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     The FreeBSD Documentation Project

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<chapter id="advanced-networking">
  <title>Advanced Networking</title>

  <sect1 id="advanced-networking-synopsis">
    <title>Synopsis</title>

    <para>This chapter will cover a number of advanced networking
      topics.</para>

    <para>After reading this chapter, you will know:</para>

    <itemizedlist>
      <listitem>
	<para>The basics of gateways and routes.</para>
      </listitem>

      <listitem>
	<para>How to set up IEEE 802.11 and &bluetooth; devices.</para>
      </listitem>

      <listitem>
	<para>How to make FreeBSD act as a bridge.</para>
      </listitem>

      <listitem>
	<para>How to set up network booting on a diskless machine.</para>
      </listitem>

      <listitem>
	<para>How to set up network address translation.</para>
      </listitem>

      <listitem>
	<para>How to connect two computers via PLIP.</para>
      </listitem>

      <listitem>
	<para>How to set up IPv6 on a FreeBSD machine.</para>
      </listitem>

      <listitem>
	<para>How to configure ATM under &os;&nbsp;5.X.</para>
      </listitem>
    </itemizedlist>

    <para>Before reading this chapter, you should:</para>

    <itemizedlist>
      <listitem>
	<para>Understand the basics of the <filename>/etc/rc</filename> scripts.</para>
      </listitem>

      <listitem>
	<para>Be familiar with basic network terminology.</para>
      </listitem>

      <listitem>
        <para>Know how to configure and install a new FreeBSD kernel
          (<xref linkend="kernelconfig">).</para>
      </listitem>

      <listitem>
      <para>Know how to install additional third-party
        software (<xref linkend="ports">).</para>
      </listitem>

    </itemizedlist>
  </sect1>

  <sect1 id="network-routing">
    <sect1info>
      <authorgroup>
        <author>
          <firstname>Coranth</firstname>
      	  <surname>Gryphon</surname>
	  <contrib>Contributed by </contrib>
        </author>
      </authorgroup>
    </sect1info>
    <title>Gateways and Routes</title>

    <indexterm><primary>routing</primary></indexterm>
    <indexterm><primary>gateway</primary></indexterm>
    <indexterm><primary>subnet</primary></indexterm>
    <para>For one machine to be able to find another over a network,
      there must be a mechanism in place to describe how to get from
      one to the other.  This is called
      <firstterm>routing</firstterm>.  A <quote>route</quote> is a
      defined pair of addresses: a <quote>destination</quote> and a
      <quote>gateway</quote>.  The pair indicates that if you are
      trying to get to this <emphasis>destination</emphasis>,
      communicate through this <emphasis>gateway</emphasis>.  There
      are three types of destinations: individual hosts, subnets, and
      <quote>default</quote>.  The <quote>default route</quote> is
      used if none of the other routes apply.  We will talk a little
      bit more about default routes later on.  There are also three
      types of gateways: individual hosts, interfaces (also called
      <quote>links</quote>), and Ethernet hardware addresses (MAC
      addresses).
    </para>

    <sect2>
      <title>An Example</title>

      <para>To illustrate different aspects of routing, we will use the
	following example from <command>netstat</command>:</para>

      <screen>&prompt.user; <userinput>netstat -r</userinput>
Routing tables

Destination      Gateway            Flags     Refs     Use     Netif Expire

default          outside-gw         UGSc       37      418      ppp0
localhost        localhost          UH          0      181       lo0
test0            0:e0:b5:36:cf:4f   UHLW        5    63288       ed0     77
10.20.30.255     link#1             UHLW        1     2421
example.com      link#1             UC          0        0
host1            0:e0:a8:37:8:1e    UHLW        3     4601       lo0
host2            0:e0:a8:37:8:1e    UHLW        0        5       lo0 =>
host2.example.com link#1             UC          0        0
224              link#1             UC          0        0</screen>

      <indexterm><primary>default route</primary></indexterm>
      <para>The first two lines specify the default route (which we
	will cover in the <link linkend="network-routing-default">next
	  section</link>) and the <hostid>localhost</hostid> route.</para>

      <indexterm><primary>loopback device</primary></indexterm>
      <para>The interface (<literal>Netif</literal> column) that this
	routing table specifies to use for
	<literal>localhost</literal> is <devicename>lo0</devicename>,
	also known as the loopback device.  This says to keep all
	traffic for this destination internal, rather than sending it
	out over the LAN, since it will only end up back where it
	started.</para>

      <indexterm>
        <primary>Ethernet</primary>
        <secondary>MAC address</secondary>
      </indexterm>
      <para>The next thing that stands out are the addresses beginning
	with <hostid role="mac">0:e0:</hostid>.  These are Ethernet
	hardware addresses, which are also known as MAC addresses.
	FreeBSD will automatically identify any hosts
	(<hostid>test0</hostid> in the example) on the local Ethernet
	and add a route for that host, directly to it over the
	Ethernet interface, <devicename>ed0</devicename>.  There is
	also a timeout (<literal>Expire</literal> column) associated
	with this type of route, which is used if we fail to hear from
	the host in a specific amount of time.  When this happens, the
	route to this host will be automatically deleted.  These hosts
	are identified using a mechanism known as RIP (Routing
	Information Protocol), which figures out routes to local hosts
	based upon a shortest path determination.</para>

      <indexterm><primary>subnet</primary></indexterm>
      <para>FreeBSD will also add subnet routes for the local subnet (<hostid
	  role="ipaddr">10.20.30.255</hostid> is the broadcast address for the
	subnet <hostid role="ipaddr">10.20.30</hostid>, and <hostid
	  role="domainname">example.com</hostid> is the domain name associated
	with that subnet).  The designation <literal>link#1</literal> refers
	to the first Ethernet card in the machine.  You will notice no
	additional interface is specified for those.</para>

      <para>Both of these groups (local network hosts and local subnets) have
	their routes automatically configured by a daemon called
	<application>routed</application>.  If this is not run, then only
	routes which are statically defined (i.e. entered explicitly) will
	exist.</para>

      <para>The <literal>host1</literal> line refers to our host, which it
	knows by Ethernet address.  Since we are the sending host, FreeBSD
	knows to use the loopback interface (<devicename>lo0</devicename>)
	rather than sending it out over the Ethernet interface.</para>

      <para>The two <literal>host2</literal> lines are an example of
	what happens when we use an &man.ifconfig.8; alias (see the
	section on Ethernet for reasons why we would do this).  The
	<literal>=&gt;</literal> symbol after the
	<devicename>lo0</devicename> interface says that not only are
	we using the loopback (since this address also refers to the
	local host), but specifically it is an alias.  Such routes
	only show up on the host that supports the alias; all other
	hosts on the local network will simply have a
	<literal>link#1</literal> line for such routes.</para>

      <para>The final line (destination subnet <hostid role="ipaddr">224</hostid>) deals
	with multicasting, which will be covered in another section.</para>

      <para>Finally, various attributes of each route can be seen in
	the <literal>Flags</literal> column.  Below is a short table
	of some of these flags and their meanings:</para>

      <informaltable frame="none" pgwide="1">
	<tgroup cols="2">
	  <colspec colwidth="1*">
	  <colspec colwidth="4*">

	  <tbody>
	    <row>
	      <entry>U</entry>
	      <entry>Up: The route is active.</entry>
	    </row>

	    <row>
	      <entry>H</entry>
	      <entry>Host: The route destination is a single host.</entry>
	    </row>

	    <row>
	      <entry>G</entry>
	      <entry>Gateway: Send anything for this destination on to this
		remote system, which will figure out from there where to send
		it.</entry>
	    </row>

	    <row>
	      <entry>S</entry>
	      <entry>Static: This route was configured manually, not
		automatically generated by the system.</entry>
	    </row>

	    <row>
	      <entry>C</entry>
	      <entry>Clone: Generates a new route based upon this route for
		machines we connect to.  This type of route is normally used
		for local networks.</entry>
	    </row>

	    <row>
	      <entry>W</entry>
	      <entry>WasCloned: Indicated a route that was auto-configured
		based upon a local area network (Clone) route.</entry>
	    </row>

	    <row>
	      <entry>L</entry>
	      <entry>Link: Route involves references to Ethernet
		hardware.</entry>
	    </row>
	  </tbody>
	</tgroup>
      </informaltable>
    </sect2>

    <sect2 id="network-routing-default">
      <title>Default Routes</title>

      <indexterm><primary>default route</primary></indexterm>
      <para>When the local system needs to make a connection to a remote host,
	it checks the routing table to determine if a known path exists.  If
	the remote host falls into a subnet that we know how to reach (Cloned
	routes), then the system checks to see if it can connect along that
	interface.</para>

      <para>If all known paths fail, the system has one last option: the
	<quote>default</quote> route.  This route is a special type of gateway
	route (usually the only one present in the system), and is always
	marked with a <literal>c</literal> in the flags field.  For hosts on a
	local area network, this gateway is set to whatever machine has a
	direct connection to the outside world (whether via PPP link,
	DSL, cable modem, T1, or another network interface).</para>

      <para>If you are configuring the default route for a machine which
	itself is functioning as the gateway to the outside world, then the
	default route will be the gateway machine at your Internet Service
	Provider's (ISP) site.</para>

      <para>Let us look at an example of default routes.  This is a common
	configuration:</para>

      <mediaobject>
	<imageobject>
	  <imagedata fileref="advanced-networking/net-routing">
	</imageobject>

	<textobject>
	  <literallayout class="monospaced">
[Local2]  &lt;--ether--&gt;  [Local1]  &lt;--PPP--&gt; [ISP-Serv]  &lt;--ether--&gt;  [T1-GW]
      </literallayout>
	</textobject>
      </mediaobject>

      <para>The hosts <hostid>Local1</hostid> and
	<hostid>Local2</hostid> are at your site.
	<hostid>Local1</hostid> is connected to an ISP via a dial up
	PPP connection.  This PPP server computer is connected through
	a local area network to another gateway computer through an
	external interface to the ISPs Internet feed.</para>

      <para>The default routes for each of your machines will be:</para>

      <informaltable frame="none" pgwide="1">
	<tgroup cols="3">
	  <thead>
	    <row>
	      <entry>Host</entry>
	      <entry>Default Gateway</entry>
	      <entry>Interface</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry>Local2</entry>
	      <entry>Local1</entry>
	      <entry>Ethernet</entry>
	    </row>

	    <row>
	      <entry>Local1</entry>
	      <entry>T1-GW</entry>
	      <entry>PPP</entry>
	    </row>
	  </tbody>
	</tgroup>
      </informaltable>

      <para>A common question is <quote>Why (or how) would we set
	the <hostid>T1-GW</hostid> to be the default gateway for
	<hostid>Local1</hostid>, rather than the ISP server it is
	connected to?</quote>.</para>

      <para>Remember, since the PPP interface is using an address on the ISP's
	local network for your side of the connection, routes for any other
	machines on the ISP's local network will be automatically generated.
	Hence, you will already know how to reach the <hostid>T1-GW</hostid>
	machine, so there is no need for the intermediate step
	of sending traffic to the ISP server.</para>

      <para>It is common to use the address <hostid
	  role="ipaddr">X.X.X.1</hostid> as the gateway address for your local
	network.  So (using the same example), if your local class-C address
	space was <hostid role="ipaddr">10.20.30</hostid> and your ISP was
	using <hostid role="ipaddr">10.9.9</hostid> then the default routes
	would be:</para>

      <informaltable frame="none" pgwide="1">
	<tgroup cols="2">
	  <thead>
	    <row>
	      <entry>Host</entry>
	      <entry>Default Route</entry>
	    </row>
	  </thead>
	  <tbody>
	    <row>
	      <entry>Local2 (10.20.30.2)</entry>
	      <entry>Local1 (10.20.30.1)</entry>
	    </row>
	    <row>
	      <entry>Local1 (10.20.30.1, 10.9.9.30)</entry>
	      <entry>T1-GW (10.9.9.1)</entry>
	    </row>
	  </tbody>
	</tgroup>
      </informaltable>

      <para>You can easily define the default route via the
	<filename>/etc/rc.conf</filename> file.  In our example, on the
	<hostid>Local2</hostid> machine, we added the following line
	in <filename>/etc/rc.conf</filename>:</para>

      <programlisting>defaultrouter="10.20.30.1"</programlisting>

      <para>It is also possible to do it directly from the command
	line with the &man.route.8; command:</para>

      <screen>&prompt.root; <userinput>route add default 10.20.30.1</userinput></screen>

      <para>For more information on manual manipulation of network
	routing tables, consult &man.route.8; manual page.</para>
    </sect2>

    <sect2>
      <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>
          <firstname>Eric</firstname>
          <surname>Anderson</surname>
          <contrib>Written by </contrib>
        </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>Introduction</title>
      <para>It can be very useful to be able to use a computer without the
      annoyance of having a network cable attached at all times.  FreeBSD can
      be used as a wireless client, and even as a wireless <quote>access
      point</quote>.</para>
   </sect2>

   <sect2>
     <title>Wireless Modes of Operation</title>
     <para>There are two different ways to configure 802.11 wireless devices:
      BSS and IBSS.</para>

     <sect3>
       <title>BSS Mode</title>
       <para>BSS mode is the mode that typically is used.  BSS mode is
        also called infrastructure mode.  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.</para>

       <para>Wireless clients connect to these wireless access
        points. The IEEE 802.11 standard defines the protocol that
        wireless networks use to connect.  A wireless client can be
        tied to a specific network, when a SSID is set.  A wireless
        client can also attach to any network by not explicitly
        setting a SSID.</para>
     </sect3>

     <sect3>
       <title>IBSS Mode</title>
       <para>IBSS mode, also called ad-hoc mode, is designed for point
         to point connections.  There are actually two types of ad-hoc
         mode.  One is IBSS mode, also called ad-hoc or IEEE ad-hoc
         mode.  This mode is defined by the IEEE 802.11 standards.
         The second is called demo ad-hoc mode or Lucent ad-hoc mode
         (and sometimes, confusingly, ad-hoc mode).  This is the old,
         pre-802.11 ad-hoc mode and should only be used for legacy
	 installations.  We will not cover either of the ad-hoc modes
         further.</para>
     </sect3>
   </sect2>

   <sect2>
     <title>Infrastructure Mode</title>
     <sect3>
       <title>Access Points</title>

       <para>Access points are wireless networking devices that allow
        one or more wireless clients to use the device as a central
        hub.  When using an access point, all clients communicate
        through the access point.  Multiple access points are often
        used to cover a complete area such as a house, business, or
        park with a wireless network.</para>

       <para>Access points typically have multiple network
       connections: the wireless card, and one or more wired Ethernet
       adapters for connection to the rest of the network.
       </para>

       <para>Access points can either be purchased prebuilt, or you
        can build your own with FreeBSD and a supported wireless card.
        Several vendors make wireless access points and wireless cards
        with various features.</para>
     </sect3>

     <sect3>
       <title>Building a FreeBSD Access Point</title>
       <indexterm><primary>wireless networking</primary>
         <secondary>access point</secondary>
       </indexterm>

       <sect4><title>Requirements</title>

         <para>In order to set up a wireless access point with
          FreeBSD, you need to have a compatible wireless card.
          Currently, only cards with the Prism chipset are
          supported. You will also need a wired network card that is
          supported by FreeBSD (this should not be difficult to find,
          FreeBSD supports a lot of different devices).  For this
          guide, we will assume you want to &man.bridge.4; all traffic
          between the wireless device and the network attached to the
          wired network card.</para>

	 <para>The hostap functionality that FreeBSD uses to implement
           the access point works best with certain versions of
           firmware.  Prism 2 cards should use firmware version 1.3.4
           or newer.  Prism 2.5 and Prism 3 cards should use firmware
           1.4.9.  Older versions of the firmware way or may not
           function correctly.  At this time, the only way to update
           cards is with &windows; firmware update utilities available
           from your card's manufacturer.</para>
       </sect4>

       <sect4>
         <title>Setting It Up</title>
         <para>First, make sure your system can see the wireless card:</para>
         <screen>&prompt.root; <userinput>ifconfig -a</userinput>
wi0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
        inet6 fe80::202:2dff:fe2d:c938%wi0 prefixlen 64 scopeid 0x7
        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255
        ether 00:09:2d:2d:c9:50
        media: IEEE 802.11 Wireless Ethernet autoselect (DS/2Mbps)
        status: no carrier
        ssid ""
        stationname "FreeBSD Wireless node"
        channel 10 authmode OPEN powersavemode OFF powersavesleep 100
        wepmode OFF weptxkey 1</screen>

         <para>Do not worry about the details now, just make sure it shows you
          something to indicate you have a wireless card installed.
	  If you have trouble seeing the wireless interface, and you
	  are using a PC Card, you may want to check out
	  &man.pccardc.8; and &man.pccardd.8; manual pages for more
	  information.</para>

         <para>Next, you will need to load a module in order to get
          the bridging part of FreeBSD ready for the access point.
          To load the &man.bridge.4; module, simply run the
          following command:</para>

         <screen>&prompt.root; <userinput>kldload bridge</userinput></screen>

         <para>It should not have produced any errors when loading the
          module.  If it did, you may need to compile the
          &man.bridge.4; code into your kernel.  The <link
          linkend="network-bridging">Bridging</link> section of this handbook
          should be able to help you accomplish that task.</para>

         <para>Now that you have the bridging stuff done, we need to
          tell the FreeBSD kernel which interfaces to bridge together.
          We do that by using &man.sysctl.8;:</para>

	<screen>&prompt.root; <userinput>sysctl net.link.ether.bridge.enable=1</userinput>
&prompt.root; <userinput>sysctl net.link.ether.bridge.config="wi0,xl0"</userinput>
&prompt.root; <userinput>sysctl net.inet.ip.forwarding=1</userinput></screen>

	<para>On &os; versions earlier than 5.2, you
	  need to use the following options instead:</para>

	<screen>&prompt.root; <userinput>sysctl net.link.ether.bridge=1</userinput>
&prompt.root; <userinput>sysctl net.link.ether.bridge_cfg="wi0,xl0"</userinput>
&prompt.root; <userinput>sysctl net.inet.ip.forwarding=1</userinput></screen>

         <para>Now it is time for the wireless card setup.
         The following command will set the card into an access point:</para>

         <screen>
&prompt.root; <userinput>ifconfig wi0 ssid <replaceable>my_net</replaceable> channel 11 media DS/11Mbps mediaopt hostap up stationname "<replaceable>FreeBSD AP</replaceable>"</userinput>
         </screen>

         <para>The &man.ifconfig.8; line brings the
	  <devicename>wi0</devicename> interface up, sets its SSID to
	  <replaceable>my_net</replaceable>, and sets the station name to
	  <replaceable>FreeBSD AP</replaceable>.  The <option>media
	  DS/11Mbps</option> sets the card into 11Mbps mode and is
	  needed for any <option>mediaopt</option> to take effect.
	  The <option>mediaopt hostap</option> option places the
	  interface into access point mode.  The <option>channel
	  11</option> option sets the 802.11b channel to use.  The
	  &man.wicontrol.8; manual page has valid channel options for
	  your regulatory domain.
         </para>

         <para>Now you should have a complete functioning access point
          up and running.  You are encouraged to read
          &man.wicontrol.8;, &man.ifconfig.8;, and &man.wi.4; for
          further information.
         </para>

         <para>It is also suggested that you read the section on encryption that follows.</para>
       </sect4>

       <sect4>
         <title>Status Information</title>
	 <para>Once the access point is configured and operational,
	   operators will want to see the clients that are associated
	   with the access point.  At any time, the operator may type:</para>

         <screen>&prompt.root; <userinput>wicontrol -l</userinput>
1 station:
00:09:b7:7b:9d:16  asid=04c0, flags=3&lt;ASSOC,AUTH&gt;, caps=1&lt;ESS&gt;, rates=f&lt;1M,2M,5.5M,11M&gt;, sig=38/15
</screen>

         <para>This shows that there is one station associated, along
           with its parameters.  The signal indicated should be used
           as a relative indication of strength only.  Its
           translation to dBm or other units varies between different
           firmware revisions.</para>
       </sect4>
     </sect3>

     <sect3>
       <title>Clients</title>

       <para>A wireless client is a system that accesses an access
       point or another client directly. </para>

       <para>Typically, wireless clients only have one network device,
       the wireless networking card.</para>

       <para>There are a few different ways to configure a wireless
        client.  These are based on the different wireless modes,
        generally BSS (infrastructure mode, which requires an access
        point), and IBSS (ad-hoc, or peer-to-peer mode).  In our
        example, we will use the most popular of the two, BSS mode, to
        talk to an access point.</para>

       <sect4>
       <title>Requirements</title>
       <para>There is only one real requirement for setting up FreeBSD as a wireless client.
        You will need a wireless card that is supported by FreeBSD.</para>
       </sect4>

       <sect4>
       <title>Setting Up a Wireless FreeBSD Client</title>

       <para>You will need to know a few things about the wireless
        network you are joining before you start.  In this example, we
        are joining a network that has a name of
        <replaceable>my_net</replaceable>, and encryption turned off.</para>

       <note><para>In this example, we are not using encryption, which
        is a dangerous situation.  In the next section, you will learn
        how to turn on encryption, why it is important to do so,
        and why some encryption technologies still do not completely
        protect you.</para></note>

       <para>Make sure your card is recognized by FreeBSD:</para>

       <screen>&prompt.root; <userinput>ifconfig -a</userinput>
wi0: flags=8843&lt;UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
        inet6 fe80::202:2dff:fe2d:c938%wi0 prefixlen 64 scopeid 0x7
        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255
        ether 00:09:2d:2d:c9:50
        media: IEEE 802.11 Wireless Ethernet autoselect (DS/2Mbps)
        status: no carrier
        ssid ""
        stationname "FreeBSD Wireless node"
        channel 10 authmode OPEN powersavemode OFF powersavesleep 100
        wepmode OFF weptxkey 1</screen>

       <para>Now, we can set the card to the correct settings for our
       network:</para>

       <screen>&prompt.root; <userinput>ifconfig wi0 inet <replaceable>192.168.0.20</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>my_net</replaceable></userinput></screen>

       <para>Replace <hostid role="ipaddr">192.168.0.20</hostid> and
        <hostid role="netmask">255.255.255.0</hostid> with a valid IP
        address and netmask on your wired network.  Remember, our
        access point is bridging the data between the wireless
        network, and the wired network, so it will appear to the other
        devices on your network that you are on the wired network just
        as they are.</para>

       <para>Once you have done that, you should be able to ping hosts
        on the wired network just as if you were connected using a
        standard wired connection.</para>

       <para>If you are experiencing problems with your wireless
        connection, check to make sure that you are associated
        (connected) to the access point:</para>

       <screen>&prompt.root; <userinput>ifconfig wi0</userinput></screen>

       <para>should return some information, and you should see:</para>
       <screen>status: associated</screen>

       <para>If it does not show <literal>associated</literal>, then you may be out of
       range of the access point, have encryption on, or
       possibly have a configuration problem.</para>

       </sect4>
     </sect3>

     <sect3>
      <title>Encryption</title>
      <indexterm>
        <primary>wireless networking</primary>
        <secondary>encryption</secondary>
      </indexterm>

      <para>Encryption on a wireless network is important because you
       no longer have the ability to keep the network contained in a
       well protected area.  Your wireless data will be broadcast
       across your entire neighborhood, so anyone who cares to read it
       can.  This is where encryption comes in.  By encrypting the
       data that is sent over the airwaves, you make it much more
       difficult for any interested party to grab your data right out
       of the air. </para>

     <para>The two most common ways to encrypt the data between your
      client and the access point are WEP, and &man.ipsec.4;.</para>

     <sect4>
     <title>WEP</title>
      <indexterm><primary>WEP</primary></indexterm>

      <para>WEP is an abbreviation for Wired Equivalency Protocol.
       WEP is an attempt to make wireless networks as safe and secure
       as a wired network.  Unfortunately, it has been cracked, and is
       fairly trivial to break.  This also means it is not something
       to rely on when it comes to encrypting sensitive data.  </para>

      <para>It is better than nothing, so use the following to turn on
       WEP on your new FreeBSD access point:</para>

      <screen>&prompt.root; <userinput>ifconfig wi0 inet up ssid <replaceable>my_net</replaceable> wepmode on wepkey <replaceable>0x1234567890</replaceable> media DS/11Mbps mediaopt hostap</userinput></screen>

      <para>And you can turn on WEP on a client with this command:</para>

      <screen>&prompt.root; <userinput>ifconfig wi0 inet <replaceable>192.168.0.20</replaceable> netmask <replaceable>255.255.255.0</replaceable> ssid <replaceable>my_net</replaceable> wepmode on wepkey <replaceable>0x1234567890</replaceable></userinput></screen>

      <para>Note that you should replace the <replaceable>0x1234567890</replaceable> with a more unique key.</para>

     </sect4>

     <sect4>
     <title>IPsec</title>

     <para>&man.ipsec.4; is a much more robust and powerful tool for
       encrypting data across a network.  This is definitely the
       preferred way to encrypt data over a wireless network.  You can
       read more about &man.ipsec.4; security and how to implement it
       in the <link linkend="ipsec">IPsec</link> section of this
       handbook.</para>
     </sect4>
    </sect3>

    <sect3>
    <title>Tools</title>

    <para>There are a small number of tools available for use in
      debugging and setting up your wireless network, and here we will
      attempt to describe some of them and what they do.</para>

    <sect4>
    <title>The <application>bsd-airtools</application> Package</title>

    <para>The <application>bsd-airtools</application> package is a
      complete toolset that includes wireless auditing tools for WEP
      key cracking, access point detection, etc.</para>

    <para>The <application>bsd-airtools</application> utilities can be
      installed from the <filename
      role="package">net/bsd-airtools</filename> port.  Information on
      installing ports can be found in <xref linkend="ports"> of this
      handbook.</para>

    <para>The program <command>dstumbler</command> is the packaged
      tool that allows for access point discovery and signal to noise
      ratio graphing.  If you are having a hard time getting your
      access point up and running, <command>dstumbler</command> may
      help you get started.</para>

    <para>To test your wireless network security, you may choose to
      use <quote>dweputils</quote> (<command>dwepcrack</command>,
      <command>dwepdump</command> and <command>dwepkeygen</command>)
      to help you determine if WEP is the right solution to your
      wireless security needs.</para>

    </sect4>

    <sect4>
    <title>The <command>wicontrol</command>, <command>ancontrol</command> and <command>raycontrol</command> Utilities</title>

    <para>These are the tools you can use to control how your wireless
      card behaves on the wireless network.  In the examples above, we
      have chosen to use &man.wicontrol.8;, since our wireless card is
      a <devicename>wi0</devicename> interface.  If you had a Cisco
      wireless device, it would come up as
      <devicename>an0</devicename>, and therefore you would use
      &man.ancontrol.8;.</para>

    </sect4>

    <sect4>
    <title>The <command>ifconfig</command> Command</title>
    <indexterm><primary>ifconfig</primary></indexterm>

    <para>The &man.ifconfig.8; command can be used to do many of the same options
      as &man.wicontrol.8;, however it does lack a few options.  Check
      &man.ifconfig.8; for command line parameters and options.</para>

    </sect4>

    </sect3>

    <sect3>
    <title>Supported Cards</title>
    <sect4>
    <title>Access Points</title>

    <para>The only cards that are currently supported for BSS (as an
      access point) mode are devices based on the Prism 2, 2.5, or 3
      chipsets. For a complete list, look at &man.wi.4;.</para>

    </sect4>

    <sect4>
    <title>802.11b Clients</title>

    <para>Almost all 802.11b wireless cards are currently supported
      under FreeBSD.  Most cards based on Prism, Spectrum24, Hermes,
      Aironet, and Raylink will work as a wireless network card in
      IBSS (ad-hoc, peer-to-peer, and BSS) mode.</para>

    </sect4>

    <sect4>
    <title>802.11a & 802.11g Clients</title>

    <para>The &man.ath.4; device driver supports 802.11a and 802.11g. 
      If your card is based on an Atheros chipset, you may
      be able to use this driver.</para>

    <para>Unfortunately, there are still many vendors that do not
      provide schematics for their drivers to the open source
      community because they regard such information as trade
      secrets. Consequently, the developers of FreeBSD and other
      operating systems are left two choices: develop the drivers by
      a long and pain-staking process of reverse engineering or using
      the existing driver binaries available for the
      &microsoft.windows; platforms. Most developers, including those
      involved with FreeBSD, have taken the latter approach.</para>

    <para>Thanks to the contributions of Bill Paul (wpaul), as of
      FreeBSD&nbsp;5.3-RELEASE there is <quote>native</quote>
      support for the Network Driver Interface Specification
      (NDIS). The FreeBSD NDISulator (otherwise known as Project Evil)
      takes a &windows; driver binary and basically tricks it into
      thinking it is running on &windows;.  This feature is still
      relatively new, but most test cases seem to work
      adequately.</para>

    <indexterm><primary>NDIS</primary></indexterm>
    <indexterm><primary>NDISulator</primary></indexterm>
    <indexterm><primary>&windows drivers</primary></indexterm>
    <indexterm><primary>Microsoft Windows</primary></indexterm>
    <indexterm><primary>Microsoft Windows</primary>
	<secondary>device drivers</secondary></indexterm>
    <indexterm><primary>KLD (kernel loadable object)</primary></indexterm>
<!-- We should probably omit the expanded name, and add a <see> entry
for it.  Whatever is done must also be done to the same indexterm in
linuxemu/chapter.sgml -->

    <para>In order to use the NDISulator, you need three things:</para>

    <orderedlist>
     <listitem>
      <para>Kernel sources</para>
     </listitem>
     <listitem>
      <para>&windowsxp; driver binary 
        (<filename>.SYS</filename> extension)</para>
     </listitem>
     <listitem>
      <para>&windowsxp; driver configuration file 
        (<filename>.INF</filename> extension)</para>
     </listitem>
    </orderedlist>
 
      <para>You may need to compile the &man.ndis.4; mini port driver 
        wrapper module. As <username>root</username>:</para> 

    <screen>&prompt.root; <userinput>cd /usr/src/sys/modules/ndis</userinput>
&prompt.root; <userinput>make && make install</userinput></screen>

    <para>Locate the files for your specific card. Generally, they can
      be found on the included CDs or at the vendors' websites. In the
      following examples, we will use
      <filename>W32DRIVER.SYS</filename> and
      <filename>W32DRIVER.INF</filename>.</para>

    <para>The next step is to compile the driver binary into a
      loadable kernel module. To accomplish this, as
      <username>root</username>, go into the
      <filename>if_ndis</filename> module directory and copy the
      &windows; driver files into it:</para>

   <screen>&prompt.root; <userinput>cd /usr/src/sys/modules/if_ndis</userinput>
&prompt.root; <userinput>cp <replaceable>/path/to/driver/W32DRIVER.SYS</replaceable> ./</userinput>
&prompt.root; <userinput>cp <replaceable>/path/to/driver/W32DRIVER.INF</replaceable> ./</userinput></screen>

    <para>We will now use the <command>ndiscvt</command> utility to
      create the driver definition header
      <filename>ndis_driver_data.h</filename> to build the
      module:</para>

    <screen>&prompt.root; <userinput>ndiscvt -i <replaceable>W32DRIVER.INF</replaceable> -s <replaceable>W32DRIVER.SYS</replaceable> -o ndis_driver_data.h</userinput></screen>

    <para>The <option>-i</option> and <option>-s</option> options specify 
      the configuration and binary files, respectively. We use the 
      <option>-o ndis_driver_data.h</option> option because the 
      <filename>Makefile</filename> will be looking for this file when it 
      comes time to build the module. </para>

    <note>
      <para>Some &windows; drivers require additional files to operate. You
        may include them with <command>ndiscvt</command> by using the 
        <option>-f</option> option. Consult the &man.ndiscvt.8; manual page 
        for more information.</para>
    </note>

    <para>Finally, we can build and install the driver module:</para>

    <screen>&prompt.root; <userinput>make && make install</userinput></screen>

    <para>To use the driver, you must load the appropriate modules:</para>

    <screen>&prompt.root; <userinput>kldload ndis</userinput>
&prompt.root; <userinput>kldload if_ndis</userinput></screen>

    <para>The first command loads the NDIS miniport driver wrapper,
      the second loads the actual network interface.  Check
      &man.dmesg.8; to see if there were any errors loading.  If all
      went well, you should get output resembling the
      following:</para>

    <screen>ndis0: &lt;Wireless-G PCI Adapter&gt; mem 0xf4100000-0xf4101fff irq 3 at device 8.0 on pci1
ndis0: NDIS API version: 5.0
ndis0: Ethernet address: 0a:b1:2c:d3:4e:f5
ndis0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
ndis0: 11g rates: 6Mbps 9Mbps 12Mbps 18Mbps 36Mbps 48Mbps 54Mbps</screen>
  
    <para>From here you can treat the <devicename>ndis0</devicename> device 
      like any other wireless device (e.g. <devicename>wi0</devicename>) and 
      consult the earlier sections of this chapter.</para>
    
    </sect4>

    </sect3>
   </sect2>
  </sect1>

  <sect1 id="network-bluetooth">
    <sect1info>
      <authorgroup>
        <author>
          <firstname>Pav</firstname>
          <surname>Lucistnik</surname>
          <contrib>Written by </contrib>
          <affiliation>
            <address><email>pav@oook.cz</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. Bluetooth support is available in &os; 5.0 and newer
        systems.</para>
    </sect2>

    <sect2>
      <title>Plugging in the Device</title>
      <para>By default Bluetooth device drivers are available as kernel modules.
        Before attaching a device, you will need to load the driver into the
        kernel:</para>

      <screen>&prompt.root; <userinput>kldload ng_ubt</userinput></screen>

      <para>If the Bluetooth device is present in the system during system
        startup, load the module from
        <filename>/boot/loader.conf</filename>:</para>

      <programlisting>ng_ubt_load="YES"</programlisting>

      <para>Plug in your USB dongle. The output similar to the following will
        appear on the console (or in syslog):</para>

      <screen>ubt0: vendor 0x0a12 product 0x0001, rev 1.10/5.25, addr 2
ubt0: Interface 0 endpoints: interrupt=0x81, bulk-in=0x82, bulk-out=0x2
ubt0: Interface 1 (alt.config 5) endpoints: isoc-in=0x83, isoc-out=0x3,
      wMaxPacketSize=49, nframes=6, buffer size=294</screen>

      <para>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
&lt;3-Slot&gt; &lt;5-Slot&gt; &lt;Encryption&gt; &lt;Slot offset&gt;
&lt;Timing accuracy&gt; &lt;Switch&gt; &lt;Hold mode&gt; &lt;Sniff mode&gt;
&lt;Park mode&gt; &lt;RSSI&gt; &lt;Channel quality&gt; &lt;SCO link&gt;
&lt;HV2 packets&gt; &lt;HV3 packets&gt; &lt;u-law log&gt; &lt;A-law log&gt; &lt;CVSD&gt;
&lt;Paging scheme&gt; &lt;Power control&gt; &lt;Transparent SCO data&gt;
Max. ACL packet size: 192 bytes
Number of ACL packets: 8
Max. SCO packet size: 64 bytes
Number of SCO packets: 8</screen>

    </sect2>

    <indexterm><primary>HCI</primary></indexterm>
    <sect2>
      <title>Host Controller Interface (HCI)</title>

      <para>Host Controller Interface (HCI) provides a command interface to the
        baseband controller and link manager, and access to hardware status and
        control registers. This interface provides a uniform method of accessing
        the Bluetooth baseband capabilities. HCI layer on the Host exchanges
        data and commands with the HCI firmware on the Bluetooth hardware.
        The Host Controller Transport Layer (i.e. physical bus) driver provides
        both HCI layers with the ability to exchange information with each
        other.</para>

      <para>A single Netgraph node of type <emphasis>hci</emphasis> is
        created for a single Bluetooth device. The HCI node is normally
        connected to the Bluetooth device driver node (downstream) and
        the L2CAP node (upstream). All HCI operations must be performed
        on the HCI node and not on the device driver node. Default name
        for the HCI node is <quote>devicehci</quote>.
        For more details refer to the &man.ng.hci.4; manual page.</para>

      <para>One of the most common tasks is discovery of Bluetooth devices in
        RF proximity. This operation is called <emphasis>inquiry</emphasis>.
        Inquiry and other HCI related operations are done with the
        &man.hccontrol.8; utility. The example below shows how to find out
        which Bluetooth devices are in range. You should receive the list of
        devices in a few seconds. Note that a remote device will only answer
        the inquiry if it put into <emphasis>discoverable</emphasis>
        mode.</para>

      <screen>&prompt.user; <userinput>hccontrol -n ubt0hci inquiry</userinput>
Inquiry result, num_responses=1
Inquiry result #0
       BD_ADDR: 00:80:37:29:19:a4
       Page Scan Rep. Mode: 0x1
       Page Scan Period Mode: 00
       Page Scan Mode: 00
       Class: 52:02:04
       Clock offset: 0x78ef
Inquiry complete. Status: No error [00]</screen>

      <para><literal>BD_ADDR</literal> is unique address of a Bluetooth
        device, similar to MAC addresses of a network card. This address
        is needed for further communication with a device. It is possible
        to assign human readable name to a BD_ADDR.
        The <filename>/etc/bluetooth/hosts</filename> file contains information
        regarding the known Bluetooth hosts. The following example shows how
        to obtain human readable name that was assigned to the remote
        device:</para>

      <screen>&prompt.user; <userinput>hccontrol -n ubt0hci remote_name_request 00:80:37:29:19:a4</userinput>
BD_ADDR: 00:80:37:29:19:a4
Name: Pav's T39</screen>

      <para>If you perform an inquiry on a remote Bluetooth device, it will
        find your computer as <quote>your.host.name (ubt0)</quote>. The name
        assigned to the local device can be changed at any time.</para>

      <para>The Bluetooth system provides a point-to-point connection (only two
        Bluetooth units involved), or a point-to-multipoint connection. In the
        point-to-multipoint connection the connection is shared among several
        Bluetooth devices. The following example shows how to obtain the list
        of active baseband connections for the local device:</para>

      <screen>&prompt.user; <userinput>hccontrol -n ubt0hci read_connection_list</userinput>
Remote BD_ADDR    Handle Type Mode Role Encrypt Pending Queue State
00:80:37:29:19:a4     41  ACL    0 MAST    NONE       0     0 OPEN</screen>

      <para>A <emphasis>connection handle</emphasis> is useful when termination
        of the baseband connection is required. Note, that it is normally not
        required to do it by hand. The stack will automatically terminate
        inactive baseband connections.</para>

      <screen>&prompt.root; <userinput>hccontrol -n ubt0hci disconnect 41</userinput>
Connection handle: 41
Reason: Connection terminated by local host [0x16]</screen>

      <para>Refer to <command>hccontrol help</command> for a complete listing
        of available HCI commands. Most of the HCI commands do not require
        superuser privileges.</para>

    </sect2>

    <indexterm><primary>L2CAP</primary></indexterm>
    <sect2>
      <title>Logical Link Control and Adaptation Protocol (L2CAP)</title>

      <para>Logical Link Control and Adaptation Protocol (L2CAP) provides
        connection-oriented and connectionless data services to upper layer
        protocols with protocol multiplexing capability and segmentation and
        reassembly operation. L2CAP permits higher level protocols and
        applications to transmit and receive L2CAP data packets up to 64
        kilobytes in length.</para>

      <para>L2CAP is based around the concept of <emphasis>channels</emphasis>.
        Channel is a logical connection on top of baseband connection. Each
        channel is bound to a single protocol in a many-to-one fashion. Multiple
        channels can be bound to the same protocol, but a channel cannot be
        bound to multiple protocols. Each L2CAP packet received on a channel is
        directed to the appropriate higher level protocol. Multiple channels
        can share the same baseband connection.</para>

      <para>A single Netgraph node of type <emphasis>l2cap</emphasis> is
        created for a single Bluetooth device. The L2CAP node is normally
        connected to the Bluetooth HCI node (downstream) and Bluetooth sockets
        nodes (upstream). Default name for the L2CAP node is
        <quote>devicel2cap</quote>. For more details refer to the
        &man.ng.l2cap.4; manual page.</para>

      <para>A useful command is &man.l2ping.8;, which can be used to ping
        other devices. Some Bluetooth implementations might not return all of
        the data sent to them, so <literal>0 bytes</literal> in the following
        example is normal.</para>

      <screen>&prompt.root; <userinput>l2ping -a 00:80:37:29:19:a4</userinput>
0 bytes from 0:80:37:29:19:a4 seq_no=0 time=48.633 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=1 time=37.551 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=2 time=28.324 ms result=0
0 bytes from 0:80:37:29:19:a4 seq_no=3 time=46.150 ms result=0</screen>

      <para>The &man.l2control.8; utility is used to perform various operations
        on L2CAP nodes. This example shows how to obtain the list of logical
        connections (channels) and the list of baseband connections for the
        local device:</para>

      <screen>&prompt.user; <userinput>l2control -a 00:02:72:00:d4:1a read_channel_list</userinput>
L2CAP channels:
Remote BD_ADDR     SCID/ DCID   PSM  IMTU/ OMTU State
00:07:e0:00:0b:ca    66/   64     3   132/  672 OPEN
&prompt.user; <userinput>l2control -a 00:02:72:00:d4:1a read_connection_list</userinput>
L2CAP connections:
Remote BD_ADDR    Handle Flags Pending State
00:07:e0:00:0b:ca     41 O           0 OPEN</screen>

      <para>Another diagnostic tool is &man.btsockstat.1;. It does a job
        similar to as &man.netstat.1; does, but for Bluetooth network-related
        data structures. The example below shows the same logical connection as
        &man.l2control.8; above.</para>

      <screen>&prompt.user; <userinput>btsockstat</userinput>
Active L2CAP sockets
PCB      Recv-Q Send-Q Local address/PSM       Foreign address   CID   State
c2afe900      0      0 00:02:72:00:d4:1a/3     00:07:e0:00:0b:ca 66    OPEN
Active RFCOMM sessions
L2PCB    PCB      Flag MTU   Out-Q DLCs State
c2afe900 c2b53380 1    127   0     Yes  OPEN
Active RFCOMM sockets
PCB      Recv-Q Send-Q Local address     Foreign address   Chan DLCI State
c2e8bc80      0    250 00:02:72:00:d4:1a 00:07:e0:00:0b:ca 3    6    OPEN</screen>

    </sect2>

    <indexterm><primary>RFCOMM</primary></indexterm>
    <sect2>
      <title>RFCOMM Protocol</title>

      <para>The RFCOMM protocol provides emulation of serial ports over the
        L2CAP protocol. The protocol is based on the ETSI standard TS 07.10.
        RFCOMM is a simple transport protocol, with additional provisions for
        emulating the 9 circuits of RS-232 (EIATIA-232-E) serial ports. The
        RFCOMM protocol supports up to 60 simultaneous connections (RFCOMM
        channels) between two Bluetooth devices.</para>

      <para>For the purposes of RFCOMM, a complete communication path involves
        two applications running on different devices (the communication
        endpoints) with a communication segment between them. RFCOMM is intended
        to cover applications that make use of the serial ports of the devices
        in which they reside. The communication segment is a Bluetooth link from
        one device to another (direct connect).</para>

      <para>RFCOMM is only concerned with the connection between the devices in
        the direct connect case, or between the device and a modem in the
        network case. RFCOMM can support other configurations, such as modules
        that communicate via Bluetooth wireless technology on one side and
        provide a wired interface on the other side.</para>

      <para>In &os; the RFCOMM protocol is implemented at the Bluetooth sockets
        layer.</para>
    </sect2>

    <indexterm><primary>pairing</primary></indexterm>
    <sect2>
      <title>Pairing of Devices</title>

      <para>By default, Bluetooth communication is not authenticated, and any
        device can talk to any other device. A Bluetooth device (for example,
        cellular phone) may choose to require authentication to provide a
        particular service (for example, Dial-Up service). Bluetooth
        authentication is normally done with <emphasis>PIN codes</emphasis>.
        A PIN code is an ASCII string up to 16 characters in length. User is
        required to enter the same PIN code on both devices. Once user has
        entered the PIN code, both devices will generate a
        <emphasis>link key</emphasis>. After that the link key can be stored
        either in the devices themselves or in a persistent storage. Next time
        both devices will use previously generated link key. The described
        above procedure is called <emphasis>pairing</emphasis>. Note that if
        the link key is lost by any device then pairing must be repeated.</para>

      <para>The &man.hcsecd.8; daemon is responsible for handling of all
        Bluetooth authentication requests. The default configuration file is
        <filename>/etc/bluetooth/hcsecd.conf</filename>. An example section for
        a cellular phone with the PIN code arbitrarily set to
        <quote>1234</quote> is shown below:</para>

      <programlisting>device {
        bdaddr  00:80:37:29:19:a4;
        name    "Pav's T39";
        key     nokey;
        pin     "1234";
      }</programlisting>

      <para>There is no limitation on PIN codes (except length). Some devices
        (for example Bluetooth headsets) may have a fixed PIN code built in.
        The <option>-d</option> switch forces the &man.hcsecd.8; daemon to stay
        in the foreground, so it is easy to see what is happening. Set the
        remote device to receive pairing and initiate the Bluetooth connection
        to the remote device. The remote device should say that pairing was
        accepted, and request the PIN code. Enter the same PIN code as you
        have in <filename>hcsecd.conf</filename>. Now your PC and the remote
        device are paired. Alternatively, you can initiate pairing on the remote
        device.  The following is a sample of the
        <application>hcsecd</application> daemon output:</para>

<programlisting>hcsecd[16484]: Got Link_Key_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', link key doesn't exist
hcsecd[16484]: Sending Link_Key_Negative_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Got PIN_Code_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4
hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', PIN code exists
hcsecd[16484]: Sending PIN_Code_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4</programlisting>

    </sect2>

    <indexterm><primary>SDP</primary></indexterm>
    <sect2>
      <title>Service Discovery Protocol (SDP)</title>
      <para>The Service Discovery Protocol (SDP) provides the means for client
        applications to discover the existence of services provided by server
        applications as well as the attributes of those services. The attributes
        of a service include the type or class of service offered and the
        mechanism or protocol information needed to utilize the service.</para>

      <para>SDP involves communication between a SDP server and a SDP client.
        The server maintains a list of service records that describe the
        characteristics of services associated with the server. Each service
        record contains information about a single service. A client may 
        retrieve information from a service record maintained by the SDP server
        by issuing a SDP request. If the client, or an application associated
        with the client, decides to use a service, it must open a separate
        connection to the service provider in order to utilize the service.
        SDP provides a mechanism for discovering services and their attributes,
        but it does not provide a mechanism for utilizing those services.</para>

      <para>Normally, a SDP client searches for services based on some desired
        characteristics of the services. However, there are times when it is
        desirable to discover which types of services are described by an SDP
        server's service records without any a priori information about the
        services. This process of looking for any offered services is called
        <emphasis>browsing</emphasis>.</para>
 
      <para>The Bluetooth SDP server &man.sdpd.8; and command line client
        &man.sdpcontrol.8; are included in the standard &os; installation.
        The following example shows how to perform a SDP browse query.</para>

      <screen>&prompt.user; <userinput>sdpcontrol -a 00:01:03:fc:6e:ec browse</userinput>
Record Handle: 00000000
Service Class ID List:
        Service Discovery Server (0x1000)
Protocol Descriptor List:
        L2CAP (0x0100)
                Protocol specific parameter #1: u/int/uuid16 1
                Protocol specific parameter #2: u/int/uuid16 1

Record Handle: 0x00000001
Service Class ID List:
        Browse Group Descriptor (0x1001)

Record Handle: 0x00000002
Service Class ID List:
        LAN Access Using PPP (0x1102)
Protocol Descriptor List:
        L2CAP (0x0100)
        RFCOMM (0x0003)
                Protocol specific parameter #1: u/int8/bool 1
Bluetooth Profile Descriptor List:
        LAN Access Using PPP (0x1102) ver. 1.0
</screen>

      <para>... and so on. Note that each service has a list of attributes
        (RFCOMM channel for example). Depending on the service you might need to
        make a note of some of the attributes. Some Bluetooth implementations do
        not support service browsing and may return an empty list. In this case
        it is possible to search for the specific service. The example below
        shows how to search for the OBEX Object Push (OPUSH) service:</para>

      <screen>&prompt.user; <userinput>sdpcontrol -a 00:01:03:fc:6e:ec search OPUSH</userinput></screen>

      <para>Offering services on &os; to Bluetooth clients is done with the
        &man.sdpd.8; server:</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>

    <indexterm><primary>OBEX</primary></indexterm>
    <sect2>
      <title>OBEX Object Push (OPUSH) Profile</title>
      <para>OBEX is a widely used protocol for simple file transfers between
        mobile devices. Its main use is in infrared communication, where it is
        used for generic file transfers between notebooks or PDAs,
        and for sending business cards or calendar entries between cellular
        phones and other devices with PIM applications.</para>

      <para>The OBEX server and client are implemented as a third-party package
        <application>obexapp</application>, which is available as
	<filename role="package">comms/obexapp</filename> port.</para>

      <para>OBEX client is used to push and/or pull objects from the OBEX server.
        An object can, for example, be a business card or an appointment.
        The OBEX client can obtain RFCOMM channel number from the remote device
        via SDP. This can be done by specifying service name instead of RFCOMM
        channel number. Supported service names are: IrMC, FTRN and OPUSH.
        It is possible to specify RFCOMM channel as a number. Below is an
        example of an OBEX session, where device information object is pulled
        from the cellular phone, and a new object (business card) is pushed
        into the phone's directory.</para>

      <screen>&prompt.user; <userinput>obexapp -a 00:80:37:29:19:a4 -C IrMC</userinput>
obex&gt; get telecom/devinfo.txt devinfo-t39.txt
Success, response: OK, Success (0x20)
obex&gt; put new.vcf
Success, response: OK, Success (0x20)
obex&gt; di
Success, response: OK, Success (0x20)</screen>

      <para>In order to provide OBEX Object Push service,
        &man.sdpd.8; server must be running. A root folder, where all incoming
        objects will be stored, must be created. The default path to the root
        folder is <filename>/var/spool/obex</filename>. Finally, start OBEX
        server on valid RFCOMM channel number. The OBEX server will
        automatically register OBEX Object Push service with the local SDP
        daemon. The example below shows how to start OBEX server.</para>

      <screen>&prompt.root; <userinput>obexapp -s -C 10</userinput></screen>
    </sect2>

    <sect2>
      <title>Serial Port Profile (SPP)</title>
      <para>The Serial Port Profile (SPP) allows Bluetooth devices to perform
        RS232 (or similar) serial cable emulation. The scenario covered by this
        profile deals with legacy applications using Bluetooth as a cable
        replacement, through a virtual serial port abstraction.</para>

      <para>The &man.rfcomm.sppd.1; utility implements the Serial Port profile.
        A pseudo tty is used as a virtual serial port abstraction. The example
        below shows how to connect to a remote device Serial Port service.
        Note that you do not have to specify a RFCOMM channel -
        &man.rfcomm.sppd.1; can obtain it from the remote device via SDP.
        If you would like to override this, specify a RFCOMM channel on the
        command line.</para>

      <screen>&prompt.root; <userinput>rfcomm_sppd -a 00:07:E0:00:0B:CA -t /dev/ttyp6</userinput>
rfcomm_sppd[94692]: Starting on /dev/ttyp6...</screen>

      <para>Once connected, the pseudo tty can be used as serial port:</para>

      <screen>&prompt.root; <userinput>cu -l ttyp6</userinput></screen>

    </sect2>

    <sect2>
      <title>Troubleshooting</title>

      <sect3>
        <title>A remote device cannot connect</title>
        <para>Some older Bluetooth devices do not support role switching.
          By default, when &os; is accepting a new connection, it tries to
          perform a role switch and become master. Devices, which do not
          support this will not be able to connect. Note that role switching is
          performed when a new connection is being established, so it is not
          possible to ask the remote device if it does support role switching.
          There is a HCI option to disable role switching on the local
          side:</para>

        <screen>&prompt.root; <userinput>hccontrol -n ubt0hci write_node_role_switch 0</userinput></screen>

      </sect3>

      <sect3>
        <title>Something is going wrong, can I see what exactly is happening?</title>
        <para>Yes, you can.  Use the third-party package
          <application>hcidump</application>, which is available as
	  <filename role="package">comms/hcidump</filename> port.
          The <application>hcidump</application> utility is similar to
          &man.tcpdump.1;. It can be used to display the content of the Bluetooth
          packets on the terminal and to dump the Bluetooth packets to a
          file.</para>
      </sect3>

    </sect2>

  </sect1>

  <sect1 id="network-bridging">
    <sect1info>
      <authorgroup>
        <author>
          <firstname>Steve</firstname>
      	  <surname>Peterson</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 two common situations in which a bridge is used
	today.</para>

      <sect3>
	<title>High Traffic on a Segment</title>

	<para>Situation one is where your physical network segment is
	  overloaded with traffic, but you do not want for whatever reason to
	  subnet the network and interconnect the subnets with a
	  router.</para>

	<para>Let us consider an example of a newspaper where the Editorial and
	  Production departments are on the same subnetwork.  The Editorial
	  users all use server <hostid>A</hostid> for file service, and the Production users
	  are on server <hostid>B</hostid>.  An Ethernet network is used to connect all users together,
	  and high loads on the network are slowing things down.</para>

	<para>If the Editorial users could be segregated on one
	  network segment and the Production users on another, the two
	  network segments could be connected with a bridge.  Only the
	  network traffic destined for interfaces on the
	  <quote>other</quote> side of the bridge would be sent to the
	  other network, reducing congestion on each network
	  segment.</para>
      </sect3>

      <sect3>
	<title>Filtering/Traffic Shaping Firewall</title>
	<indexterm><primary>firewall</primary></indexterm>
	<indexterm><primary>NAT</primary></indexterm>

	<para>The second common situation is where firewall functionality is
	  needed without 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>
    </sect2>

    <sect2>
      <title>Configuring a Bridge</title>

      <sect3>
	<title>Network Interface Card Selection</title>

	<para>A bridge requires at least two network cards to function.
	  Unfortunately, not all network interface cards as of FreeBSD&nbsp;4.0
	  support bridging.  Read &man.bridge.4; for details on the cards that
	  are supported.</para>

	<para>Install and test the two network cards before continuing.</para>
      </sect3>

      <sect3>
	<title>Kernel Configuration Changes</title>
	<indexterm>
	  <primary>kernel options</primary>
	  <secondary>BRIDGE</secondary>
	</indexterm>

	<para>To enable kernel support for bridging, add the:</para>

	<programlisting>options BRIDGE</programlisting>

	<para>statement to your kernel configuration file, and rebuild your
	  kernel.</para>
      </sect3>

      <sect3>
	<title>Firewall Support</title>
	<indexterm><primary>firewall</primary></indexterm>
	<para>If you are planning to use the bridge as a firewall, you
	  will need to add the <literal>IPFIREWALL</literal> option as
	  well.  Read <xref linkend="firewalls"> for general
	  information on configuring the bridge as a firewall.</para>

	<para>If you need to allow non-IP packets (such as ARP) to flow
	  through the bridge, there is a firewall option that
	  must be set.  This option is
	  <literal>IPFIREWALL_DEFAULT_TO_ACCEPT</literal>.  Note that this
	  changes the default rule for the firewall to accept any packet.
	  Make sure you know how this changes the meaning of your ruleset
	  before you set it.</para>
      </sect3>

      <sect3>
	<title>Traffic Shaping Support</title>

	<para>If you want to use the bridge as a traffic shaper, you will need
	  to add the <literal>DUMMYNET</literal> option to your kernel
	  configuration.  Read &man.dummynet.4; for further
	  information.</para>
      </sect3>
    </sect2>

    <sect2>
      <title>Enabling the Bridge</title>

      <para>Add the line:</para>

      <programlisting>net.link.ether.bridge.enable=1</programlisting>

      <para>to <filename>/etc/sysctl.conf</filename> to enable the bridge at
	runtime, and the line:</para>

      <programlisting>net.link.ether.bridge.config=<replaceable>if1</replaceable>,<replaceable>if2</replaceable></programlisting>

      <para>to enable bridging on the specified interfaces (replace
	<replaceable>if1</replaceable> and
	<replaceable>if2</replaceable> with the names of your two
	network interfaces).  If you want the bridged packets to be
	filtered by &man.ipfw.8;, you should add:</para>

      <programlisting>net.link.ether.bridge.ipfw=1</programlisting>

      <para>as well.</para>

      <para>For versions prior to &os;&nbsp;5.2-RELEASE, use instead the following
	lines:</para>

      <programlisting>net.link.ether.bridge=1
net.link.ether.bridge_cfg=<replaceable>if1</replaceable>,<replaceable>if2</replaceable>
net.link.ether.bridge_ipfw=1</programlisting>

    </sect2>
    
    <sect2>
      <title>Other Information</title>

      <para>If you want to be able to &man.ssh.1; into the bridge from the network,
	it is correct to assign one of the network cards an IP address.  The
	consensus is that assigning both cards an address is a bad
	idea.</para>

      <para>If you have multiple bridges on your network, there cannot be more
	than one path between any two workstations.  Technically, this means
	that there is no support for spanning tree link management.</para>

      <para>A bridge can add latency to your &man.ping.8; times, especially for
        traffic from one segment to another.</para>
      
    </sect2>
  </sect1>

  <sect1 id="network-diskless">
    <sect1info>
      <authorgroup>
        <author>
          <firstname>Jean-Fran&ccedil;ois</firstname>
          <surname>Dock&egrave;s</surname>
          <contrib>Updated by </contrib>
        </author>
      </authorgroup>
      <authorgroup>
	<author>
	  <firstname>Alex</firstname>
	  <surname>Dupre</surname>
	  <contrib>Reorganized and enhanced by </contrib>
	</author>
      </authorgroup>
    </sect1info>
    <title>Diskless Operation</title>

    <indexterm><primary>diskless workstation</primary></indexterm>
    <indexterm><primary>diskless operation</primary></indexterm>

    <para>A FreeBSD machine can boot over the network and operate without a
      local disk, using filesystems 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 filesystem
	  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> filesystem, and a shared
	  read-only <filename>/usr</filename>.</para>
	<para>The root filesystem 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.mfs.8; (&os;&nbsp;4.X) or &man.md.4; (&os;&nbsp;5.X) filesystems.  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; releases 4.9-RELEASE and 5.2.1-RELEASE.  The text is
      primarily structured for 4.X usage.  Notes have been inserted where
      appropriate to indicate 5.X changes.</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 with 4.X systems.  Because 5.X kernels
	    normally let the &man.loader.8; do more work for them,
	    <acronym>PXE</acronym> is preferred for 5.X systems.</para>

	  <para>If your <acronym>BIOS</acronym> and network cards support
	    <acronym>PXE</acronym>, you should probably use it.  However,
	    it is still possible to start a 5.X system with
	    <application>Etherboot</application>.</para>
	</listitem>

	<listitem>
	  <para>Finally, the machine needs to access its filesystems.
	    <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>As of release 4.9, <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 role="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 filesystem, 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>/etc/defaults/make.conf</filename> (or
	  <filename>/usr/share/examples/etc/make.conf</filename> for 5.X
	  systems) for instructions.</para>

	<para>There are two other undocumented <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> (the latter only exists
	  on &os;&nbsp;5.X).</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:</para>
	    <screen>&prompt.root; <userinput>kill -HUP `cat /var/run/inetd.pid`</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 filesystem 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 filesystem 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>kill -HUP `cat /var/run/mountd.pid`</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 filesystem 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>LINT</filename> in 4.X or
	  <filename>NOTES</filename> on 5.X).</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 5.X 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 filesystem for the diskless
	  workstations, in the location listed as
	  <literal>root-path</literal> in
	  <filename>dhcpd.conf</filename>.  The following sections describe
	  two ways to do it.</para>

	<sect4>
	  <title>Using the <filename>clone_root</filename> Script</title>

	<para>This is the quickest way to create a root filesystem, but
	  currently it is only supported on &os;&nbsp;4.X.  This shell script
	  is located at
	  <filename>/usr/share/examples/diskless/clone_root</filename>
	  and needs customization, at least to adjust
	  the place where the filesystem will be created (the
	  <literal>DEST</literal> variable).</para>

	<para>Refer to the comments at the top of the script for
	    instructions.  They explain how the base filesystem is built,
	    and how files may be selectively overridden by versions specific
	    to diskless operation, to a subnetwork, or to an individual
	    workstation.  They also give examples for the diskless
	    <filename>/etc/fstab</filename> and <filename>
	    /etc/rc.conf</filename> files.</para>

	  <para>The <filename>README</filename> files in
	    <filename>/usr/share/examples/diskless</filename> contain a lot
	    of interesting background information, but, together with the
	    other examples in the <filename>diskless</filename> directory,
	    they actually document a configuration method which is distinct
	    from the one used by <filename>clone_root</filename> and
	    the system startup scripts in
	    <filename role="directory">/etc</filename>, which is a little
	    confusing.  Use them for reference only, except if you prefer 
	    the method that they describe, in which case you will need
	    customized <filename>rc</filename> scripts.</para>
	</sect4>

	<sect4>
	  <title>Using the Standard <command>make world</command>
	    Procedure</title>

	  <para>This method can be applied to either &os;&nbsp;4.X or 5.X and
	    will install a complete virgin system (not only the root filesystem)
	    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 world && make kernel
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>.  One of the methods commonly
	  used to do this has been discontinued in release 5.X.</para>

	<sect4>
	  <title><acronym>NFS</acronym> Swap with &os;&nbsp;4.X</title>

	  <para>The swap file location and size can be specified with
	    BOOTP/<acronym>DHCP</acronym> &os;-specific options 128 and 129.
	    Examples of configuration files for
	    <application>ISC DHCP 3.0</application> or
	    <application>bootpd</application> follow:</para>

	<procedure>
	  <step><para>Add the following lines to
	  <filename>dhcpd.conf</filename>:</para>
	    <programlisting>
# Global section
option swap-path code 128 = string;
option swap-size code 129 = integer 32;

host margaux {
  ... # Standard lines, see above
  option swap-path <replaceable>"192.168.4.4:/netswapvolume/netswap"</replaceable>;
  option swap-size <replaceable>64000</replaceable>;
}
	    </programlisting>

	    <para><literal>swap-path</literal> is the path to a directory
	      where swap files will be located.  Each file will be named
	      <filename>swap.<replaceable>client-ip</replaceable></filename>.</para>

	    <para>Older versions of <application>dhcpd</application> used a syntax of
	      <literal>option option-128 "...</literal>, which is no
	      longer supported.</para>
	    <para><filename>/etc/bootptab</filename> would use the
	      following syntax instead:</para>

	    <programlisting>T128="192.168.4.4:/netswapvolume/netswap":T129=0000fa00</programlisting>

	    <note><para>In <filename>/etc/bootptab</filename>, the swap
	      size must be expressed in hexadecimal format.</para></note>
	  </step>

	  <step>
	    <para>On the <acronym>NFS</acronym> swap file server, create the swap
	    file(s):</para>
            <screen>
&prompt.root; <userinput>mkdir <replaceable>/netswapvolume/netswap</replaceable></userinput>
&prompt.root; <userinput>cd <replaceable>/netswapvolume/netswap</replaceable></userinput>
&prompt.root; <userinput>dd if=/dev/zero bs=1024 count=<replaceable>64000</replaceable> of=swap.<replaceable>192.168.4.6</replaceable></userinput>
&prompt.root; <userinput>chmod 0600 swap.<replaceable>192.168.4.6</replaceable></userinput>
            </screen>
	    <para><replaceable>192.168.4.6</replaceable> is the IP address
	      for the diskless client.</para>
	  </step>

	  <step>
	    <para>On the <acronym>NFS</acronym> swap file server, add the following line to
	    <filename>/etc/exports</filename>:</para>
	    <programlisting>
<replaceable>/netswapvolume</replaceable>  -maproot=0:10 -alldirs <replaceable>margaux corbieres</replaceable>
	    </programlisting>
	    <para>Then tell <application>mountd</application> to reread the
		<filename>exports</filename> file, as above.</para>
	  </step>
	</procedure>
	</sect4>

	<sect4>
	  <title><acronym>NFS</acronym> Swap with &os&nbsp;5.X</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 writeable 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 filesystem is not running FreeBSD,
	    you will have to create the root filesystem 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 run
	    <command>MAKEDEV</command> on the FreeBSD machine
	    to create the correct device entries (FreeBSD 5.0 and later
	    use &man.devfs.5; to allocate device nodes transparently for
	    the user, running <command>MAKEDEV</command> on these
	    versions is pointless).</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.  Starting with
	FreeBSD&nbsp;4.4, 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&nbsp;Kbs, even though you have a 128&nbsp;Kbs connection.
	To fully utilize the 128&nbsp;Kbs that ISDN is capable of,
	you must move the TA to a synchronous serial card.</para>

      <para>Do not be fooled into buying an internal TA and thinking you have
	avoided the synchronous/asynchronous issue.  Internal TA's simply have
	a standard PC serial port chip built into them.  All this will do is
	save you having to buy another serial cable and find another empty
	electrical socket.</para>

      <para>A synchronous card with a TA is at least as fast as a stand-alone
	router, and with a simple 386 FreeBSD box driving it, probably more
	flexible.</para>

      <para>The choice of synchronous card/TA v.s. stand-alone router is largely a
	religious issue.  There has been some discussion of this in
	the mailing lists.  We suggest you search the <ulink
	url="&url.base;/search/index.html">archives</ulink> for
	the complete discussion.</para>
    </sect2>

    <sect2>
      <title>Stand-alone ISDN Bridges/Routers</title>
      <indexterm>
        <primary>ISDN</primary>
	<secondary>stand-alone bridges/routers</secondary>
      </indexterm>
      <para>ISDN bridges or routers are not at all specific to FreeBSD
	or any other operating system.  For a more complete
	description of routing and bridging technology, please refer
	to a networking reference book.</para>

      <para>In the context of this section, the terms router and bridge will
	be used interchangeably.</para>

      <para>As the cost of low end ISDN routers/bridges comes down, it
	will likely become a more and more popular choice.  An ISDN
	router is a small box that plugs directly into your local
	Ethernet network, and manages its own connection to the other
	bridge/router.  It has built in software to communicate via
	PPP and other popular protocols.</para>

      <para>A router will allow you much faster throughput than a
	standard TA, since it will be using a full synchronous ISDN
	connection.</para>

      <para>The main problem with ISDN routers and bridges is that
	interoperability between manufacturers can still be a problem.
	If you are planning to connect to an Internet provider, you
	should discuss your needs with them.</para>

      <para>If you are planning to connect two LAN segments together,
	such as your home LAN to the office LAN, this is the simplest
	lowest
	maintenance solution.  Since you are buying the equipment for
	both sides of the connection you can be assured that the link
	will work.</para>

      <para>For example to connect a home computer or branch office
	network to a head office network the following setup could be
	used:</para>

      <example>
	<title>Branch Office or Home Network</title>

	<indexterm><primary>10 base 2</primary></indexterm>
	<para>Network uses a bus based topology with 10 base 2
	  Ethernet (<quote>thinnet</quote>).  Connect router to network cable with
	  AUI/10BT transceiver, if necessary.</para>

        <mediaobject>
          <imageobject>
            <imagedata fileref="advanced-networking/isdn-bus">
          </imageobject>

	  <textobject>
	    <literallayout class="monospaced">---Sun workstation
|
---FreeBSD box
|
---Windows 95
|
Stand-alone router
   |
ISDN BRI line</literallayout>
          </textobject>

	  <textobject>
	    <phrase>10 Base 2 Ethernet</phrase>
	  </textobject>
	</mediaobject>

	<para>If your home/branch office is only one computer you can use a
	  twisted pair crossover cable to connect to the stand-alone router
	  directly.</para>
      </example>

      <example>
	<title>Head Office or Other LAN</title>

	<indexterm><primary>10 base T</primary></indexterm>
	<para>Network uses a star topology with 10 base T Ethernet
  	  (<quote>Twisted Pair</quote>).</para>

        <mediaobject>
          <imageobject>
            <imagedata fileref="advanced-networking/isdn-twisted-pair">
          </imageobject>

	  <textobject>
	    <literallayout class="monospaced">    -------Novell Server
    | H |
    |   ---Sun
    |   |
    | U ---FreeBSD
    |   |
    |   ---Windows 95
    | B |
    |___---Stand-alone router
                |
        ISDN BRI line</literallayout>
	  </textobject>

	  <textobject>
	    <phrase>ISDN Network Diagram</phrase>
	  </textobject>
	</mediaobject>
      </example>

      <para>One large advantage of most routers/bridges is that they allow you
	to have 2 <emphasis>separate independent</emphasis> PPP connections to
	2 separate sites at the <emphasis>same</emphasis> time.  This is not
	supported on most TA's, except for specific (usually expensive) models
	that
	have two serial ports.  Do not confuse this with channel bonding, MPP,
	etc.</para>

      <para>This can be a very useful feature if, for example, you
	have an dedicated ISDN connection at your office and would
	like to tap into it, but do not want to get another ISDN line
	at work.  A router at the office location can manage a
	dedicated B channel connection (64&nbsp;Kbps) to the Internet
	and use the other B channel for a separate data connection.
	The second B channel can be used for dial-in, dial-out or
	dynamically bonding (MPP, etc.) with the first B channel for
	more bandwidth.</para>

      <indexterm><primary>IPX/SPX</primary></indexterm>
      <para>An Ethernet bridge will also allow you to transmit more than just
	IP traffic.  You can also send IPX/SPX or whatever other protocols you
	use.</para>
    </sect2>
  </sect1>

  <sect1 id="network-natd">
    <sect1info>
      <authorgroup>
        <author>
          <firstname>Chern</firstname>
          <surname>Lee</surname>
          <contrib>Contributed by </contrib>
        </author>
      </authorgroup>
    </sect1info>
    <title>Network Address Translation</title>

    <sect2 id="network-natoverview">
      <title>Overview</title>
      <indexterm>
        <primary><application>natd</application></primary>
      </indexterm>
      <para>FreeBSD's Network Address Translation daemon, commonly known as
        &man.natd.8; is a daemon that accepts incoming raw IP packets,
        changes the source to the local machine and re-injects these packets
        back into the outgoing IP packet stream.  &man.natd.8; does this by changing
        the source IP address and port such that when data is received back,
        it is able to determine the original location of the data and forward
        it back to its original requester.</para>
      <indexterm><primary>Internet connection sharing</primary></indexterm>
      <indexterm><primary>NAT</primary></indexterm>
      <para>The most common use of NAT is to perform what is commonly known as
        Internet Connection Sharing.</para>
    </sect2>

    <sect2 id="network-natsetup">
      <title>Setup</title>
      <para>Due to the diminishing IP space in IPv4, and the increased number
        of users on high-speed consumer lines such as cable or DSL, people are
        increasingly in need of an Internet Connection Sharing solution.  The
        ability to connect several computers online through one connection and
        IP address makes &man.natd.8; a reasonable choice.</para>

      <para>Most commonly, a user has a machine connected to a cable or DSL
        line with one IP address and wishes to use this one connected computer to
        provide Internet access to several more over a LAN.</para>

      <para>To do this, the FreeBSD machine on the Internet must act as a
        gateway.  This gateway machine must have two NICs&mdash;one for connecting
        to the Internet router, the other connecting to a LAN.  All the
        machines on the LAN are connected through a hub or switch.</para>

      <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">
      <indexterm>
        <primary>kernel</primary>
	<secondary>configuration</secondary>
      </indexterm>
      <title>Configuration</title>
      <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: &lt;Printer&gt; on ppbus0
lpt0: Interrupt-driven port</screen>

      <para>The parallel port must be an interrupt driven port, under
	&os;&nbsp;4.X, you should have a line similar to the
	following in your kernel configuration file:</para>

      <programlisting>device ppc0 at isa? irq 7</programlisting>

      <para>Under &os;&nbsp;5.X, the
	<filename>/boot/device.hints</filename> file should contain the
	following lines:</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
	directly use the &man.ifconfig.8; command.  Under
	&os;&nbsp;4.X like this:</para>

      <screen>&prompt.root; <userinput>ifconfig lp0</userinput>
lp0: flags=8810&lt;POINTOPOINT,SIMPLEX,MULTICAST&gt; mtu 1500</screen>

      <para>and for &os;&nbsp;5.X:</para>

      <screen>&prompt.root; <userinput>ifconfig plip0</userinput>
plip0: flags=8810&lt;POINTOPOINT,SIMPLEX,MULTICAST&gt; mtu 1500</screen>

      <note><para>The device name used for parallel interface is
	different between &os;&nbsp;4.X
	(<devicename>lp<replaceable>X</replaceable></devicename>)
	and &os;&nbsp;5.X
	(<devicename>plip<replaceable>X</replaceable></devicename>).</para></note>

      <para>Plug in 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 connect
	the host <hostid>host1</hostid> running &os;&nbsp;4.X with <hostid>host2</hostid> running &os;&nbsp;5.X:</para>

      <programlisting>                 host1 &lt;-----&gt; host2
IP Address    10.0.0.1      10.0.0.2</programlisting>

      <para>Configure the interface on <hostid>host1</hostid> by doing:</para>

      <screen>&prompt.root; <userinput>ifconfig lp0 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 lp0</userinput>
lp0: flags=8851&lt;UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST&gt; mtu 1500
        inet 10.0.0.1 --&gt; 10.0.0.2 netmask 0xff000000
&prompt.root; <userinput>netstat -r</userinput>
Routing tables

Internet:
Destination        Gateway          Flags     Refs     Use      Netif Expire
host2              host1              UH          0       0       lp0
&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 know as IPng <quote>IP next generation</quote>) is
      the new version of the well known IP protocol (also know 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 private address spaces
	  (<hostid role="ipaddr">10.0.0.0/8</hostid>,
	  <hostid role="ipaddr">192.168.0.0/24</hostid>,
	  etc.) 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>

      <listitem>
	<para><ulink url="http://www.6bone.net">6bone.net</ulink></para>
      </listitem>
    </itemizedlist>

    <sect2>
      <title>Background on IPv6 Addresses</title>
      <para>There are different types of IPv6 addresses: Unicast, Anycast and
	Multicast.</para>

      <para>Unicast addresses are the well known addresses.  A packet sent
	to a unicast address arrives exactly at the interface belonging to
	the address.</para>

      <para>Anycast addresses are syntactically indistinguishable from unicast
	addresses but they address a group of interfaces.  The packet destined for
	an anycast address will arrive at the nearest (in router metric)
	interface.  Anycast addresses may only be used by routers.</para>

      <para>Multicast addresses identify a group of interfaces.  A packet destined
	for a multicast address will arrive at all interfaces belonging to the
	multicast group.</para>

	<note><para>The IPv4 broadcast address (usually <hostid role="ipaddr">xxx.xxx.xxx.255</hostid>) is expressed
	  by multicast addresses in IPv6.</para></note>

      <table frame="none">
	<title>Reserved IPv6 addresses</title>

	<tgroup cols="4">
	  <thead>
	    <row>
	      <entry>IPv6 address</entry>
	      <entry>Prefixlength (Bits)</entry>
	      <entry>Description</entry>
	      <entry>Notes</entry>
	    </row>
	  </thead>

	  <tbody>
	    <row>
	      <entry><hostid role="ip6addr">::</hostid></entry>
	      <entry>128 bits</entry>
	      <entry>unspecified</entry>
	      <entry>cf. <hostid role="ipaddr">0.0.0.0</hostid> in
		IPv4</entry>
	    </row>

	    <row>
	      <entry><hostid role="ip6addr">::1</hostid></entry>
	      <entry>128 bits</entry>
	      <entry>loopback address</entry>
	      <entry>cf. <hostid role="ipaddr">127.0.0.1</hostid> in
		IPv4</entry>
	    </row>

	    <row>
	      <entry><hostid
		role="ip6addr">::00:xx:xx:xx:xx</hostid></entry>
	      <entry>96 bits</entry>
	      <entry>embedded IPv4</entry>
	      <entry>The lower 32 bits are the IPv4 address.  Also
		called <quote>IPv4 compatible IPv6
		address</quote></entry>
	    </row>

	    <row>
	      <entry><hostid
		role="ip6addr">::ff:xx:xx:xx:xx</hostid></entry>
	      <entry>96 bits</entry>
	      <entry>IPv4 mapped IPv6 address</entry>
	      <entry>The lower 32 bits are the IPv4 address.
		For hosts which do not support IPv6.</entry>
	    </row>

	    <row>
	      <entry><hostid role="ip6addr">fe80::</hostid> - <hostid
		role="ip6addr">feb::</hostid></entry>
	      <entry>10 bits</entry>
	      <entry>link-local</entry>
	      <entry>cf. loopback address in IPv4</entry>
	    </row>

	    <row>
	      <entry><hostid role="ip6addr">fec0::</hostid> - <hostid
		role="ip6addr">fef::</hostid></entry>
	      <entry>10 bits</entry>
	      <entry>site-local</entry>
	      <entry>&nbsp;</entry>
	    </row>

	    <row>
	      <entry><hostid role="ip6addr">ff::</hostid></entry>
	      <entry>8 bits</entry>
	      <entry>multicast</entry>
	      <entry>&nbsp;</entry>
	    </row>

	    <row>
	      <entry><hostid role="ip6addr">001</hostid> (base
		2)</entry>
	      <entry>3 bits</entry>
	      <entry>global unicast</entry>
	      <entry>All global unicast addresses are assigned from
		this pool.  The first 3 bits are
		<quote>001</quote>.</entry>
	    </row>
	  </tbody>
	</tgroup>
      </table>
    </sect2>

    <sect2>
      <title>Reading IPv6 Addresses</title>
      <para>The canonical form is represented as: <hostid role="ip6addr">x:x:x:x:x:x:x:x</hostid>, each
	<quote>x</quote> being a 16 Bit hex value.  For example
	<hostid role="ip6addr">FEBC:A574:382B:23C1:AA49:4592:4EFE:9982</hostid></para>

      <para>Often an address will have long substrings of all zeros
	therefore one such substring per address can be abbreviated by <quote>::</quote>.
	Also up to three leading <quote>0</quote>s per hexquad can be omitted.
	For example <hostid role="ip6addr">fe80::1</hostid>
	corresponds to the canonical form
	<hostid role="ip6addr">fe80:0000:0000:0000:0000:0000:0000:0001</hostid>.</para>

      <para>A third form is to write the last 32 Bit part in the
	well known (decimal) IPv4 style with dots <quote>.</quote>
	as separators.  For example
	<hostid role="ip6addr">2002::10.0.0.1</hostid>
	corresponds to the (hexadecimal) canonical representation
	<hostid role="ip6addr">2002:0000:0000:0000:0000:0000:0a00:0001</hostid>
	which in turn is equivalent to
	writing <hostid role="ip6addr">2002::a00:1</hostid>.</para>

      <para>By now the reader should be able to understand the following:</para>

      <screen>&prompt.root; <userinput>ifconfig</userinput></screen>

      <programlisting>rl0: flags=8943&lt;UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST&gt; mtu 1500
         inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255
         inet6 fe80::200:21ff:fe03:8e1%rl0 prefixlen 64 scopeid 0x1
         ether 00:00:21:03:08:e1
         media: Ethernet autoselect (100baseTX )
         status: active</programlisting>

      <para><hostid role="ip6addr">fe80::200:21ff:fe03:8e1%rl0</hostid>
	is an auto configured link-local address.  It is generated from the MAC
	address as part of the auto configuration.</para>

      <para>For further information on the structure of IPv6 addresses
	see <ulink
	url="http://www.ietf.org/rfc/rfc3513.txt">RFC3513</ulink>.</para>
    </sect2>

    <sect2>
      <title>Getting Connected</title>

      <para>Currently there are four ways to connect to other IPv6 hosts and networks:</para>

      <itemizedlist>
	<listitem>
	  <para>Join the experimental 6bone</para>
	</listitem>

	<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>

      <para>Here we will talk on how to connect to the 6bone since it currently seems
	to be the most popular way.</para>

      <para>First take a look at the <ulink url="http://www.6bone.net/">6bone</ulink> site and find a 6bone connection nearest to
	you.  Write to the responsible person and with a little bit of luck you
	will be given instructions on how to set up your connection.  Usually this
	involves setting up a GRE (gif) tunnel.</para>

      <para>Here is a typical example on setting up a &man.gif.4; tunnel:</para>

      <screen>&prompt.root; <userinput>ifconfig gif0 create</userinput>
&prompt.root; <userinput>ifconfig gif0</userinput>
gif0: flags=8010&lt;POINTOPOINT,MULTICAST&gt; mtu 1280
&prompt.root; <userinput>ifconfig gif0 tunnel <replaceable>MY_IPv4_ADDR</replaceable>  <replaceable>HIS_IPv4_ADDR</replaceable></userinput>
&prompt.root; <userinput>ifconfig gif0 inet6 alias <replaceable>MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR</replaceable></userinput></screen>

      <para>Replace the capitalized words by the information you received from the
	upstream 6bone node.</para>

      <para>This establishes the tunnel.  Check if the tunnel is working by &man.ping6.8;
	'ing <hostid role="ip6addr">ff02::1%gif0</hostid>.  You should receive two ping replies.</para>

	<note><para>In case you are intrigued by the address <hostid role="ip6addr">ff02:1%gif0</hostid>, this is a
	  multicast address.  <literal>%gif0</literal> states that the multicast address at network
	  interface <devicename>gif0</devicename> is to be used.  Since we <command>ping</command> a multicast address the
	  other endpoint of the tunnel should reply as well.</para></note>

      <para>By now setting up a route to your 6bone uplink should be rather
	straightforward:</para>

      <screen>&prompt.root; <userinput>route add -inet6 default -interface gif0</userinput>
&prompt.root; <userinput>ping6 -n <replaceable>MY_UPLINK</replaceable></userinput></screen>

      <screen>&prompt.root; <userinput>traceroute6 www.jp.FreeBSD.org</userinput>
(3ffe:505:2008:1:2a0:24ff:fe57:e561) from 3ffe:8060:100::40:2, 30 hops max, 12 byte packets
     1  atnet-meta6  14.147 ms  15.499 ms  24.319 ms
     2  6bone-gw2-ATNET-NT.ipv6.tilab.com  103.408 ms  95.072 ms *
     3  3ffe:1831:0:ffff::4  138.645 ms  134.437 ms  144.257 ms
     4  3ffe:1810:0:6:290:27ff:fe79:7677  282.975 ms  278.666 ms  292.811 ms
     5  3ffe:1800:0:ff00::4  400.131 ms  396.324 ms  394.769 ms
     6  3ffe:1800:0:3:290:27ff:fe14:cdee  394.712 ms  397.19 ms  394.102 ms</screen>

      <para>This output will differ from machine to machine.  By now you should be
	able to reach the IPv6 site <ulink url="http://www.kame.net">www.kame.net</ulink>
	and see the dancing tortoise &mdash; that is if you have a IPv6 enabled browser such as
	<filename role="package">www/mozilla</filename>, <application>Konqueror</application>,
	which is part of <filename role="package">x11/kdebase3</filename>,
	or <filename role="package">www/epiphany</filename>.</para>

    </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,
	  such as the <ulink url="http://www.6bone.net/">6bone</ulink>, 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) on &os;&nbsp;5.X</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>
</chapter>

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