of a
complete system, emphasizing simplicity and compatibility with
the standard FreeBSD startup scripts. The system described has
the following characteristics:</para>
<itemizedlist>
<listitem>
<para>The diskless workstations use a shared read-only
<filename>/</filename> file system, and a shared
read-only <filename>/usr</filename>.</para>
<para>The root file system is a copy of a standard FreeBSD
root (typically the server's), with some configuration files
overridden by ones specific to diskless operation or,
possibly, to the workstation they belong to.</para>
<para>The parts of the root which have to be writable are
overlaid with &man.md.4; file systems. Any changes will be
lost when the system reboots.</para>
</listitem>
<listitem>
<para>The kernel is transferred and loaded either with
<application>Etherboot</application> or
<acronym>PXE</acronym> as some situations may mandate the
use of either method.</para>
</listitem>
</itemizedlist>
<caution>
<para>As described, this system is insecure. It should live in
a protected area of a network, and be untrusted by other
hosts.</para>
</caution>
<para>All the information in this section has been tested using
&os; 5.2.1-RELEASE.</para>
<sect2>
<title>Background Information</title>
<para>Setting up diskless workstations is both relatively
straightforward and prone to errors. These are sometimes
difficult to diagnose for a number of reasons. For
example:</para>
<itemizedlist>
<listitem>
<para>Compile time options may determine different behaviors
at runtime.</para>
</listitem>
<listitem>
<para>Error messages are often cryptic or totally
absent.</para>
</listitem>
</itemizedlist>
<para>In this context, having some knowledge of the background
mechanisms involved is very useful to solve the problems that
may arise.</para>
<para>Several operations need to be performed for a successful
bootstrap:</para>
<itemizedlist>
<listitem>
<para>The machine needs to obtain initial parameters such as
its IP address, executable filename, server name, root
path. This is done using the <acronym>DHCP</acronym> or
BOOTP protocols. <acronym>DHCP</acronym> is a compatible
extension of BOOTP, and uses the same port numbers and
basic packet format.</para>
<para>It is possible to configure a system to use only
BOOTP. The &man.bootpd.8; server program is included in
the base &os; system.</para>
<para>However, <acronym>DHCP</acronym> has a number of
advantages over BOOTP (nicer configuration files,
possibility of using <acronym>PXE</acronym>, plus many
others not directly related to diskless operation), and we
will describe mainly a <acronym>DHCP</acronym>
configuration, with equivalent examples using
&man.bootpd.8; when possible. The sample configuration
will use the <application>ISC DHCP</application> software
package (release 3.0.1.r12 was installed on the test
server).</para>
</listitem>
<listitem>
<para>The machine needs to transfer one or several programs
to local memory. Either <acronym>TFTP</acronym> or
<acronym>NFS</acronym> are used. The choice between
<acronym>TFTP</acronym> and <acronym>NFS</acronym> is a
compile time option in several places. A common source of
error is to specify filenames for the wrong protocol:
<acronym>TFTP</acronym> typically transfers all files from
a single directory on the server, and would expect
filenames relative to this directory.
<acronym>NFS</acronym> needs absolute file paths.</para>
</listitem>
<listitem>
<para>The possible intermediate bootstrap programs and the
kernel need to be initialized and executed. There are
several important variations in this area:</para>
<itemizedlist>
<listitem>
<para><acronym>PXE</acronym> will load &man.pxeboot.8;,
which is a modified version of the &os; third stage
loader. The &man.loader.8; will obtain most
parameters necessary to system startup, and leave them
in the kernel environment before transferring control.
It is possible to use a <filename>GENERIC</filename>
kernel in this case.</para>
</listitem>
<listitem>
<para><application>Etherboot</application>, will
directly load the kernel, with less preparation. You
will need to build a kernel with specific
options.</para>
</listitem>
</itemizedlist>
<para><acronym>PXE</acronym> and
<application>Etherboot</application> work equally well;
however, because kernels normally let the &man.loader.8;
do more work for them, <acronym>PXE</acronym> is the
preferred method.</para>
<para>If your <acronym>BIOS</acronym> and network cards
support <acronym>PXE</acronym>, you should probably use
it.</para>
</listitem>
<listitem>
<para>Finally, the machine needs to access its file systems.
<acronym>NFS</acronym> is used in all cases.</para>
</listitem>
</itemizedlist>
<para>See also &man.diskless.8; manual page.</para>
</sect2>
<sect2>
<title>Setup Instructions</title>
<sect3>
<title>Configuration Using <application>ISC
DHCP</application></title>
<indexterm>
<primary>DHCP</primary>
<secondary>diskless operation</secondary>
</indexterm>
<para>The <application>ISC DHCP</application> server can
answer both BOOTP and <acronym>DHCP</acronym>
requests.</para>
<para><application>ISC DHCP 4.2</application> is not part of
the base system. You will first need to install the
<filename role="package">net/isc-dhcp42-server</filename>
port or the corresponding package.</para>
<para>Once <application>ISC DHCP</application> is installed,
it needs a configuration file to run (normally named
<filename>/usr/local/etc/dhcpd.conf</filename>). Here
follows a commented example, where host
<hostid>margaux</hostid> uses
<application>Etherboot</application> and host
<hostid>corbieres</hostid> uses
<acronym>PXE</acronym>:</para>
<programlisting>default-lease-time 600;
max-lease-time 7200;
authoritative;
option domain-name "example.com";
option domain-name-servers 192.168.4.1;
option routers 192.168.4.1;
subnet 192.168.4.0 netmask 255.255.255.0 {
use-host-decl-names on; <co id="co-dhcp-host-name">
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.4.255;
host margaux {
hardware ethernet 01:23:45:67:89:ab;
fixed-address margaux.example.com;
next-server 192.168.4.4; <co id="co-dhcp-next-server">
filename "/data/misc/kernel.diskless"; <co id="co-dhcp-filename">
option root-path "192.168.4.4:/data/misc/diskless"; <co id="co-dhcp-root-path">
}
host corbieres {
hardware ethernet 00:02:b3:27:62:df;
fixed-address corbieres.example.com;
next-server 192.168.4.4;
filename "pxeboot";
option root-path "192.168.4.4:/data/misc/diskless";
}
}</programlisting>
<calloutlist>
<callout arearefs="co-dhcp-host-name">
<para>This option tells <application>dhcpd</application>
to send the value in the <literal>host</literal>
declarations as the hostname for the diskless host.
An alternate way would be to add an <literal>option
host-name
<replaceable>margaux</replaceable></literal> inside
the <literal>host</literal> declarations.</para>
</callout>
<callout arearefs="co-dhcp-next-server">
<para>The <literal>next-server</literal> directive
designates the <acronym>TFTP</acronym> or
<acronym>NFS</acronym> server to use for loading
loader or kernel file (the default is to use the same
host as the <acronym>DHCP</acronym> server).</para>
</callout>
<callout arearefs="co-dhcp-filename">
<para>The <literal>filename</literal> directive
defines the file that
<application>Etherboot</application> or
<acronym>PXE</acronym> will load for the next execution
step. It must be specified according to the transfer
method used. <application>Etherboot</application> can
be compiled to use <acronym>NFS</acronym> or
<acronym>TFTP</acronym>. The &os; port configures
<acronym>NFS</acronym> by default.
<acronym>PXE</acronym> uses <acronym>TFTP</acronym>,
which is why a relative filename is used here (this may
depend on the <acronym>TFTP</acronym> server
configuration, but would be fairly typical). Also,
<acronym>PXE</acronym> loads
<filename>pxeboot</filename>, not the kernel. There are
other interesting possibilities, like loading
<filename>pxeboot</filename> from a &os; CD-ROM
<filename class="directory">/boot</filename> directory
(as &man.pxeboot.8; can load a
<filename>GENERIC</filename> kernel, this makes it
possible to use <acronym>PXE</acronym> to boot from a
remote CD-ROM).</para>
</callout>
<callout arearefs="co-dhcp-root-path">
<para>The <literal>root-path</literal> option defines
the path to the root file system, in usual
<acronym>NFS</acronym> notation. When using
<acronym>PXE</acronym>, it is possible to leave off the
host's IP as long as you do not enable the kernel option
BOOTP. The <acronym>NFS</acronym> server will then be
the same as the <acronym>TFTP</acronym> one.</para>
</callout>
</calloutlist>
</sect3>
<sect3>
<title>Configuration Using BOOTP</title>
<indexterm>
<primary>BOOTP</primary>
<secondary>diskless operation</secondary>
</indexterm>
<para>Here follows an equivalent
<application>bootpd</application> configuration (reduced to
one client). This would be found in
<filename>/etc/bootptab</filename>.</para>
<para>Please note that <application>Etherboot</application>
must be compiled with the non-default option
<literal>NO_DHCP_SUPPORT</literal> in order to use BOOTP,
and that <acronym>PXE</acronym> <emphasis>needs</emphasis>
<acronym>DHCP</acronym>. The only obvious advantage of
<application>bootpd</application> is that it exists in the
base system.</para>
<programlisting>.def100:\
:hn:ht=1:sa=192.168.4.4:vm=rfc1048:\
:sm=255.255.255.0:\
:ds=192.168.4.1:\
:gw=192.168.4.1:\
:hd="/tftpboot":\
:bf="/kernel.diskless":\
:rp="192.168.4.4:/data/misc/diskless":
margaux:ha=0123456789ab:tc=.def100</programlisting>
</sect3>
<sect3>
<title>Preparing a Boot Program with
<application>Etherboot</application></title>
<indexterm>
<primary>Etherboot</primary>
</indexterm>
<para><ulink
url="http://etherboot.sourceforge.net">Etherboot's Web
site</ulink> contains <ulink
url="http://etherboot.sourceforge.net/doc/html/userman/t1.html">
extensive documentation</ulink> mainly intended for Linux
systems, but nonetheless containing useful information. The
following will just outline how you would use
<application>Etherboot</application> on a FreeBSD
system.</para>
<para>You must first install the
<filename role="package">net/etherboot</filename> package or
port.</para>
<para>You can change the <application>Etherboot</application>
configuration (i.e., to use <acronym>TFTP</acronym> instead
of <acronym>NFS</acronym>) by editing the
<filename>Config</filename> file in the
<application>Etherboot</application> source
directory.</para>
<para>For our setup, we shall use a boot floppy. For other
methods (PROM, or &ms-dos; program), please refer to the
<application>Etherboot</application> documentation.</para>
<para>To make a boot floppy, insert a floppy in the drive on
the machine where you installed
<application>Etherboot</application>, then change your
current directory to the <filename>src</filename> directory
in the <application>Etherboot</application> tree and
type:</para>
<screen>&prompt.root; <userinput>gmake bin32/<replaceable>devicetype</replaceable>.fd0</userinput></screen>
<para><replaceable>devicetype</replaceable> depends on the
type of the Ethernet card in the diskless workstation.
Refer to the <filename>NIC</filename> file in the same
directory to determine the right
<replaceable>devicetype</replaceable>.</para>
</sect3>
<sect3>
<title>Booting with <acronym>PXE</acronym></title>
<para>By default, the &man.pxeboot.8; loader loads the kernel
via <acronym>NFS</acronym>. It can be compiled to use
<acronym>TFTP</acronym> instead by specifying the
<literal>LOADER_TFTP_SUPPORT</literal> option in
<filename>/etc/make.conf</filename>. See the comments in
<filename>/usr/share/examples/etc/make.conf</filename> for
instructions.</para>
<para>There are two other <filename>make.conf</filename>
options which may be useful for setting up a serial console
diskless machine:
<literal>BOOT_PXELDR_PROBE_KEYBOARD</literal>, and
<literal>BOOT_PXELDR_ALWAYS_SERIAL</literal>.</para>
<para>To use <acronym>PXE</acronym> when the machine starts,
you will usually need to select the <literal>Boot from
network</literal> option in your <acronym>BIOS</acronym>
setup, or type a function key during the PC
initialization.</para>
</sect3>
<sect3>
<title>Configuring the <acronym>TFTP</acronym> and
<acronym>NFS</acronym> Servers</title>
<indexterm>
<primary>TFTP</primary>
<secondary>diskless operation</secondary>
</indexterm>
<indexterm>
<primary>NFS</primary>
<secondary>diskless operation</secondary>
</indexterm>
<para>If you are using <acronym>PXE</acronym> or
<application>Etherboot</application> configured to use
<acronym>TFTP</acronym>, you need to enable
<application>tftpd</application> on the file server:</para>
<procedure>
<step>
<para>Create a directory from which
<application>tftpd</application> will serve the files,
e.g., <filename>/tftpboot</filename>.</para>
</step>
<step>
<para>Add this line to your
<filename>/etc/inetd.conf</filename>:</para>
<programlisting>tftp dgram udp wait root /usr/libexec/tftpd tftpd -l -s /tftpboot</programlisting>
<note>
<para>It appears that at least some
<acronym>PXE</acronym> versions want the
<acronym>TCP</acronym> version of
<acronym>TFTP</acronym>. In this case, add a second
line, replacing <literal>dgram udp</literal> with
<literal>stream tcp</literal>.</para>
</note>
</step>
<step>
<para>Tell <application>inetd</application> to reread its
configuration file. The
<option>inetd_enable="YES"</option> must be in the
<filename>/etc/rc.conf</filename> file for this command
to execute correctly:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/inetd restart</userinput></screen>
</step>
</procedure>
<para>You can place the <filename>tftpboot</filename>
directory anywhere on the server. Make sure that the
location is set in both <filename>inetd.conf</filename> and
<filename>dhcpd.conf</filename>.</para>
<para>In all cases, you also need to enable
<acronym>NFS</acronym> and export the appropriate file
system on the <acronym>NFS</acronym> server.</para>
<procedure>
<step>
<para>Add this to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>nfs_server_enable="YES"</programlisting>
</step>
<step>
<para>Export the file system where the diskless root
directory is located by adding the following to
<filename>/etc/exports</filename> (adjust the volume
mount point and replace <replaceable>margaux
corbieres</replaceable> with the names of the diskless
workstations):</para>
<programlisting><replaceable>/data/misc</replaceable> -alldirs -ro <replaceable>margaux corbieres</replaceable></programlisting>
</step>
<step>
<para>Tell <application>mountd</application> to reread its
configuration file. If you actually needed to enable
<acronym>NFS</acronym> in
<filename>/etc/rc.conf</filename> at the first step, you
probably want to reboot instead.</para>
<screen>&prompt.root; <userinput>/etc/rc.d/mountd restart</userinput></screen>
</step>
</procedure>
</sect3>
<sect3>
<title>Building a Diskless Kernel</title>
<indexterm>
<primary>diskless operation</primary>
<secondary>kernel configuration</secondary>
</indexterm>
<para>If using <application>Etherboot</application>, you need
to create a kernel configuration file for the diskless
client with the following options (in addition to the usual
ones):</para>
<programlisting>options BOOTP # Use BOOTP to obtain IP address/hostname
options BOOTP_NFSROOT # NFS mount root file system using BOOTP info</programlisting>
<para>You may also want to use <literal>BOOTP_NFSV3</literal>,
<literal>BOOT_COMPAT</literal> and
<literal>BOOTP_WIRED_TO</literal> (refer to
<filename>NOTES</filename>).</para>
<para>These option names are historical and slightly
misleading as they actually enable indifferent use of
<acronym>DHCP</acronym> and BOOTP inside the kernel (it is
also possible to force strict BOOTP or
<acronym>DHCP</acronym> use).</para>
<para>Build the kernel (see <xref linkend="kernelconfig">),
and copy it to the place specified in
<filename>dhcpd.conf</filename>.</para>
<note>
<para>When using <acronym>PXE</acronym>, building a kernel
with the above options is not strictly necessary (though
suggested). Enabling them will cause more
<acronym>DHCP</acronym> requests to be issued during
kernel startup, with a small risk of inconsistency between
the new values and those retrieved by &man.pxeboot.8; in
some special cases. The advantage of using them is that
the host name will be set as a side effect. Otherwise you
will need to set the host name by another method, for
example in a client-specific <filename>rc.conf</filename>
file.</para>
</note>
<note>
<para>In order to be loadable with
<application>Etherboot</application>, a kernel needs to
have the device hints compiled in. You would typically
set the following option in the configuration file (see
the <filename>NOTES</filename> configuration comments
file):</para>
<programlisting>hints "GENERIC.hints"</programlisting>
</note>
</sect3>
<sect3>
<title>Preparing the Root Filesystem</title>
<indexterm>
<primary>root file system</primary>
<secondary>diskless operation</secondary>
</indexterm>
<para>You need to create a root file system for the diskless
workstations, in the location listed as
<literal>root-path</literal> in
<filename>dhcpd.conf</filename>.</para>
<sect4>
<title>Using <command>make world</command> to Populate
Root</title>
<para>This method is quick and will install a complete
virgin system (not only the root file system) into
<envar>DESTDIR</envar>. All you have to do is simply
execute the following script:</para>
<programlisting>#!/bin/sh
export DESTDIR=/data/misc/diskless
mkdir -p ${DESTDIR}
cd /usr/src; make buildworld &amp;&amp; make buildkernel
make installworld &amp;&amp; make installkernel
cd /usr/src/etc; make distribution</programlisting>
<para>Once done, you may need to customize your
<filename>/etc/rc.conf</filename> and
<filename>/etc/fstab</filename> placed into
<envar>DESTDIR</envar> according to your needs.</para>
</sect4>
</sect3>
<sect3>
<title>Configuring Swap</title>
<para>If needed, a swap file located on the server can be
accessed via <acronym>NFS</acronym>.</para>
<sect4>
<title><acronym>NFS</acronym> Swap</title>
<para>The kernel does not support enabling
<acronym>NFS</acronym> swap at boot time. Swap must be
enabled by the startup scripts, by mounting a writable
file system and creating and enabling a swap file. To
create a swap file of appropriate size, you can do like
this:</para>
<screen>&prompt.root; <userinput>dd if=/dev/zero of=<replaceable>/path/to/swapfile</replaceable> bs=1k count=1 oseek=<replaceable>100000</replaceable></userinput></screen>
<para>To enable it you have to add the following line to
your <filename>rc.conf</filename>:</para>
<programlisting>swapfile=<replaceable>/path/to/swapfile</replaceable></programlisting>
</sect4>
</sect3>
<sect3>
<title>Miscellaneous Issues</title>
<sect4>
<title>Running with a Read-only
<filename>/usr</filename></title>
<indexterm>
<primary>diskless operation</primary>
<secondary>/usr read-only</secondary>
</indexterm>
<para>If the diskless workstation is configured to run X,
you will have to adjust the
<application>XDM</application> configuration file, which
puts the error log on <filename>/usr</filename> by
default.</para>
</sect4>
<sect4>
<title>Using a Non-FreeBSD Server</title>
<para>When the server for the root file system is not
running FreeBSD, you will have to create the root file
system on a FreeBSD machine, then copy it to its
destination, using <command>tar</command> or
<command>cpio</command>.</para>
<para>In this situation, there are sometimes problems with
the special files in <filename>/dev</filename>, due to
differing major/minor integer sizes. A solution to this
problem is to export a directory from the non-FreeBSD
server, mount this directory onto a FreeBSD machine, and
use &man.devfs.5; to allocate device nodes transparently
for the user.</para>
</sect4>
</sect3>
</sect2>
</sect1>
<sect1 id="network-pxe-nfs">
<sect1info>
<authorgroup>
<author>
<firstname>Craig</firstname>
<surname>Rodrigues</surname>
<affiliation>
<address>rodrigc@FreeBSD.org</address>
</affiliation>
<contrib>Written by </contrib>
</author>
</authorgroup>
</sect1info>
<title>PXE Booting with an NFS Root File System</title>
<para>The &intel; Preboot eXecution Environment
(<acronym>PXE</acronym>) allows booting the operating system
over the network. <acronym>PXE</acronym> support is usually
provided in the <acronym>BIOS</acronym> of modern motherboards,
where it can be enabled in the <acronym>BIOS</acronym> settings
which enable booting from the network. A fully functioning
<acronym>PXE</acronym> setup also requires properly configured
<acronym>DHCP</acronym> and <acronym>TFTP</acronym>
servers.</para>
<para>When the host computer boots, it receives information over
<acronym>DHCP</acronym> about where to obtain the initial boot
loader via TFTP. After the host computer receives this
information, it downloads the boot loader via
<acronym>TFTP</acronym>, and then executes the boot loader.
This is documented in section 2.2.1 of the <ulink
url="http://download.intel.com/design/archives/wfm/downloads/pxespec.pdf">Preboot
Execution Environment (PXE) Specification</ulink>. In &os;,
the boot loader retrieved during the <acronym>PXE</acronym>
process is <filename>/boot/pxeboot</filename>. After
<filename>/boot/pxeboot</filename> executes, the &os; kernel is
loaded, and the rest of the &os; bootup sequence proceeds.
Refer to <xref linkend="boot"> for more information about the
&os; booting process.</para>
<sect2>
<title>Setting Up the <command>chroot</command> Environment for
the NFS Root File System</title>
<procedure>
<step>
<para>Choose a directory which will have a &os;
installation which will be NFS mountable. For example, a
directory such as
<filename>/b/tftpboot/FreeBSD/install</filename> can be
used.</para>
<screen>&prompt.root; <userinput>export NFSROOTDIR=/b/tftpboot/FreeBSD/install</userinput>
&prompt.root; <userinput>mkdir -p ${NFSROOTDIR}</userinput></screen>
</step>
<step>
<para>Enable the NFS server by following the instructions
in <xref linkend="network-configuring-nfs">.</para>
</step>
<step>
<para>Export the directory via NFS by adding the following
to <filename>/etc/exports</filename>:</para>
<programlisting>/b -ro -alldirs</programlisting>
</step>
<step>
<para>Restart the NFS server:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/nfsd restart</userinput></screen>
</step>
<step>
<para>Enable &man.inetd.8; by following the steps outlined
in <xref linkend="network-inetd-settings">.</para>
</step>
<step>
<para>Add the following line to
<filename>/etc/inetd.conf</filename>:</para>
<programlisting>tftp dgram udp wait root /usr/libexec/tftpd tftpd -l -s /b/tftpboot</programlisting>
</step>
<step>
<para>Restart inetd:</para>
<screen>&prompt.root; <userinput>/etc/rc.d/inetd restart</userinput></screen>
</step>
<step>
<para><link linkend="makeworld">Rebuild the &os; kernel and
userland</link>:</para>
<screen>&prompt.root; <userinput>cd /usr/src</userinput>
&prompt.root; <userinput>make buildworld</userinput>
&prompt.root; <userinput>make buildkernel</userinput></screen>
</step>
<step>
<para>Install &os; into the directory mounted over
<acronym>NFS</acronym>:</para>
<screen>&prompt.root; <userinput>make installworld DESTDIR=${NFSROOTDIR}</userinput>
&prompt.root; <userinput>make installkernel DESTDIR=${NFSROOTDIR}</userinput>
&prompt.root; <userinput>make distribution DESTDIR=${NFSROOTDIR}</userinput></screen>
</step>
<step>
<para>Test that the <acronym>TFTP</acronym> server works and
can download the boot loader which will be obtained
via PXE:</para>
<screen>&prompt.root; <userinput>tftp localhost</userinput>
tftp> <userinput>get FreeBSD/install/boot/pxeboot</userinput>
Received 264951 bytes in 0.1 seconds</screen>
</step>
<step>
<para>Edit <filename>${NFSROOTDIR}/etc/fstab</filename> and
create an entry to mount the root file system over
NFS:</para>
<programlisting># Device Mountpoint FSType Options Dump Pass
myhost.example.com:/b/tftpboot/FreeBSD/install / nfs ro 0 0</programlisting>
<para>Replace
<replaceable>myhost.example.com</replaceable> with the
hostname or IP address of your <acronym>NFS</acronym>
server. In this example, the root file system is mounted
"read-only" in order to prevent <acronym>NFS</acronym>
clients from potentially deleting the contents of the root
file system.</para>
</step>
<step>
<para>Set the root password in the &man.chroot.8;
environment.</para>
<screen>&prompt.root; <userinput>chroot ${NFSROOTDIR}</userinput>
&prompt.root; <userinput>passwd</userinput></screen>
<para>This will set the root password for client
machines which are <acronym>PXE</acronym>
booting.</para>
</step>
<step>
<para>Enable ssh root logins for client machines which are
<acronym>PXE</acronym> booting by editing
<filename>${NFSROOTDIR}/etc/ssh/sshd_config</filename> and
enabling the <literal>PermitRootLogin</literal> option.
This is documented in &man.sshd.config.5;.</para>
</step>
<step>
<para>Perform other customizations of the &man.chroot.8;
environment in ${NFSROOTDIR}. These customizations could
include things like adding packages with &man.pkg.add.1;,
editing the password file with &man.vipw.8;, or editing
&man.amd.conf.5; maps for automounting. For
example:</para>
<screen>&prompt.root; <userinput>chroot ${NFSROOTDIR}</userinput>
&prompt.root; <userinput>pkg_add -r bash</userinput></screen>
</step>
</procedure>
</sect2>
<sect2>
<title>Configuring Memory File Systems Used by
<filename>/etc/rc.initdiskless</filename></title>
<para>If you boot from an NFS root volume,
<filename>/etc/rc</filename> detects that you booted over NFS
and runs the <filename>/etc/rc.initdiskless</filename> script.
Read the comments in this script to understand what is going
on. We need to make <filename>/etc</filename> and
<filename>/var</filename> memory backed file systems because
these directories need to be writable, but the NFS root
directory is read-only.</para>
<screen>&prompt.root; <userinput>chroot ${NFSROOTDIR}</userinput>
&prompt.root; <userinput>mkdir -p conf/base</userinput>
&prompt.root; <userinput>tar -c -v -f conf/base/etc.cpio.gz --format cpio --gzip etc</userinput>
&prompt.root; <userinput>tar -c -v -f conf/base/var.cpio.gz --format cpio --gzip var</userinput></screen>
<para>When the system boots, memory file systems for
<filename>/etc</filename> and <filename>/var</filename> will
be created and mounted, and the contents of the
<filename>cpio.gz</filename> files will be copied into
them.</para>
</sect2>
<sect2 id="network-pxe-setting-up-dhcp">
<title>Setting up the DHCP Server</title>
<para>PXE requires a <acronym>TFTP</acronym> server and a
<acronym>DHCP</acronym> server to be set up. The
<acronym>DHCP</acronym> server does not necessarily need to be
the same machine as the <acronym>TFTP</acronym> server, but it
needs to be accessible in your network.</para>
<procedure>
<step>
<para>Install the <acronym>DHCP</acronym> server by
following the instructions documented at
<xref linkend="network-dhcp-server">. Make sure that
<filename>/etc/rc.conf</filename> and
<filename>/usr/local/etc/dhcpd.conf</filename> are
correctly configured.</para>
</step>
<step>
<para>In <filename>/usr/local/etc/dhcpd.conf</filename>,
configure the <literal>next-server</literal>,
<literal>filename</literal>, and
<literal>option root-path</literal> settings, to specify
your <acronym>TFTP</acronym> server IP address, the path
to <filename>/boot/pxeboot</filename> in
<acronym>TFTP</acronym>, and the path to the
<acronym>NFS</acronym> root file system. Here is a sample
<filename>dhcpd.conf</filename> setup:</para>
<programlisting>subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.2 192.168.0.3 ;
option subnet-mask 255.255.255.0 ;
option routers 192.168.0.1 ;
option broadcast-address 192.168.0.255 ;
option domain-name-server 192.168.35.35, 192.168.35.36 ;
option domain-name "example.com";
# IP address of TFTP server
next-server 192.168.0.1 ;
# path of boot loader obtained
# via tftp
filename "FreeBSD/install/boot/pxeboot" ;
# pxeboot boot loader will try to NFS mount this directory for root FS
option root-path "192.168.0.1:/b/tftpboot/FreeBSD/install/" ;
}</programlisting>
</step>
</procedure>
</sect2>
<sect2>
<title>Configuring the PXE Client and Debugging Connection
Problems</title>
<procedure>
<step>
<para>When the client machine boots up, enter the
<acronym>BIOS</acronym> configuration menu. Configure the
<acronym>BIOS</acronym> to boot from the network. If all
your previous configuration steps are correct, then
everything should &quot;just work&quot;.</para>
</step>
<step>
<para>Use the
<filename role="package">net/wireshark</filename> port to
debug the network traffic involved during the
<acronym>PXE</acronym> booting process, which is
illustrated in the diagram below. In
<xref linkend="network-pxe-setting-up-dhcp">, an example
configuration is shown where the <acronym>DHCP</acronym>,
<acronym>TFTP</acronym>, and <acronym>NFS</acronym>
servers are actually on the same machine. However, these
severs can be on separate machines.</para>
<figure>
<title>PXE Booting process with NFS root mount</title>
<mediaobjectco>
<imageobjectco>
<areaspec units="calspair">
<area id="co-pxenfs1" coords="2873,8133 3313,7266">
<area id="co-pxenfs2" coords="3519,6333 3885,5500">
<area id="co-pxenfs3" coords="4780,5866 5102,5200">
<area id="co-pxenfs4" coords="4794,4333 5102,3600">
<area id="co-pxenfs5" coords="3108,2666 3519,1800">
</areaspec>
<imageobject>
<imagedata fileref="advanced-networking/pxe-nfs">
</imageobject>
<calloutlist>
<callout arearefs="co-pxenfs1">
<para>Client broadcasts DHCPDISCOVER.</para>
</callout>
<callout arearefs="co-pxenfs2">
<para>DHCP server responds with IP address,
<literal>next-server</literal>,
<literal>filename</literal>, and
<literal>root-path</literal>.</para>
</callout>
<callout arearefs="co-pxenfs3">
<para>Client sends <acronym>TFTP</acronym>
request to <literal>next-server</literal>
asking to retrieve
<literal>filename</literal>.</para>
</callout>
<callout arearefs="co-pxenfs4">
<para>TFTP server responds and sends
<literal>filename</literal> to client.</para>
</callout>
<callout arearefs="co-pxenfs5">
<para>Client executes
<literal>filename</literal> which is
&man.pxeboot.8;. &man.pxeboot.8; loads the
kernel. When the kernel executes, the root
filesystem specified by
<literal>root-path</literal> is mounted over
<acronym>NFS</acronym>.</para>
</callout>
</calloutlist>
</imageobjectco>
</mediaobjectco>
</figure>
</step>
<step>
<para>Make sure that the <filename>pxeboot</filename> file
can be retrieved by <acronym>TFTP</acronym>. On your
<acronym>TFTP</acronym> server, look in
<filename>/var/log/xferlog</filename> to ensure that the
<filename>pxeboot</filename> file is being retrieved from
the correct location. To test the configuration from
<filename>dhcpd.conf</filename> above:</para>
<screen>&prompt.root; <userinput>tftp 192.168.0.1</userinput>
tftp> <userinput>get FreeBSD/install/boot/pxeboot</userinput>
Received 264951 bytes in 0.1 seconds</screen>
<para>Read &man.tftpd.8; and &man.tftp.1;. The
<literal>BUGS</literal> sections in these pages document
some limitations with <acronym>TFTP</acronym>.</para>
</step>
<step>
<para>Make sure that the root file system can be mounted
via <acronym>NFS</acronym>. To test configuration from
<filename>dhcpd.conf</filename> above:</para>
<screen>&prompt.root; <userinput>mount -t nfs 192.168.0.1:/b/tftpboot/FreeBSD/install /mnt</userinput></screen>
</step>
<step>
<para>Read the code in
<filename>src/sys/boot/i386/libi386/pxe.c</filename> to
understand how the <filename>pxeboot</filename> loader
sets variables like <literal>boot.nfsroot.server</literal>
and <literal>boot.nfsroot.path</literal>. These variables
are then used in the NFS diskless root mount code in
<filename>src/sys/nfsclient/nfs_diskless.c</filename>.</para>
</step>
<step>
<para>Read &man.pxeboot.8; and &man.loader.8;.</para>
</step>
</procedure>
</sect2>
</sect1>
<sect1 id="network-isdn">
<title>ISDN</title>
<indexterm>
<primary>ISDN</primary>
</indexterm>
<para>A good resource for information on ISDN technology and
hardware is
<ulink url="http://www.alumni.caltech.edu/~dank/isdn/">Dan
Kegel's ISDN Page</ulink>.</para>
<para>A quick simple road map to ISDN follows:</para>
<itemizedlist>
<listitem>
<para>If you live in Europe you might want to investigate the
ISDN card section.</para>
</listitem>
<listitem>
<para>If you are planning to use ISDN primarily to connect to
the Internet with an Internet Provider on a dial-up
non-dedicated basis, you might look into Terminal Adapters.
This will give you the most flexibility, with the fewest
problems, if you change providers.</para>
</listitem>
<listitem>
<para>If you are connecting two LANs together, or connecting
to the Internet with a dedicated ISDN connection, you might
consider the stand alone router/bridge option.</para>
</listitem>
</itemizedlist>
<para>Cost is a significant factor in determining what solution
you will choose. The following options are listed from least
expensive to most expensive.</para>
<sect2 id="network-isdn-cards">
<sect2info>
<authorgroup>
<author>
<firstname>Hellmuth</firstname>
<surname>Michaelis</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect2info>
<title>ISDN Cards</title>
<indexterm>
<primary>ISDN</primary>
<secondary>cards</secondary>
</indexterm>
<para>FreeBSD's ISDN implementation supports only the DSS1/Q.931
(or Euro-ISDN) standard using passive cards. Some active
cards are supported where the firmware also supports other
signaling protocols; this also includes the first supported
Primary Rate (PRI) ISDN card.</para>
<para>The <application>isdn4bsd</application> software allows
you to connect to other ISDN routers using either IP over raw
HDLC or by using synchronous PPP: either by using kernel PPP
with <literal>isppp</literal>, a modified &man.sppp.4; driver,
or by using userland &man.ppp.8;. By using userland
&man.ppp.8;, channel bonding of two or more ISDN B-channels is
possible. A telephone answering machine application is also
available as well as many utilities such as a software 300
Baud modem.</para>
<para>Some growing number of PC ISDN cards are supported under
FreeBSD and the reports show that it is successfully used all
over Europe and in many other parts of the world.</para>
<para>The passive ISDN cards supported are mostly the ones with
the Infineon (formerly Siemens) ISAC/HSCX/IPAC ISDN chipsets,
but also ISDN cards with chips from Cologne Chip (ISA bus
only), PCI cards with Winbond W6692 chips, some cards with the
Tiger300/320/ISAC chipset combinations and some vendor
specific chipset based cards such as the AVM Fritz!Card PCI
V.1.0 and the AVM Fritz!Card PnP.</para>
<para>Currently the active supported ISDN cards are the AVM B1
(ISA and PCI) BRI cards and the AVM T1 PCI PRI cards.</para>
<para>For documentation on <application>isdn4bsd</application>,
have a look at the
<ulink url="http://www.freebsd-support.de/i4b/">homepage of
isdn4bsd</ulink> which also has pointers to hints, erratas
and much more documentation such as the <ulink
url="http://people.FreeBSD.org/~hm/">isdn4bsd
handbook</ulink>.</para>
<para>In case you are interested in adding support for a
different ISDN protocol, a currently unsupported ISDN PC card
or otherwise enhancing <application>isdn4bsd</application>,
please get in touch with &a.hm;.</para>
<para>For questions regarding the installation, configuration
and troubleshooting <application>isdn4bsd</application>, a
&a.isdn.name; mailing list is available.</para>
</sect2>
<sect2>
<title>ISDN Terminal Adapters</title>
<para>Terminal adapters (TA), are to ISDN what modems are to
regular phone lines.</para>
<indexterm><primary>modem</primary></indexterm>
<para>Most TA's use the standard Hayes modem AT command set, and
can be used as a drop in replacement for a modem.</para>
<para>A TA will operate basically the same as a modem except
connection and throughput speeds will be much faster than your
old modem. You will need to configure
<link linkend="ppp">PPP</link> exactly the same as for a modem
setup. Make sure you set your serial speed as high as
possible.</para>
<indexterm><primary>PPP</primary></indexterm>
<para>The main advantage of using a TA to connect to an Internet
Provider is that you can do Dynamic PPP. As IP address space
becomes more and more scarce, most providers are not willing
to provide you with a static IP anymore. Most stand-alone
routers are not able to accommodate dynamic IP
allocation.</para>
<para>TA's completely rely on the PPP daemon that you are
running for their features and stability of connection. This
allows you to upgrade easily from using a modem to ISDN on a
FreeBSD machine, if you already have PPP set up. However, at
the same time any problems you experienced with the PPP
program and are going to persist.</para>
<para>If you want maximum stability, use the kernel
<link linkend="ppp">PPP</link> option, not the
<link linkend="userppp">userland PPP</link>.</para>
<para>The following TA's are known to work with FreeBSD:</para>
<itemizedlist>
<listitem>
<para>Motorola BitSurfer and Bitsurfer Pro</para>
</listitem>
<listitem>
<para>Adtran</para>
</listitem>
</itemizedlist>
<para>Most other TA's will probably work as well, TA vendors try
to make sure their product can accept most of the standard
modem AT command set.</para>
<para>The real problem with external TA's is that, like modems,
you need a good serial card in your computer.</para>
<para>You should read the <ulink
url="&url.articles.serial-uart;/index.html">FreeBSD Serial
Hardware</ulink> tutorial for a detailed understanding of
serial devices, and the differences between asynchronous and
synchronous serial ports.</para>
<para>A TA running off a standard PC serial port (asynchronous)
limits you to 115.2&nbsp;Kbs, even though you have a
128&nbsp;Kbs connection. To fully utilize the 128&nbsp;Kbs
that ISDN is capable of, you must move the TA to a synchronous
serial card.</para>
<para>Do not be fooled into buying an internal TA and thinking
you have avoided the synchronous/asynchronous issue. Internal
TA's simply have a standard PC serial port chip built into
them. All this will do is save you having to buy another
serial cable and find another empty electrical socket.</para>
<para>A synchronous card with a TA is at least as fast as a
stand-alone router, and with a simple 386 FreeBSD box driving
it, probably more flexible.</para>
<para>The choice of synchronous card/TA v.s. stand-alone router
is largely a religious issue. There has been some discussion
of this in the mailing lists. We suggest you search the
<ulink url="&url.base;/search/index.html">archives</ulink> for
the complete discussion.</para>
</sect2>
<sect2>
<title>Stand-alone ISDN Bridges/Routers</title>
<indexterm>
<primary>ISDN</primary>
<secondary>stand-alone bridges/routers</secondary>
</indexterm>
<para>ISDN bridges or routers are not at all specific to FreeBSD
or any other operating system. For a more complete
description of routing and bridging technology, please refer
to a networking reference book.</para>
<para>In the context of this section, the terms router and
bridge will be used interchangeably.</para>
<para>As the cost of low end ISDN routers/bridges comes down, it
will likely become a more and more popular choice. An ISDN
router is a small box that plugs directly into your local
Ethernet network, and manages its own connection to the other
bridge/router. It has built in software to communicate via
PPP and other popular protocols.</para>
<para>A router will allow you much faster throughput than a
standard TA, since it will be using a full synchronous ISDN
connection.</para>
<para>The main problem with ISDN routers and bridges is that
interoperability between manufacturers can still be a problem.
If you are planning to connect to an Internet provider, you
should discuss your needs with them.</para>
<para>If you are planning to connect two LAN segments together,
such as your home LAN to the office LAN, this is the simplest
lowest
maintenance solution. Since you are buying the equipment for
both sides of the connection you can be assured that the link
will work.</para>
<para>For example to connect a home computer or branch office
network to a head office network the following setup could be
used:</para>
<example>
<title>Branch Office or Home Network</title>
<indexterm><primary>10 base 2</primary></indexterm>
<para>Network uses a bus based topology with 10 base 2
Ethernet (<quote>thinnet</quote>). Connect router to
network cable with AUI/10BT transceiver, if
necessary.</para>
<mediaobject>
<imageobject>
<imagedata fileref="advanced-networking/isdn-bus">
</imageobject>
<textobject>
<literallayout class="monospaced">---Sun workstation
|
---FreeBSD box
|
---Windows 95
|
Stand-alone router
|
ISDN BRI line</literallayout>
</textobject>
<textobject>
<phrase>10 Base 2 Ethernet</phrase>
</textobject>
</mediaobject>
<para>If your home/branch office is only one computer you can
use a twisted pair crossover cable to connect to the
stand-alone router directly.</para>
</example>
<example>
<title>Head Office or Other LAN</title>
<indexterm><primary>10 base T</primary></indexterm>
<para>Network uses a star topology with 10 base T Ethernet
(<quote>Twisted Pair</quote>).</para>
<mediaobject>
<imageobject>
<imagedata
fileref="advanced-networking/isdn-twisted-pair">
</imageobject>
<textobject>
<literallayout class="monospaced"> -------Novell Server
| H |
| ---Sun
| |
| U ---FreeBSD
| |
| ---Windows 95
| B |
|___---Stand-alone router
|
ISDN BRI line</literallayout>
</textobject>
<textobject>
<phrase>ISDN Network Diagram</phrase>
</textobject>
</mediaobject>
</example>
<para>One large advantage of most routers/bridges is that they
allow you to have 2 <emphasis>separate independent</emphasis>
PPP connections to 2 separate sites at the
<emphasis>same</emphasis> time. This is not supported on most
TA's, except for specific (usually expensive) models that have
two serial ports. Do not confuse this with channel bonding,
MPP, etc.</para>
<para>This can be a very useful feature if, for example, you
have an dedicated ISDN connection at your office and would
like to tap into it, but do not want to get another ISDN line
at work. A router at the office location can manage a
dedicated B channel connection (64&nbsp;Kbps) to the Internet
and use the other B channel for a separate data connection.
The second B channel can be used for dial-in, dial-out or
dynamically bonding (MPP, etc.) with the first B channel for
more bandwidth.</para>
<indexterm><primary>IPX/SPX</primary></indexterm>
<para>An Ethernet bridge will also allow you to transmit more
than just IP traffic. You can also send IPX/SPX or whatever
other protocols you use.</para>
</sect2>
</sect1>
<sect1 id="network-natd">
<sect1info>
<authorgroup>
<author>
<firstname>Chern</firstname>
<surname>Lee</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Network Address Translation</title>
<sect2 id="network-natoverview">
<title>Overview</title>
<indexterm>
<primary><application>natd</application></primary>
</indexterm>
<para>FreeBSD's Network Address Translation daemon, commonly
known as &man.natd.8; is a daemon that accepts incoming raw IP
packets, changes the source to the local machine and
re-injects these packets back into the outgoing IP packet
stream. &man.natd.8; does this by changing the source IP
address and port such that when data is received back, it is
able to determine the original location of the data and
forward it back to its original requester.</para>
<indexterm>
<primary>Internet connection sharing</primary>
</indexterm>
<indexterm>
<primary>NAT</primary>
</indexterm>
<para>The most common use of NAT is to perform what is commonly
known as Internet Connection Sharing.</para>
</sect2>
<sect2 id="network-natsetup">
<title>Setup</title>
<para>Due to the diminishing IP space in IPv4, and the increased
number of users on high-speed consumer lines such as cable or
DSL, people are increasingly in need of an Internet Connection
Sharing solution. The ability to connect several computers
online through one connection and IP address makes
&man.natd.8; a reasonable choice.</para>
<para>Most commonly, a user has a machine connected to a cable
or DSL line with one IP address and wishes to use this one
connected computer to provide Internet access to several more
over a LAN.</para>
<para>To do this, the FreeBSD machine on the Internet must act
as a gateway. This gateway machine must have two
NICs&mdash;one for connecting to the Internet router, the
other connecting to a LAN. All the machines on the LAN are
connected through a hub or switch.</para>
<note>
<para>There are many ways to get a LAN connected to the
Internet through a &os; gateway. This example will only
cover a gateway with at least two NICs.</para>
</note>
<mediaobject>
<imageobject>
<imagedata fileref="advanced-networking/natd">
</imageobject>
<textobject>
<literallayout class="monospaced"> _______ __________ ________
| | | | | |
| Hub |-----| Client B |-----| Router |----- Internet
|_______| |__________| |________|
|
____|_____
| |
| Client A |
|__________|</literallayout>
</textobject>
<textobject>
<phrase>Network Layout</phrase>
</textobject>
</mediaobject>
<para>A setup like this is commonly used to share an Internet
connection. One of the <acronym>LAN</acronym> machines is
connected to the Internet. The rest of the machines access
the Internet through that <quote>gateway</quote>
machine.</para>
</sect2>
<sect2 id="network-natdloaderconfiguration">
<indexterm>
<primary>boot loader</primary>
<secondary>configuration</secondary>
</indexterm>
<title>Boot Loader Configuration</title>
<para>The kernel features for network address translation with
&man.natd.8; are not enabled in the
<filename>GENERIC</filename> kernel, but they can be preloaded
at boot time, by adding a couple of options to
<filename>/boot/loader.conf</filename>:</para>
<programlisting>ipfw_load="YES"
ipdivert_load="YES"</programlisting>
<para>Additionally, the
<literal>net.inet.ip.fw.default_to_accept</literal> tunable
option may be set to <literal>1</literal>:</para>
<programlisting>net.inet.ip.fw.default_to_accept="1"</programlisting>
<note>
<para>It is a very good idea to set this option during the
first attempts to setup a firewall and NAT gateway. This
way the default policy of &man.ipfw.8; will be
<literal>allow ip from any to any</literal> instead of the
less permissive <literal>deny ip from any to any</literal>,
and it will be slightly more difficult to get locked out of
the system right after a reboot.</para>
</note>
</sect2>
<sect2 id="network-natdkernconfiguration">
<title>Kernel Configuration</title>
<indexterm>
<primary>kernel</primary>
<secondary>configuration</secondary>
</indexterm>
<para>When modules are not an option or if it is preferrable to
build all the required features into the running kernel, the
following options must be in the kernel configuration
file:</para>
<programlisting>options IPFIREWALL
options IPDIVERT</programlisting>
<para>Additionally, at choice, the following may also be
suitable:</para>
<programlisting>options IPFIREWALL_DEFAULT_TO_ACCEPT
options IPFIREWALL_VERBOSE</programlisting>
</sect2>
<sect2 id="network-natdsystemconfiguration">
<title>System Startup Configuration</title>
<para>To enable firewall and NAT support at boot time, the
following must be in <filename>/etc/rc.conf</filename>:</para>
<programlisting>gateway_enable="YES" <co id="co-natd-gateway-enable">
firewall_enable="YES" <co id="co-natd-firewall-enable">
firewall_type="OPEN" <co id="co-natd-firewall-type">
natd_enable="YES"
natd_interface="<replaceable>fxp0</replaceable>" <co id="co-natd-natd-interface">
natd_flags="" <co id="co-natd-natd-flags"></programlisting>
<calloutlist>
<callout arearefs="co-natd-gateway-enable">
<para>Sets up the machine to act as a gateway. Running
<command>sysctl net.inet.ip.forwarding=1</command> would
have the same effect.</para>
</callout>
<callout arearefs="co-natd-firewall-enable">
<para>Enables the firewall rules in
<filename>/etc/rc.firewall</filename> at boot.</para>
</callout>
<callout arearefs="co-natd-firewall-type">
<para>This specifies a predefined firewall ruleset that
allows anything in. See
<filename>/etc/rc.firewall</filename> for additional
types.</para>
</callout>
<callout arearefs="co-natd-natd-interface">
<para>Indicates which interface to forward packets through
(the interface connected to the Internet).</para>
</callout>
<callout arearefs="co-natd-natd-flags">
<para>Any additional configuration options passed to
&man.natd.8; on boot.</para>
</callout>
</calloutlist>
<para>Having the previous options defined in
<filename>/etc/rc.conf</filename> would run
<command>natd -interface fxp0</command> at boot. This can
also be run manually.</para>
<note>
<para>It is also possible to use a configuration file for
&man.natd.8; when there are too many options to pass. In
this case, the configuration file must be defined by adding
the following line to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>natd_flags="-f /etc/natd.conf"</programlisting>
<para>The <filename>/etc/natd.conf</filename> file will
contain a list of configuration options, one per line. For
example the next section case would use the following
file:</para>
<programlisting>redirect_port tcp 192.168.0.2:6667 6667
redirect_port tcp 192.168.0.3:80 80</programlisting>
<para>For more information about the configuration file,
consult the &man.natd.8; manual page about the
<option>-f</option> option.</para>
</note>
<para>Each machine and interface behind the LAN should be
assigned IP address numbers in the private network space as
defined by
<ulink url="ftp://ftp.isi.edu/in-notes/rfc1918.txt">RFC
1918</ulink> and have a default gateway of the
<application>natd</application> machine's internal IP
address.</para>
<para>For example, client <hostid>A</hostid> and
<hostid>B</hostid> behind the LAN have IP addresses of
<hostid role="ipaddr">192.168.0.2</hostid> and
<hostid role="ipaddr">192.168.0.3</hostid>, while the natd
machine's LAN interface has an IP address of
<hostid role="ipaddr">192.168.0.1</hostid>. Client
<hostid>A</hostid> and <hostid>B</hostid>'s default gateway
must be set to that of the <application>natd</application>
machine, <hostid role="ipaddr">192.168.0.1</hostid>. The
<application>natd</application> machine's external, or
Internet interface does not require any special modification
for &man.natd.8; to work.</para>
</sect2>
<sect2 id="network-natdport-redirection">
<title>Port Redirection</title>
<para>The drawback with &man.natd.8; is that the LAN clients are
not accessible from the Internet. Clients on the LAN can make
outgoing connections to the world but cannot receive incoming
ones. This presents a problem if trying to run Internet
services on one of the LAN client machines. A simple way
around this is to redirect selected Internet ports on the
<application>natd</application> machine to a LAN
client.</para>
<para>For example, an IRC server runs on client
<hostid>A</hostid>, and a web server runs on client
<hostid>B</hostid>. For this to work properly, connections
received on ports 6667 (IRC) and 80 (web) must be redirected
to the respective machines.</para>
<para>The <option>-redirect_port</option> must be passed to
&man.natd.8; with the proper options. The syntax is as
follows:</para>
<programlisting> -redirect_port proto targetIP:targetPORT[-targetPORT]
[aliasIP:]aliasPORT[-aliasPORT]
[remoteIP[:remotePORT[-remotePORT]]]</programlisting>
<para>In the above example, the argument should be:</para>
<programlisting> -redirect_port tcp 192.168.0.2:6667 6667
-redirect_port tcp 192.168.0.3:80 80</programlisting>
<para>This will redirect the proper <emphasis>tcp</emphasis>
ports to the LAN client machines.</para>
<para>The <option>-redirect_port</option> argument can be used
to indicate port ranges over individual ports. For example,
<replaceable>tcp 192.168.0.2:2000-3000 2000-3000</replaceable>
would redirect all connections received on ports 2000 to 3000
to ports 2000 to 3000 on client <hostid>A</hostid>.</para>
<para>These options can be used when directly running
&man.natd.8;, placed within the
<literal>natd_flags=""</literal> option in
<filename>/etc/rc.conf</filename>, or passed via a
configuration file.</para>
<para>For further configuration options, consult
&man.natd.8;</para>
</sect2>
<sect2 id="network-natdaddress-redirection">
<title>Address Redirection</title>
<indexterm><primary>address redirection</primary></indexterm>
<para>Address redirection is useful if several IP addresses are
available, yet they must be on one machine. With this,
&man.natd.8; can assign each LAN client its own external IP
address. &man.natd.8; then rewrites outgoing packets from the
LAN clients with the proper external IP address and redirects
all traffic incoming on that particular IP address back to the
specific LAN client. This is also known as static NAT. For
example, the IP addresses
<hostid role="ipaddr">128.1.1.1</hostid>,
<hostid role="ipaddr">128.1.1.2</hostid>, and
<hostid role="ipaddr">128.1.1.3</hostid> belong to the
<application>natd</application> gateway machine.
<hostid role="ipaddr">128.1.1.1</hostid> can be used as the
<application>natd</application> gateway machine's external IP
address, while <hostid role="ipaddr">128.1.1.2</hostid> and
<hostid role="ipaddr">128.1.1.3</hostid> are forwarded back to
LAN clients <hostid>A</hostid> and <hostid>B</hostid>.</para>
<para>The <option>-redirect_address</option> syntax is as
follows:</para>
<programlisting>-redirect_address localIP publicIP</programlisting>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<tbody>
<row>
<entry>localIP</entry>
<entry>The internal IP address of the LAN
client.</entry>
</row>
<row>
<entry>publicIP</entry>
<entry>The external IP address corresponding to the LAN
client.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>In the example, this argument would read:</para>
<programlisting>-redirect_address 192.168.0.2 128.1.1.2
-redirect_address 192.168.0.3 128.1.1.3</programlisting>
<para>Like <option>-redirect_port</option>, these arguments are
also placed within the <literal>natd_flags=""</literal> option
of <filename>/etc/rc.conf</filename>, or passed via a
configuration file. With address redirection, there is no
need for port redirection since all data received on a
particular IP address is redirected.</para>
<para>The external IP addresses on the
<application>natd</application> machine must be active and
aliased to the external interface. Look at &man.rc.conf.5; to
do so.</para>
</sect2>
</sect1>
<sect1 id="network-plip">
<title>Parallel Line IP (PLIP)</title>
<indexterm><primary>PLIP</primary></indexterm>
<indexterm>
<primary>Parallel Line IP</primary>
<see>PLIP</see>
</indexterm>
<para>PLIP lets us run TCP/IP between parallel ports. It is
useful on machines without network cards, or to install on
laptops. In this section, we will discuss:</para>
<itemizedlist>
<listitem>
<para>Creating a parallel (laplink) cable.</para>
</listitem>
<listitem>
<para>Connecting two computers with PLIP.</para>
</listitem>
</itemizedlist>
<sect2 id="network-create-parallel-cable">
<title>Creating a Parallel Cable</title>
<para>You can purchase a parallel cable at most computer supply
stores. If you cannot do that, or you just want to know how
it is done, the following table shows how to make one out of a
normal parallel printer cable.</para>
<table frame="none">
<title>Wiring a Parallel Cable for Networking</title>
<tgroup cols="5">
<thead>
<row>
<entry>A-name</entry>
<entry>A-End</entry>
<entry>B-End</entry>
<entry>Descr.</entry>
<entry>Post/Bit</entry>
</row>
</thead>
<tbody>
<row>
<entry><literallayout>DATA0
-ERROR</literallayout></entry>
<entry><literallayout>2
15</literallayout></entry>
<entry><literallayout>15
2</literallayout></entry>
<entry>Data</entry>
<entry><literallayout>0/0x01
1/0x08</literallayout></entry>
</row>
<row>
<entry><literallayout>DATA1
+SLCT</literallayout></entry>
<entry><literallayout>3
13</literallayout></entry>
<entry><literallayout>13
3</literallayout></entry>
<entry>Data</entry>
<entry><literallayout>0/0x02
1/0x10</literallayout></entry>
</row>
<row>
<entry><literallayout>DATA2
+PE</literallayout></entry>
<entry><literallayout>4
12</literallayout></entry>
<entry><literallayout>12
4</literallayout></entry>
<entry>Data</entry>
<entry><literallayout>0/0x04
1/0x20</literallayout></entry>
</row>
<row>
<entry><literallayout>DATA3
-ACK</literallayout></entry>
<entry><literallayout>5
10</literallayout></entry>
<entry><literallayout>10
5</literallayout></entry>
<entry>Strobe</entry>
<entry><literallayout>0/0x08
1/0x40</literallayout></entry>
</row>
<row>
<entry><literallayout>DATA4
BUSY</literallayout></entry>
<entry><literallayout>6
11</literallayout></entry>
<entry><literallayout>11
6</literallayout></entry>
<entry>Data</entry>
<entry><literallayout>0/0x10
1/0x80</literallayout></entry>
</row>
<row>
<entry>GND</entry>
<entry>18-25</entry>
<entry>18-25</entry>
<entry>GND</entry>
<entry>-</entry>
</row>
</tbody>
</tgroup>
</table>
</sect2>
<sect2 id="network-plip-setup">
<title>Setting Up PLIP</title>
<para>First, you have to get a laplink cable. Then, confirm
that both computers have a kernel with &man.lpt.4; driver
support:</para>
<screen>&prompt.root; <userinput>grep lp /var/run/dmesg.boot</userinput>
lpt0: &lt;Printer&gt; on ppbus0
lpt0: Interrupt-driven port</screen>
<para>The parallel port must be an interrupt driven port, you
should have lines similar to the following in your in the
<filename>/boot/device.hints</filename> file:</para>
<programlisting>hint.ppc.0.at="isa"
hint.ppc.0.irq="7"</programlisting>
<para>Then check if the kernel configuration file has a
<literal>device plip</literal> line or if the
<filename>plip.ko</filename> kernel module is loaded. In both
cases the parallel networking interface should appear when you
use the &man.ifconfig.8; command to display it:</para>
<screen>&prompt.root; <userinput>ifconfig plip0</userinput>
plip0: flags=8810&lt;POINTOPOINT,SIMPLEX,MULTICAST&gt; mtu 1500</screen>
<para>Plug the laplink cable into the parallel interface on
both computers.</para>
<para>Configure the network interface parameters on both sites
as <username>root</username>. For example, if you want to
connect the host <hostid>host1</hostid> with another machine
<hostid>host2</hostid>:</para>
<programlisting> host1 &lt;-----&gt; host2
IP Address 10.0.0.1 10.0.0.2</programlisting>
<para>Configure the interface on <hostid>host1</hostid> by
doing:</para>
<screen>&prompt.root; <userinput>ifconfig plip0 10.0.0.1 10.0.0.2</userinput></screen>
<para>Configure the interface on <hostid>host2</hostid> by
doing:</para>
<screen>&prompt.root; <userinput>ifconfig plip0 10.0.0.2 10.0.0.1</userinput></screen>
<para>You now should have a working connection. Please read the
manual pages &man.lp.4; and &man.lpt.4; for more
details.</para>
<para>You should also add both hosts to
<filename>/etc/hosts</filename>:</para>
<programlisting>127.0.0.1 localhost.my.domain localhost
10.0.0.1 host1.my.domain host1
10.0.0.2 host2.my.domain host2</programlisting>
<para>To confirm the connection works, go to each host and ping
the other. For example, on <hostid>host1</hostid>:</para>
<screen>&prompt.root; <userinput>ifconfig plip0</userinput>
plip0: flags=8851&lt;UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
inet 10.0.0.1 --&gt; 10.0.0.2 netmask 0xff000000
&prompt.root; <userinput>netstat -r</userinput>
Routing tables
Internet:
Destination Gateway Flags Refs Use Netif Expire
host2 host1 UH 0 0 plip0
&prompt.root; <userinput>ping -c 4 host2</userinput>
PING host2 (10.0.0.2): 56 data bytes
64 bytes from 10.0.0.2: icmp_seq=0 ttl=255 time=2.774 ms
64 bytes from 10.0.0.2: icmp_seq=1 ttl=255 time=2.530 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=255 time=2.556 ms
64 bytes from 10.0.0.2: icmp_seq=3 ttl=255 time=2.714 ms
--- host2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max/stddev = 2.530/2.643/2.774/0.103 ms</screen>
</sect2>
</sect1>
<sect1 id="network-ipv6">
<sect1info>
<authorgroup>
<author>
<firstname>Aaron</firstname>
<surname>Kaplan</surname>
<contrib>Originally Written by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Rhodes</surname>
<contrib>Restructured and Added by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Brad</firstname>
<surname>Davis</surname>
<contrib>Extended by </contrib>
</author>
</authorgroup>
</sect1info>
<title>IPv6</title>
<para>IPv6 (also known as IPng <quote>IP next generation</quote>)
is the new version of the well known IP protocol (also known as
<acronym>IPv4</acronym>). Like the other current *BSD systems,
FreeBSD includes the KAME IPv6 reference implementation. So
your FreeBSD system comes with all you will need to experiment
with IPv6. This section focuses on getting IPv6 configured and
running.</para>
<para>In the early 1990s, people became aware of the rapidly
diminishing address space of IPv4. Given the expansion rate of
the Internet there were two major concerns:</para>
<itemizedlist>
<listitem>
<para>Running out of addresses. Today this is not so much of
a concern anymore since RFC1918 private address space
(<hostid role="ipaddr">10.0.0.0/8</hostid>,
<hostid role="ipaddr">172.16.0.0/12</hostid>, and
<hostid role="ipaddr">192.168.0.0/16</hostid>) and Network
Address Translation (<acronym>NAT</acronym>) are being
employed.</para>
</listitem>
<listitem>
<para>Router table entries were getting too large. This is
still a concern today.</para>
</listitem>
</itemizedlist>
<para>IPv6 deals with these and many other issues:</para>
<itemizedlist>
<listitem>
<para>128 bit address space. In other words theoretically
there are
340,282,366,920,938,463,463,374,607,431,768,211,456
addresses available. This means there are approximately
6.67 * 10^27 IPv6 addresses per square meter on our
planet.</para>
</listitem>
<listitem>
<para>Routers will only store network aggregation addresses in
their routing tables thus reducing the average space of a
routing table to 8192 entries.</para>
</listitem>
</itemizedlist>
<para>There are also lots of other useful features of IPv6 such
as:</para>
<itemizedlist>
<listitem>
<para>Address autoconfiguration (<ulink
url="http://www.ietf.org/rfc/rfc2462.txt">RFC2462</ulink>)</para>
</listitem>
<listitem>
<para>Anycast addresses (<quote>one-out-of
many</quote>)</para>
</listitem>
<listitem>
<para>Mandatory multicast addresses</para>
</listitem>
<listitem>
<para>IPsec (IP security)</para>
</listitem>
<listitem>
<para>Simplified header structure</para>
</listitem>
<listitem>
<para>Mobile <acronym>IP</acronym></para>
</listitem>
<listitem>
<para>IPv6-to-IPv4 transition mechanisms</para>
</listitem>
</itemizedlist>
<para>For more information see:</para>
<itemizedlist>
<listitem>
<para>IPv6 overview at <ulink
url="http://playground.sun.com/pub/ipng/html/ipng-main.html">playground.sun.com</ulink></para>
</listitem>
<listitem>
<para><ulink url="http://www.kame.net">KAME.net</ulink></para>
</listitem>
</itemizedlist>
<sect2>
<title>Background on IPv6 Addresses</title>
<para>There are different types of IPv6 addresses: Unicast,
Anycast and Multicast.</para>
<para>Unicast addresses are the well known addresses. A packet
sent to a unicast address arrives exactly at the interface
belonging to the address.</para>
<para>Anycast addresses are syntactically indistinguishable from
unicast addresses but they address a group of interfaces. The
packet destined for an anycast address will arrive at the
nearest (in router metric) interface. Anycast addresses may
only be used by routers.</para>
<para>Multicast addresses identify a group of interfaces. A
packet destined for a multicast address will arrive at all
interfaces belonging to the multicast group.</para>
<note>
<para>The IPv4 broadcast address (usually
<hostid role="ipaddr">xxx.xxx.xxx.255</hostid>) is expressed
by multicast addresses in IPv6.</para>
</note>
<table frame="none">
<title>Reserved IPv6 Addresses</title>
<tgroup cols="4">
<thead>
<row>
<entry>IPv6 address</entry>
<entry>Prefixlength (Bits)</entry>
<entry>Description</entry>
<entry>Notes</entry>
</row>
</thead>
<tbody>
<row>
<entry><hostid role="ip6addr">::</hostid></entry>
<entry>128 bits</entry>
<entry>unspecified</entry>
<entry>cf. <hostid role="ipaddr">0.0.0.0</hostid> in
IPv4</entry>
</row>
<row>
<entry><hostid role="ip6addr">::1</hostid></entry>
<entry>128 bits</entry>
<entry>loopback address</entry>
<entry>cf. <hostid role="ipaddr">127.0.0.1</hostid> in
IPv4</entry>
</row>
<row>
<entry><hostid
role="ip6addr">::00:xx:xx:xx:xx</hostid></entry>
<entry>96 bits</entry>
<entry>embedded IPv4</entry>
<entry>The lower 32 bits are the IPv4 address. Also
called <quote>IPv4 compatible IPv6
address</quote></entry>
</row>
<row>
<entry><hostid
role="ip6addr">::ff:xx:xx:xx:xx</hostid></entry>
<entry>96 bits</entry>
<entry>IPv4 mapped IPv6 address</entry>
<entry>The lower 32 bits are the IPv4 address.
For hosts which do not support IPv6.</entry>
</row>
<row>
<entry><hostid role="ip6addr">fe80::</hostid> - <hostid
role="ip6addr">feb::</hostid></entry>
<entry>10 bits</entry>
<entry>link-local</entry>
<entry>cf. loopback address in IPv4</entry>
</row>
<row>
<entry><hostid role="ip6addr">fec0::</hostid> - <hostid
role="ip6addr">fef::</hostid></entry>
<entry>10 bits</entry>
<entry>site-local</entry>
<entry>&nbsp;</entry>
</row>
<row>
<entry><hostid role="ip6addr">ff::</hostid></entry>
<entry>8 bits</entry>
<entry>multicast</entry>
<entry>&nbsp;</entry>
</row>
<row>
<entry><hostid role="ip6addr">001</hostid> (base
2)</entry>
<entry>3 bits</entry>
<entry>global unicast</entry>
<entry>All global unicast addresses are assigned from
this pool. The first 3 bits are
<quote>001</quote>.</entry>
</row>
</tbody>
</tgroup>
</table>
</sect2>
<sect2>
<title>Reading IPv6 Addresses</title>
<para>The canonical form is represented as:
<hostid role="ip6addr">x:x:x:x:x:x:x:x</hostid>, each
<quote>x</quote> being a 16 Bit hex value. For example
<hostid
role="ip6addr">FEBC:A574:382B:23C1:AA49:4592:4EFE:9982</hostid></para>
<para>Often an address will have long substrings of all zeros
therefore one such substring per address can be abbreviated by
<quote>::</quote>. Also up to three leading <quote>0</quote>s
per hexquad can be omitted. For example
<hostid role="ip6addr">fe80::1</hostid> corresponds to the
canonical form <hostid
role="ip6addr">fe80:0000:0000:0000:0000:0000:0000:0001</hostid>.</para>
<para>A third form is to write the last 32 Bit part in the
well known (decimal) IPv4 style with dots <quote>.</quote>
as separators. For example
<hostid role="ip6addr">2002::10.0.0.1</hostid>
corresponds to the (hexadecimal) canonical representation
<hostid
role="ip6addr">2002:0000:0000:0000:0000:0000:0a00:0001</hostid>
which in turn is equivalent to writing
<hostid role="ip6addr">2002::a00:1</hostid>.</para>
<para>By now the reader should be able to understand the
following:</para>
<screen>&prompt.root; <userinput>ifconfig</userinput></screen>
<programlisting>rl0: flags=8943&lt;UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST&gt; mtu 1500
inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255
inet6 fe80::200:21ff:fe03:8e1%rl0 prefixlen 64 scopeid 0x1
ether 00:00:21:03:08:e1
media: Ethernet autoselect (100baseTX )
status: active</programlisting>
<para><hostid
role="ip6addr">fe80::200:21ff:fe03:8e1%rl0</hostid>
is an auto configured link-local address. It is generated
from the MAC address as part of the auto configuration.</para>
<para>For further information on the structure of IPv6 addresses
see <ulink
url="http://www.ietf.org/rfc/rfc3513.txt">RFC3513</ulink>.</para>
</sect2>
<sect2>
<title>Getting Connected</title>
<para>Currently there are four ways to connect to other IPv6
hosts and networks:</para>
<itemizedlist>
<listitem>
<para>Contact your Internet Service Provider to see if they
offer IPv6 yet.</para>
</listitem>
<listitem>
<para><ulink url="http://www.sixxs.net">SixXS</ulink> offers
tunnels with end-points all around the globe.</para>
</listitem>
<listitem>
<para>Tunnel via 6-to-4 (<ulink
url="http://www.ietf.org/rfc/rfc3068.txt">RFC3068</ulink>)</para>
</listitem>
<listitem>
<para>Use the
<filename role="package">net/freenet6</filename> port if
you are on a dial-up connection.</para>
</listitem>
</itemizedlist>
</sect2>
<sect2>
<title>DNS in the IPv6 World</title>
<para>There used to be two types of DNS records for IPv6. The
IETF has declared A6 records obsolete. AAAA records are the
standard now.</para>
<para>Using AAAA records is straightforward. Assign your
hostname to the new IPv6 address you just received by
adding:</para>
<programlisting>MYHOSTNAME AAAA MYIPv6ADDR</programlisting>
<para>To your primary zone DNS file. In case you do not serve
your own <acronym>DNS</acronym> zones ask your
<acronym>DNS</acronym> provider. Current versions of
<application>bind</application> (version 8.3 and 9) and
<filename role="package">dns/djbdns</filename> (with the IPv6
patch) support AAAA records.</para>
</sect2>
<sect2>
<title>Applying the Needed Changes to
<filename>/etc/rc.conf</filename></title>
<sect3>
<title>IPv6 Client Settings</title>
<para>These settings will help you configure a machine that
will be on your LAN and act as a client, not a router. To
have &man.rtsol.8; autoconfigure your interface on boot on
&os;&nbsp;9.<replaceable>x</replaceable> and later,
add:</para>
<programlisting>ipv6_prefer="YES"</programlisting>
<para>to <filename>rc.conf</filename>.</para>
<para>For &os;&nbsp;8.<replaceable>x</replaceable> and
earlier, add:</para>
<programlisting>ipv6_enable="YES"</programlisting>
<para>To statically assign an IP address such as <hostid
role="ip6addr">2001:471:1f11:251:290:27ff:fee0:2093</hostid>,
to your <devicename>fxp0</devicename> interface, add the
following for &os;&nbsp;9.<replaceable>x</replaceable>:</para>
<programlisting>ifconfig_fxp0_ipv6="inet6 2001:471:1f11:251:290:27ff:fee0:2093 prefixlen <replaceable>64</replaceable>"</programlisting>
<note>
<para>Be sure to change <replaceable>prefixlen
64</replaceable> to the appropriate value for the subnet
within which the computer is networked.</para>
</note>
<para>For &os;&nbsp;8<replaceable>x</replaceable> and earlier,
add:</para>
<programlisting>ipv6_ifconfig_fxp0="2001:471:1f11:251:290:27ff:fee0:2093"</programlisting>
<para>To assign a default router of
<hostid role="ip6addr">2001:471:1f11:251::1</hostid> add the
following to <filename>/etc/rc.conf</filename>:</para>
<programlisting>ipv6_defaultrouter="2001:471:1f11:251::1"</programlisting>
</sect3>
<sect3>
<title>IPv6 Router/Gateway Settings</title>
<para>This will help you take the directions that your tunnel
provider has given you and convert it into settings that
will persist through reboots. To restore your tunnel on
startup use something like the following in
<filename>/etc/rc.conf</filename>:</para>
<para>List the Generic Tunneling interfaces that will be
configured, for example
<devicename>gif0</devicename>:</para>
<programlisting>gif_interfaces="gif0"</programlisting>
<para>To configure the interface with a local endpoint of
<replaceable>MY_IPv4_ADDR</replaceable> to a remote endpoint
of <replaceable>REMOTE_IPv4_ADDR</replaceable>:</para>
<programlisting>gifconfig_gif0="<replaceable>MY_IPv4_ADDR REMOTE_IPv4_ADDR</replaceable>"</programlisting>
<para>To apply the IPv6 address you have been assigned for use
as your IPv6 tunnel endpoint, add the following for
&os;&nbsp;9.<replaceable>x</replaceable> and later:</para>
<programlisting>ifconfig_gif0_ipv6="inet6 <replaceable>MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR</replaceable>"</programlisting>
<para>For &os;&nbsp;8.<replaceable>x</replaceable> and
earlier, add:</para>
<programlisting>ipv6_ifconfig_gif0="<replaceable>MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR</replaceable>"</programlisting>
<para>Then all you have to do is set the default route for
IPv6. This is the other side of the IPv6 tunnel:</para>
<programlisting>ipv6_defaultrouter="<replaceable>MY_IPv6_REMOTE_TUNNEL_ENDPOINT_ADDR</replaceable>"</programlisting>
</sect3>
<sect3>
<title>IPv6 Tunnel Settings</title>
<para>If the server is to route IPv6 between the rest of your
network and the world, the following
<filename>/etc/rc.conf</filename> setting will also be
needed:</para>
<programlisting>ipv6_gateway_enable="YES"</programlisting>
</sect3>
</sect2>
<sect2>
<title>Router Advertisement and Host Auto Configuration</title>
<para>This section will help you setup &man.rtadvd.8; to
advertise the IPv6 default route.</para>
<para>To enable &man.rtadvd.8; you will need the following in
your <filename>/etc/rc.conf</filename>:</para>
<programlisting>rtadvd_enable="YES"</programlisting>
<para>It is important that you specify the interface on which to
do IPv6 router solicitation. For example to tell
&man.rtadvd.8; to use <devicename>fxp0</devicename>:</para>
<programlisting>rtadvd_interfaces="fxp0"</programlisting>
<para>Now we must create the configuration file,
<filename>/etc/rtadvd.conf</filename>. Here is an
example:</para>
<programlisting>fxp0:\
:addrs#1:addr="2001:471:1f11:246::":prefixlen#64:tc=ether:</programlisting>
<para>Replace <devicename>fxp0</devicename> with the interface
you are going to be using.</para>
<para>Next, replace
<hostid role="ip6addr">2001:471:1f11:246::</hostid> with the
prefix of your allocation.</para>
<para>If you are dedicated a <hostid role="netmask">/64</hostid>
subnet you will not need to change anything else. Otherwise,
you will need to change the <literal>prefixlen#</literal> to
the correct value.</para>
</sect2>
</sect1>
<sect1 id="network-atm">
<sect1info>
<authorgroup>
<author>
<firstname>Harti</firstname>
<surname>Brandt</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Asynchronous Transfer Mode (ATM)</title>
<sect2>
<title>Configuring Classical IP over ATM (PVCs)</title>
<para>Classical IP over ATM (<acronym>CLIP</acronym>) is the
simplest method to use Asynchronous Transfer Mode (ATM)
with IP. It can be used with
switched connections (SVCs) and with permanent connections
(PVCs). This section describes how to set up a network based
on PVCs.</para>
<sect3>
<title>Fully Meshed Configurations</title>
<para>The first method to set up a <acronym>CLIP</acronym>
with PVCs is to connect each machine to each other machine
in the network via a dedicated PVC. While this is simple to
configure it tends to become impractical for a larger number
of machines. The example supposes that we have four
machines in the network, each connected to the
<acronym role="Asynchronous Transfer Mode">ATM</acronym>
network with an
<acronym role="Asynchronous Transfer Mode">ATM</acronym>
adapter card. The first step is the planning of the IP
addresses and the
<acronym role="Asynchronous Transfer Mode">ATM</acronym>
connections between the machines. We use the
following:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<colspec colwidth="1*">
<colspec colwidth="1*">
<thead>
<row>
<entry>Host</entry>
<entry>IP Address</entry>
</row>
</thead>
<tbody>
<row>
<entry><hostid>hostA</hostid></entry>
<entry><hostid
role="ipaddr">192.168.173.1</hostid></entry>
</row>
<row>
<entry><hostid>hostB</hostid></entry>
<entry><hostid
role="ipaddr">192.168.173.2</hostid></entry>
</row>
<row>
<entry><hostid>hostC</hostid></entry>
<entry><hostid
role="ipaddr">192.168.173.3</hostid></entry>
</row>
<row>
<entry><hostid>hostD</hostid></entry>
<entry><hostid
role="ipaddr">192.168.173.4</hostid></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>To build a fully meshed net we need one ATM connection
between each pair of machines:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<colspec colwidth="1*">
<colspec colwidth="1*">
<thead>
<row>
<entry>Machines</entry>
<entry>VPI.VCI couple</entry>
</row>
</thead>
<tbody>
<row>
<entry><hostid>hostA</hostid> -
<hostid>hostB</hostid></entry>
<entry>0.100</entry>
</row>
<row>
<entry><hostid>hostA</hostid> -
<hostid>hostC</hostid></entry>
<entry>0.101</entry>
</row>
<row>
<entry><hostid>hostA</hostid> -
<hostid>hostD</hostid></entry>
<entry>0.102</entry>
</row>
<row>
<entry><hostid>hostB</hostid> -
<hostid>hostC</hostid></entry>
<entry>0.103</entry>
</row>
<row>
<entry><hostid>hostB</hostid> -
<hostid>hostD</hostid></entry>
<entry>0.104</entry>
</row>
<row>
<entry><hostid>hostC</hostid> -
<hostid>hostD</hostid></entry>
<entry>0.105</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>The VPI and VCI values at each end of the connection may
of course differ, but for simplicity we assume that they are
the same. Next we need to configure the ATM interfaces on
each host:</para>
<screen>hostA&prompt.root; <userinput>ifconfig hatm0 192.168.173.1 up</userinput>
hostB&prompt.root; <userinput>ifconfig hatm0 192.168.173.2 up</userinput>
hostC&prompt.root; <userinput>ifconfig hatm0 192.168.173.3 up</userinput>
hostD&prompt.root; <userinput>ifconfig hatm0 192.168.173.4 up</userinput></screen>
<para>assuming that the ATM interface is
<devicename>hatm0</devicename> on all hosts. Now the PVCs
need to be configured on <hostid>hostA</hostid> (we assume
that they are already configured on the ATM switches, you
need to consult the manual for the switch on how to do
this).</para>
<screen>hostA&prompt.root; <userinput>atmconfig natm add 192.168.173.2 hatm0 0 100 llc/snap ubr</userinput>
hostA&prompt.root; <userinput>atmconfig natm add 192.168.173.3 hatm0 0 101 llc/snap ubr</userinput>
hostA&prompt.root; <userinput>atmconfig natm add 192.168.173.4 hatm0 0 102 llc/snap ubr</userinput>
hostB&prompt.root; <userinput>atmconfig natm add 192.168.173.1 hatm0 0 100 llc/snap ubr</userinput>
hostB&prompt.root; <userinput>atmconfig natm add 192.168.173.3 hatm0 0 103 llc/snap ubr</userinput>
hostB&prompt.root; <userinput>atmconfig natm add 192.168.173.4 hatm0 0 104 llc/snap ubr</userinput>
hostC&prompt.root; <userinput>atmconfig natm add 192.168.173.1 hatm0 0 101 llc/snap ubr</userinput>
hostC&prompt.root; <userinput>atmconfig natm add 192.168.173.2 hatm0 0 103 llc/snap ubr</userinput>
hostC&prompt.root; <userinput>atmconfig natm add 192.168.173.4 hatm0 0 105 llc/snap ubr</userinput>
hostD&prompt.root; <userinput>atmconfig natm add 192.168.173.1 hatm0 0 102 llc/snap ubr</userinput>
hostD&prompt.root; <userinput>atmconfig natm add 192.168.173.2 hatm0 0 104 llc/snap ubr</userinput>
hostD&prompt.root; <userinput>atmconfig natm add 192.168.173.3 hatm0 0 105 llc/snap ubr</userinput></screen>
<para>Of course other traffic contracts than UBR can be used
given the ATM adapter supports those. In this case the name
of the traffic contract is followed by the parameters of the
traffic. Help for the &man.atmconfig.8; tool can be
obtained with:</para>
<screen>&prompt.root; <userinput>atmconfig help natm add</userinput></screen>
<para>or in the &man.atmconfig.8; manual page.</para>
<para>The same configuration can also be done via
<filename>/etc/rc.conf</filename>. For
<hostid>hostA</hostid> this would look like:</para>
<programlisting>network_interfaces="lo0 hatm0"
ifconfig_hatm0="inet 192.168.173.1 up"
natm_static_routes="hostB hostC hostD"
route_hostB="192.168.173.2 hatm0 0 100 llc/snap ubr"
route_hostC="192.168.173.3 hatm0 0 101 llc/snap ubr"
route_hostD="192.168.173.4 hatm0 0 102 llc/snap ubr"</programlisting>
<para>The current state of all <acronym>CLIP</acronym> routes
can be obtained with:</para>
<screen>hostA&prompt.root; <userinput>atmconfig natm show</userinput></screen>
</sect3>
</sect2>
</sect1>
<sect1 id="carp">
<sect1info>
<authorgroup>
<author>
<firstname>Tom</firstname>
<surname>Rhodes</surname>
<contrib>Contributed by </contrib>
</author>
</authorgroup>
</sect1info>
<title>Common Address Redundancy Protocol (CARP)</title>
<indexterm>
<primary>CARP</primary>
</indexterm>
<indexterm>
<primary>Common Address Redundancy Protocol</primary>
</indexterm>
<para>The Common Address Redundancy Protocol, or
<acronym>CARP</acronym> allows multiple hosts to share the same
<acronym>IP</acronym> address. In some configurations, this may
be used for availability or load balancing. Hosts may use
separate <acronym>IP</acronym> addresses as well, as in the
example provided here.</para>
<para>To enable support for <acronym>CARP</acronym>, the &os;
kernel must be rebuilt as described in
<xref linkend="kernelconfig"> with the following option:</para>
<programlisting>device carp</programlisting>
<para>Alternatively, the <filename>if_carp.ko</filename> module
can be loaded at boot time. Add the following line to the
<filename>/boot/loader.conf</filename>:</para>
<programlisting>if_carp_load="YES"</programlisting>
<para><acronym>CARP</acronym> functionality should now be
available and may be tuned via several <command>sysctl</command>
<acronym>OID</acronym>s:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="2">
<thead>
<row>
<entry>OID</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><varname>net.inet.carp.allow</varname></entry>
<entry>Accept incoming <acronym>CARP</acronym> packets.
Enabled by default.</entry>
</row>
<row>
<entry><varname>net.inet.carp.preempt</varname></entry>
<entry>This option downs all of the
<acronym>CARP</acronym> interfaces on the host when one
of them goes down. Disabled by default</entry>
</row>
<row>
<entry><varname>net.inet.carp.log</varname></entry>
<entry>A value of <literal>0</literal> disables any
logging. A Value of <literal>1</literal> enables
logging of bad <acronym>CARP</acronym> packets. Values
greater than <literal>1</literal> enables logging of
state changes for the <acronym>CARP</acronym>
interfaces. The default value is
<literal>1</literal>.</entry>
</row>
<row>
<entry><varname>net.inet.carp.arpbalance</varname></entry>
<entry>Balance local network traffic using
<acronym>ARP</acronym>. Disabled by default.</entry>
</row>
<row>
<entry><varname>net.inet.carp.suppress_preempt</varname></entry>
<entry>A read only <acronym>OID</acronym> showing the
status of preemption suppression. Preemption can be
suppressed if link on an interface is down. A value of
<literal>0</literal>, means that preemption is not
suppressed. Every problem increments this
<acronym>OID</acronym>.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>The <acronym>CARP</acronym> devices themselves may be
created via the <command>ifconfig</command> command:</para>
<screen>&prompt.root; <userinput>ifconfig carp0 create</userinput></screen>
<para>In a real environment, these interfaces will need unique
identification numbers known as a <acronym>VHID</acronym>. This
<acronym>VHID</acronym> or Virtual Host Identification will be
used to distinguish the host on the network.</para>
<sect2>
<title>Using CARP for Server Availability (CARP)</title>
<para>One use of <acronym>CARP</acronym>, as noted above, is for
server availability. This example will provide failover
support for three hosts, all with unique <acronym>IP</acronym>
addresses and providing the same web content. These machines
will act in conjunction with a Round Robin
<acronym>DNS</acronym> configuration. The failover machine
will have two additional <acronym>CARP</acronym> interfaces,
one for each of the content server's <acronym>IP</acronym>s.
When a failure occurs, the failover server should pick up the
failed machine's <acronym>IP</acronym> address. This means
the failure should go completely unnoticed to the user. The
failover server requires identical content and services as the
other content servers it is expected to pick up load
for.</para>
<para>The two machines should be configured identically other
than their issued hostnames and <acronym>VHID</acronym>s.
This example calls these machines
<hostid>hosta.example.org</hostid> and
<hostid>hostb.example.org</hostid> respectively. First, the
required lines for a <acronym>CARP</acronym> configuration
have to be added to <filename>rc.conf</filename>. For
<hostid>hosta.example.org</hostid>, the
<filename>rc.conf</filename> file should contain the following
lines:</para>
<programlisting>hostname="hosta.example.org"
ifconfig_fxp0="inet 192.168.1.3 netmask 255.255.255.0"
cloned_interfaces="carp0"
ifconfig_carp0="vhid 1 pass testpass 192.168.1.50/24"</programlisting>
<para>On <hostid>hostb.example.org</hostid> the following lines
should be in <filename>rc.conf</filename>:</para>
<programlisting>hostname="hostb.example.org"
ifconfig_fxp0="inet 192.168.1.4 netmask 255.255.255.0"
cloned_interfaces="carp0"
ifconfig_carp0="vhid 2 pass testpass 192.168.1.51/24"</programlisting>
<note>
<para>It is very important that the passwords, specified by
the <option>pass</option> option to
<command>ifconfig</command>, are identical. The
<devicename>carp</devicename> devices will only listen to
and accept advertisements from machines with the correct
password. The <acronym>VHID</acronym> must also be
different for each machine.</para>
</note>
<para>The third machine, <hostid>provider.example.org</hostid>,
should be prepared so that it may handle failover from either
host. This machine will require two
<devicename>carp</devicename> devices, one to handle each
host. The appropriate <filename>rc.conf</filename>
configuration lines will be similar to the following:</para>
<programlisting>hostname="provider.example.org"
ifconfig_fxp0="inet 192.168.1.5 netmask 255.255.255.0"
cloned_interfaces="carp0 carp1"
ifconfig_carp0="vhid 1 advskew 100 pass testpass 192.168.1.50/24"
ifconfig_carp1="vhid 2 advskew 100 pass testpass 192.168.1.51/24"</programlisting>
<para>Having the two <devicename>carp</devicename> devices will
allow <hostid>provider.example.org</hostid> to notice and pick
up the <acronym>IP</acronym> address of either machine should
it stop responding.</para>
<note>
<para>The default &os; kernel <emphasis>may</emphasis> have
preemption enabled. If so,
<hostid>provider.example.org</hostid> may not relinquish the
<acronym>IP</acronym> address back to the original content
server. In this case, an administrator may have to manually
force the IP back to the master. The following command
should be issued on
<hostid>provider.example.org</hostid>:</para>
<screen>&prompt.root; <userinput>ifconfig carp0 down && ifconfig carp0 up</userinput></screen>
<para>This should be done on the <devicename>carp</devicename>
interface which corresponds to the correct host.</para>
</note>
<para>At this point, <acronym>CARP</acronym> should be
completely enabled and available for testing. For testing,
either networking has to be restarted or the machines need to
be rebooted.</para>
<para>More information is always available in the &man.carp.4;
manual page.</para>
</sect2>
</sect1>
</chapter>
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