Ticket #320: bootscripts.xml

<sect1 id="dhcpclient" xreflabel="Configuring the LFS bootscripts to support DHCP clients">
<?dbhtml filename="configdhcp.html" dir="connect"?>
<title>Configuring the LFS bootscripts to support DHCP clients</title>

<sect2><title>Config files</title>
<para><filename>/etc/sysconfig/network</filename>,
<filename>/etc/sysconfig/network-devices/ifup-eth0</filename>,
<filename>/etc/sysconfig/network-devices/ifdown-eth0</filename>,
<filename>/etc/sysconfig/network-devices/ifconfig.eth0</filename></para>
</sect2>

<sect2><title>Configuration Information</title>

<para>Note that on this and the following pages, we 
use <userinput>eth0</userinput> as the example interface.
If you want to configure a different (or more than one) interface, simply 
replace <userinput>eth0</userinput> with the interface you wish to use.</para>

<para>These instructions will convert the configuration files from LFS
(a static configuration) to a configuration using the DHCP protocol.  
Note that static and DHCP-based interfaces can co-exist on a LFS system.  To
do this, you should only make the alterations to those interfaces which 
need to support DHCP.  All of the instructions on this page are applicable
no matter which DHCP client you intend to use.</para>

<para>If the interface you intend to use as your default gateway is going to 
use DHCP, the first step is to remove the <envar>GATEWAY</envar> and
<envar>GATEWAY_IF</envar> variables 
from <filename>/etc/sysconfig/network</filename>.  This will only need to be
done once.</para>

<para><screen><userinput>cd /etc/sysconfig &amp;&amp;
cp network network.bak &amp;&amp;
sed "s/GATEWAY/# GATEWAY/" network.bak > network</userinput></screen></para>

<para>You then need to create scripts which will override the default
network scripts and provide DHCP support.  These two scripts are generic and
so for use with both DHCP clients.  First, the
<filename>ifup-eth0</filename> script:</para>

<para><screen><userinput>cat &gt; /etc/sysconfig/network-devices/ifup-eth0 &lt;&lt; "EOF" </userinput>
#!/bin/sh

source /etc/sysconfig/rc || exit
source $rc_functions || exit
source $network_devices/ifconfig.eth0 || exit

echo "Bringing up the eth0 interface..."
modprobe eth0
loadproc $DHCP_PROG $DHCP_START

echo "Setting up the /etc/hosts file..."
if [ $(basename $DHCP_PROG) == "dhcpcd" ]
then
    source /var/lib/dhcpc/dhcpcd-eth0.info

else
    if [ $(basename $DHCP_PROG) == "dhclient" ]
    then
        IPADDR=$(sed -n 's/;//;/fixed-address/s/.* //p' \
             /var/state/dhcp/dhclient.leases |tail -n1)

    else
        IPADDR=999.999.999.999
    fi

fi

sed "s/0.0.0.0/$IPADDR/" \
    /etc/sysconfig/network-devices/hosts.dhcp &gt; /etc/hosts
evaluate_retval

<userinput>EOF</userinput></screen></para>

<para>Then the <filename>ifdown-eth0</filename> script:</para>

<para><screen><userinput>cat &gt; /etc/sysconfig/network-devices/ifdown-eth0 &lt;&lt; "EOF" </userinput>
#!/bin/sh

source /etc/sysconfig/rc || exit
source $rc_functions || exit
source $network_devices/ifconfig.eth0 || exit

echo "Bringing down the eth0 interface..."
$DHCP_PROG $DHCP_STOP
evaluate_retval
<userinput>EOF</userinput></screen></para>

<para>Next, we need to make these scripts executable:</para>

<para><screen><userinput>chmod 755 /etc/sysconfig/network-devices/ifup-eth0 &amp;&amp;
chmod 755 /etc/sysconfig/network-devices/ifdown-eth0</userinput></screen></para>

<para>Make a backup copy of your /etc/hosts file and one to source for the scripts:</para>

<para><screen><userinput>cp /etc/hosts /etc/hosts.bak &amp;&amp;
cp /etc/hosts /etc/sysconfig/network-devices/hosts.dhcp</userinput></screen></para>

<para>Finally, edit the <userinput>/etc/sysconfig/network-devices/hosts.dhcp</userinput>, and replace
the existing IP address associated with the FQDN with <userinput>0.0.0.0</userinput>.</para>

</sect2>

</sect1>