<?xml version="1.0" encoding="big5"?>
<!--
The FreeBSD Documentation Project
$FreeBSD$
Original revision: 1.402
-->
<chapter id="advanced-networking">
<title>網路進階練功房</title>
<sect1 id="advanced-networking-synopsis">
<title>概述</title>
<para>本章將介紹一些進階的網路設定主題。</para>
<para>讀完這章，您將了解：</para>
<itemizedlist>
<listitem>
<para>gateway(閘道)及 route(路由)的概念。</para>
</listitem>
<listitem>
<para>如何設定 IEEE 802.11 以及藍芽(&bluetooth;)設備。</para>
</listitem>
<listitem>
<para>如何以 FreeBSD 作為 bridge(橋接)。</para>
</listitem>
<listitem>
<para>如何為無碟系統設定網路開機。</para>
</listitem>
<listitem>
<para>如何設定 NAT(Network Address Translation)。</para>
</listitem>
<listitem>
<para>如何透過 PLIP 方式來連接兩台電腦。</para>
</listitem>
<listitem>
<para>如何在 FreeBSD 內設定 IPv6。</para>
</listitem>
<listitem>
<para>如何設定 ATM。</para>
</listitem>
<listitem>
<para>如何去善用 &os; 的 CARP(Common Access Redundancy Protocol)功能
。</para>
</listitem>
</itemizedlist>
<para>在開始閱讀這章之前，您需要︰</para>
<itemizedlist>
<listitem>
<para>瞭解 <filename>/etc/rc</filename> 相關 script 的概念。</para>
</listitem>
<listitem>
<para>熟悉基本常用的網路術語。</para>
</listitem>
<listitem>
<para>知道如何設定、安裝新的 FreeBSD kernel (<xref
linkend="kernelconfig"/>)。</para>
</listitem>
<listitem>
<para>知道如何透過 port/package 安裝軟體 (<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>為了讓一部電腦能找到另一部電腦，因此必需要有一種機制，
讓這部電腦知道該怎麼做，這個機制就是路由選擇
(<firstterm>routing</firstterm>)。
一條路由(<quote>route</quote>)是由一對位址所定義的：一個是
<quote>目的地(destination)</quote>以及另一個則是閘道
(<quote>gateway</quote>)。
這對位址表示要送到<emphasis>目的地</emphasis>的封包，
必須經過<emphasis>閘道</emphasis>。
目的地分為三種類型：主機、子網路(subnet)、預設路由(
<quote>default route</quote>。 若都沒有其它的路由可以使用，
這時就會使用預設路由，稍後我們會對預設路由作進一步的說明。 此外，
閘道也可分為三種類型：主機、傳輸介面(interface，也稱為
<quote>links</quote>)、乙太網路硬體位址(MAC addresses)。</para>
<sect2>
<title>範例</title>
<para>為了方便說明不同類型的路由選擇(routing)，以下使用
<command>netstat</command> 指令的結果作為介紹範例：</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>=></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] <--ether--> [Local1] <--PPP--> [ISP-Serv] <--ether--> [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>
<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>
<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>
<indexterm><primary>BGP</primary></indexterm>
<indexterm><primary>RIP</primary></indexterm>
<indexterm><primary>OSPF</primary></indexterm>
</sect2>
<sect2>
<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
10.0.0/24 link#1 UC 0 0 xl0
192.168.1/24 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>
<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>
<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>
<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>
</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>Since the 6.0 version, &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 driver proper (&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 you load this support as
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 can be found at the beginning
of the &man.wlan.4; manual page. 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>With a device driver configured you need to also bring
in the 802.11 networking support required by the driver.
For the &man.ath.4; driver this is at least the &man.wlan.4;
module; this module is automatically loaded with the
wireless device driver. 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 is to run totally open (i.e., with no encryption)
then you do not even need the &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 just 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 ath # Atheros IEEE 802.11 wireless network driver
device ath_hal # Atheros Hardware Access Layer
device ath_rate_sample # John Bicket's SampleRate control algorithm.
device wlan # 802.11 support (Required)
device wlan_wep # WEP crypto support for 802.11 devices
device wlan_ccmp # AES-CCMP crypto support for 802.11 devices
device wlan_tkip # TKIP and Michael crypto support for 802.11 devices</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: <Atheros 5212> mem 0xff9f0000-0xff9fffff irq 17 at device 2.0 on pci2
ath0: Ethernet address: 00:11:95:d5:43:62
ath0: mac 7.9 phy 4.5 radio 5.6</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>ath0</replaceable> up scan</userinput>
SSID BSSID CHAN RATE S:N INT CAPS
dlinkap 00:13:46:49:41:76 6 54M 29:0 100 EPS WPA WME
freebsdap 00:11:95:c3:0d:ac 1 54M 22:0 100 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>
<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>
<variablelist>
<varlistentry>
<term><literal>E</literal></term>
<listitem>
<para>Extended Service Set (ESS). Indicates that the
station is part of an infrastructure network (in
contrast to an IBSS/ad-hoc network).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>I</literal></term>
<listitem>
<para>IBSS/ad-hoc network. Indicates that the station
is part of an ad-hoc network (in contrast to an ESS
network).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>P</literal></term>
<listitem>
<para>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.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>S</literal></term>
<listitem>
<para>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).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>s</literal></term>
<listitem>
<para>Short slot time. Indicates that the 802.11g
network is using a short slot time because there are
no legacy (802.11b) stations present.</para>
</listitem>
</varlistentry>
</variablelist>
<para>One can also display the current list of known
networks with:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</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>ifconfig_ath0="DHCP"</programlisting>
<para>If there are multiple access points and you want to
select a specific one, you can select it by its
SSID:</para>
<programlisting>ifconfig_ath0="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>ifconfig_ath0="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>ifconfig_ath0="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>ifconfig_ath0="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,
simply 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>ifconfig_ath0="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>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.1.100 netmask 0xffffff00 broadcast 192.168.1.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/54Mbps)
status: associated
ssid dlinkap channel 6 bssid 00:13:46:49:41:76
authmode OPEN privacy OFF txpowmax 36 protmode CTS bintval 100</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</literal> line informs you that the
communication is not encrypted
(<literal>OPEN</literal>).</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>ifconfig_ath0="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) which 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 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>ifconfig_ath0="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 ath0 to 255.255.255.255 port 67 interval 5
DHCPDISCOVER on ath0 to 255.255.255.255 port 67 interval 6
DHCPOFFER from 192.168.0.1
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.1
bound to 192.168.0.254 -- renewal in 300 seconds.
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/36Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA privacy ON deftxkey UNDEF TKIP 2:128-bit txpowmax 36
protmode CTS roaming MANUAL bintval 100</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>ath0</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=TKIP GTK=TKIP]</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>ath0</replaceable></userinput>
DHCPREQUEST on ath0 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>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/48Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA privacy ON deftxkey UNDEF TKIP 2:128-bit txpowmax 36
protmode CTS roaming MANUAL bintval 100</screen>
<note>
<para>If the <filename>/etc/rc.conf</filename> is set up
with the line <literal>ifconfig_ath0="DHCP"</literal>
then it is no need to run the
<command>dhclient</command> command manually,
<command>dhclient</command> will be launched after
<command>wpa_supplicant</command> plumbs the
keys.</para>
</note>
<para>In the case where the use of DHCP is not possible,
you can set a static IP address after
<command>wpa_supplicant</command> has authenticated the
station:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> inet <replaceable>192.168.0.100</replaceable> netmask <replaceable>255.255.255.0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.100 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/36Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA privacy ON deftxkey UNDEF TKIP 2:128-bit txpowmax 36
protmode CTS roaming MANUAL bintval 100</screen>
<para>When DHCP is not used, you also have to manually set
up 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>" >> /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 make difference with the less secure
WPA-Personal with its pre-shared key. The
authentication in WPA-Enterprise is based on EAP
(Extensible Authentication Protocol).</para>
<para>EAP does not come with an encryption method, it was
decided to embed EAP inside an encrypted tunnel. Many
types of EAP authentication methods have been designed,
the most common methods are EAP-TLS, EAP-TTLS and
EAP-PEAP.</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 certificat.</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 line to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_ath0="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 ath0 to 255.255.255.255 port 67
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (DS/11Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA2/802.11i privacy ON deftxkey UNDEF TKIP 2:128-bit
txpowmax 36 protmode CTS roaming MANUAL bintval 100</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 certificat.</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 line to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_ath0="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 ath0 to 255.255.255.255 port 67
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (DS/11Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA2/802.11i privacy ON deftxkey UNDEF TKIP 2:128-bit
txpowmax 36 protmode CTS roaming MANUAL bintval 100</screen>
</sect5>
<sect5 id="network-wireless-wpa-eap-peap">
<title>WPA with EAP-PEAP</title>
<para>PEAP (Protected EAP) has been designed as an
alternative to EAP-TTLS. There are two types of PEAP
methods, the most common one is PEAPv0/EAP-MSCHAPv2. In
the rest of this document, we will use the PEAP term to
refer to that EAP method. PEAP 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 term of
security the difference between EAP-TTLS and PEAP is
that PEAP authentication broadcasts the username in
clear, only the password is 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 certificat.</para>
</callout>
<callout arearefs="co-peap-pha1">
<para>This field contains the parameters for the
first phase of the authentication (the TLS
tunnel). According to the authentication server
used, you will have to specify a specific label
for the authentication. Most of 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>ifconfig_ath0="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 ath0 to 255.255.255.255 port 67
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPREQUEST on ath0 to 255.255.255.255 port 67
DHCPACK from 192.168.0.20
bound to 192.168.0.254 -- renewal in 300 seconds.
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (DS/11Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode WPA2/802.11i privacy ON deftxkey UNDEF TKIP 2:128-bit
txpowmax 36 protmode CTS roaming MANUAL bintval 100</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 to be
cracked.</para>
<para>WEP can be set up with
<command>ifconfig</command>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> inet <replaceable>192.168.1.100</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid my_net \
wepmode on weptxkey 3 wepkey 3:0x3456789012</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.</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>
<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 &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>ath0</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 adresses
and a SSID.</para>
<para>On the box <hostid>A</hostid>:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable> mediaopt adhoc</userinput>
&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
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 <adhoc> (autoselect <adhoc>)
status: associated
ssid freebsdap channel 2 bssid 02:11:95:c3:0d:ac
authmode OPEN privacy OFF txpowmax 36 protmode CTS bintval 100</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>ath0</replaceable> up scan</userinput>
SSID BSSID CHAN RATE S:N INT CAPS
freebsdap 02:11:95:c3:0d:ac 2 54M 19:0 100 IS</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>ath0</replaceable> inet <replaceable>192.168.0.2</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>freebsdap</replaceable> mediaopt adhoc</userinput>
&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect <adhoc> (autoselect <adhoc>)
status: associated
ssid freebsdap channel 2 bssid 02:11:95:c3:0d:ac
authmode OPEN privacy OFF txpowmax 36 protmode CTS bintval 100</screen>
<para>Both <hostid>A</hostid> and <hostid>B</hostid> are now
ready to exchange informations.</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 the 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 allow currently the AP operation. Only
native &os; wireless drivers support AP mode.</para>
</note>
<para>Once the wireless networking support is loaded, you can
check if your wireless device supports the host-based access
point mode (also know as hostap mode):</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> list caps</userinput>
ath0=783ed0f<WEP,TKIP,AES,AES_CCM,IBSS,HOSTAP,AHDEMO,TXPMGT,SHSLOT,SHPREAMBLE,MONITOR,TKIPMIC,WPA1,WPA2,BURST,WME></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, WPA2, etc., these informations
are important to know what security protocols could be set
on the Access Point.</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>ath0</replaceable> ssid <replaceable>freebsdap</replaceable> mode 11g mediaopt hostap</userinput> inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</replaceable></screen>
<para>Use again <command>ifconfig</command> to see the status
of the <devicename>ath0</devicename> interface:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
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 <hostap>
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode OPEN privacy OFF txpowmax 38 bmiss 7 protmode CTS burst dtimperiod 1 bintval 100</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 line to
<filename>/etc/rc.conf</filename>:</para>
<programlisting>ifconfig_ath0="ssid <replaceable>freebsdap</replaceable> mode 11g mediaopt hostap inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</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>ath0</replaceable> up scan</userinput>
SSID BSSID CHAN RATE S:N INT CAPS
freebsdap 00:11:95:c3:0d:ac 1 54M 22:1 100 ES</screen>
<para>The client machine found the Access Point and can be
associated with it:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable> ssid <replaceable>freebsdap</replaceable> inet <replaceable>192.168.0.2</replaceable> netmask <replaceable>255.255.255.0</replaceable></userinput>
&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::211:95ff:fed5:4362%ath0 prefixlen 64 scopeid 0x1
inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255
ether 00:11:95:d5:43:62
media: IEEE 802.11 Wireless Ethernet autoselect (OFDM/54Mbps)
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode OPEN privacy OFF txpowmax 36 protmode CTS bintval 100</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=ath0 <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>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> 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 <hostap>
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>ath0</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>ath0</replaceable> ssid <replaceable>freebsdap</replaceable> wepmode on weptxkey 3 wepkey 3:0x3456789012 mode 11g mediaopt hostap \
inet <replaceable>192.168.0.1</replaceable> netmask <replaceable>255.255.255.0</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 (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>ath0</devicename> interface:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</replaceable></userinput>
ath0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
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 <hostap>
status: associated
ssid freebsdap channel 1 bssid 00:11:95:c3:0d:ac
authmode OPEN privacy ON deftxkey 3 wepkey 3:40-bit txpowmax 36 protmode CTS dtimperiod 1 bintval 100</screen>
<para>From another wireless machine, it is possible to initiate
a scan to find the AP:</para>
<screen>&prompt.root; <userinput>ifconfig <replaceable>ath0</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>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 => 0xc80000<assoc,auth,scan></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 these informations. 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>
<note>
<para>The Bluetooth stack has to be started manually on &os; 6.0, and
on &os; 5.X before 5.5. It is done automatically from &man.devd.8;
on &os; 5.5, 6.1 and newer.</para>
<para>Copy
<filename>/usr/share/examples/netgraph/bluetooth/rc.bluetooth</filename>
into some convenient place, like <filename>/etc/rc.bluetooth</filename>.
This 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.bluetooth start ubt0</userinput>
BD_ADDR: 00:02:72:00:d4:1a
Features: 0xff 0xff 0xf 00 00 00 00 00
<3-Slot> <5-Slot> <Encryption> <Slot offset>
<Timing accuracy> <Switch> <Hold mode> <Sniff mode>
<Park mode> <RSSI> <Channel quality> <SCO link>
<HV2 packets> <HV3 packets> <u-law log> <A-law log> <CVSD>
<Paging scheme> <Power control> <Transparent SCO data>
Max. ACL packet size: 192 bytes
Number of ACL packets: 8
Max. SCO packet size: 64 bytes
Number of SCO packets: 8</screen>
</note>
</sect2>
<sect2>
<title>Host Controller Interface (HCI)</title>
<indexterm><primary>HCI</primary></indexterm>
<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>
<sect2>
<title>Logical Link Control and Adaptation Protocol (L2CAP)</title>
<indexterm><primary>L2CAP</primary></indexterm>
<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>
<sect2>
<title>RFCOMM Protocol</title>
<indexterm><primary>RFCOMM</primary></indexterm>
<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>
<sect2>
<title>Pairing of Devices</title>
<indexterm><primary>pairing</primary></indexterm>
<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>On &os; 5.5, 6.1 and newer, 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>
<sect2>
<title>Service Discovery Protocol (SDP)</title>
<indexterm><primary>SDP</primary></indexterm>
<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. On &os; 5.5, 6.1 and newer, 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>On &os; 6.0, and on &os; 5.X before 5.5,
<application>sdpd</application> is not integrated into the system
startup scripts. It has to be started manually with:</para>
<screen>&prompt.root; <userinput>sdpd</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>
<sect2>
<title>OBEX Object Push (OPUSH) Profile</title>
<indexterm><primary>OBEX</primary></indexterm>
<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> get telecom/devinfo.txt devinfo-t39.txt
Success, response: OK, Success (0x20)
obex> put new.vcf
Success, response: OK, Success (0x20)
obex> 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<BROADCAST,SIMPLEX,MULTICAST> 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.</para>
<para>The following table shows the supported operating
modes:</para>
<informaltable frame="none" pgwide="1">
<tgroup cols="3">
<thead>
<row>
<entry>OS Version</entry>
<entry>STP Modes</entry>
<entry>Default Mode</entry>
</row>
</thead>
<tbody>
<row>
<entry>&os; 5.4—&os; 6.2</entry>
<entry>STP</entry>
<entry>STP</entry>
</row>
<row>
<entry>&os; 6.3+</entry>
<entry>RSTP or STP</entry>
<entry>STP</entry>
</row>
<row>
<entry>&os; 7.0+</entry>
<entry>RSTP or STP</entry>
<entry>RSTP</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<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<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> 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<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
port 3 priority 128 path cost 200000 proto rstp
role designated state forwarding
member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
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<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> 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<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
port 4 priority 128 path cost 200000 proto rstp
role root state forwarding
member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP>
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>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.</para>
</listitem>
</varlistentry>
<varlistentry><term>fec</term>
<listitem>
<para>Supports Cisco EtherChannel. This 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>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>Supports 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. 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>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>roundrobin</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 will violate 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 interfaces to the channel group.</para>
<screen>interface FastEthernet0/1
channel-group 1 mode active
channel-protocol lacp
!
interface FastEthernet0/2
channel-group 1 mode active
channel-protocol lacp
!</screen>
<para>On the &os; machine create the lagg interface.</para>
<screen>&prompt.root; <userinput>ifconfig lagg0 create</userinput>
&prompt.root; <userinput>ifconfig lagg0 up laggproto lacp laggport fxp0 laggport fxp1</userinput></screen>
<para>View the interface status from ifconfig; 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<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=8<VLAN_MTU>
ether 00:05:5d:71:8d:b8
media: Ethernet autoselect
status: active
laggproto lacp
laggport: fxp1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>
laggport: fxp0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING></screen>
<para>The switch will show which ports are active. For more detail use
<userinput>show lacp neighbor detail</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>
</example>
<example id="networking-lagg-failover">
<title>Failover mode</title>
<para>Failover mode can be used to switch over to another interface if
the link is lost on the master.</para>
<screen>&prompt.root; <userinput>ifconfig lagg0 create</userinput>
&prompt.root; <userinput>ifconfig lagg0 up laggproto failover laggport fxp0 laggport fxp1</userinput></screen>
<screen>lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=8<VLAN_MTU>
ether 00:05:5d:71:8d:b8
media: Ethernet autoselect
status: active
laggproto failover
laggport: fxp1 flags=0<>
laggport: fxp0 flags=5<MASTER,ACTIVE></screen>
<para>Traffic will be transmitted and received on
<devicename>fxp0</devicename>. If the link is lost on
<devicename>fxp0</devicename> then <devicename>fxp1</devicename> will
become the active link. If the link is restored on the master
interface then it will once again become the active link.</para>
</example>
</sect2>
</sect1>
<sect1 id="network-diskless">
<sect1info>
<authorgroup>
<author>
<firstname>Jean-François</firstname>
<surname>Dockès</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
3.0</application> is not part of the base
system. You will first need to install the
<filename role="package">net/isc-dhcp3-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 && make buildkernel
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-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 <filename>/usr/share/examples/isdn/</filename>
directory on your FreeBSD system or 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 Kbs, even though you have a 128 Kbs connection.
To fully utilize the 128 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 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—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-natdkernconfiguration">
<title>Configuration</title>
<indexterm>
<primary>kernel</primary>
<secondary>configuration</secondary>
</indexterm>
<para>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>
<para>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: <Printer> 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<POINTOPOINT,SIMPLEX,MULTICAST> 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 <-----> 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</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<UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 10.0.0.1 --> 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> </entry>
</row>
<row>
<entry><hostid role="ip6addr">ff::</hostid></entry>
<entry>8 bits</entry>
<entry>multicast</entry>
<entry> </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<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> 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>Getting an IPv6 network from your upstream provider. Talk to your
Internet provider for instructions.</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 all you need to add is:</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:</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:</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 Access Redundancy Protocol (CARP)</title>
<indexterm><primary>CARP</primary></indexterm>
<indexterm><primary>Common Access Redundancy Protocol</primary></indexterm>
<para>The Common Access 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 with the following option:</para>
<programlisting>device carp</programlisting>
<para><acronym>CARP</acronym> functionality should now be available
and may be tuned via several <command>sysctl</command>
<acronym>OID</acronym>s. Devices themselves may be loaded 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 testpast 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
<quote>nudge</quote> the interface. 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>