source: clfs-embedded/BOOK/bootscripts/common/network.xml

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;
]>

<sect1 id="ch-scripts-network">
  <?dbhtml filename="network.html"?>

  <title>Configuring the network Script</title>

  <indexterm zone="ch-scripts-network">
    <primary sortas="d-network">network</primary>
  <secondary>configuring</secondary></indexterm>

  <sect2>
    <title>Creating Network Interface Configuration Files</title>

    <para>Which interfaces are brought up and down by the network utilities
      depends on the files and directories in the
      <filename class="directory">/etc/network</filename> directory.  The
      <filename>interfaces</filename> file should contain a
      description of the interfaces, as done by Debian, and each of the
      directories contain scripts for actions to perform on each type of network
      event.</para>

    <para>The following command creates the required directories and the
      <filename>interfaces</filename> file, assuming DHCP will be used for
      eth0:</para>

<screen><userinput>mkdir -pv ${CLFS}/targetfs/etc/network/if-{post-{up,down},pre-{up,down},up,down}.d
mkdir -pv ${CLFS}/targetfs/usr/share/udhcpc

cat &gt; ${CLFS}/targetfs/etc/network/interfaces &lt;&lt; "EOF"
<literal>auto eth0
iface eth0 inet dhcp</literal>
EOF</userinput></screen>

    <para>For DHCP to work properly with udhcpc, the BusyBox dhcp client, a
      configuration script is needed.  Create a simple script to assign the
      provided DHCP address and update <filename>/etc/resolv.conf</filename>:</para>

<screen><userinput>cat &gt; ${CLFS}/targetfs/usr/share/udhcpc/default.script &lt;&lt; "EOF"
<literal>#!/bin/sh
# udhcpc Interface Configuration
# Based on http://lists.debian.org/debian-boot/2002/11/msg00500.html
# udhcpc script edited by Tim Riker &lt;Tim@Rikers.org&gt;

[ -z "$1" ] &amp;&amp; echo "Error: should be called from udhcpc" &amp;&amp; exit 1

RESOLV_CONF="/etc/resolv.conf"
[ -n "$broadcast" ] &amp;&amp; BROADCAST="broadcast $broadcast"
[ -n "$subnet" ] &amp;&amp; NETMASK="netmask $subnet"

case "$1" in
        deconfig)
                /sbin/ifconfig $interface 0.0.0.0
                ;;

        renew|bound)
                /sbin/ifconfig $interface $ip $BROADCAST $NETMASK

                if [ -n "$router" ] ; then
                        while route del default gw 0.0.0.0 dev $interface ; do
                                true
                        done

                        for i in $router ; do
                                route add default gw $i dev $interface
                        done
                fi

                echo -n &gt; $RESOLV_CONF
                [ -n "$domain" ] &amp;&amp; echo search $domain &gt;&gt; $RESOLV_CONF
                for i in $dns ; do
                        echo nameserver $i &gt;&gt; $RESOLV_CONF
                done
                ;;
esac

exit 0
</literal>EOF

chmod +x ${CLFS}/targetfs/usr/share/udhcpc/default.script</userinput></screen>

  </sect2>

</sect1>