lfs-book/chapter07/ethnet.xml

<sect1 id="ch07-ethnet">
<title>Creating the /etc/init.d/ethnet script</title>

<para>
This section only applies if a user is going to configure a network card.
If not, this section can be skipped.
</para>

<para>
A new file <filename>/etc/init.d/ethnet</filename> is created containing the
following:
</para>

<para>
<screen>
<userinput>cat &gt; /etc/init.d/ethnet &lt;&lt; "EOF"</userinput>
#!/bin/sh
# Begin /etc/init.d/ethnet
#
# Main script by Gerard Beekmans - gerard@linuxfromscratch.org
# GATEWAY check by Jean-François Le Ray - jfleray@club-internet.fr
# "Specify which IF to use to reach default GATEWAY" by 
#     Graham Cantin - gcantin@pacbell.net
#

#
# Include the functions declared in the /etc/init.d/functions file
# and the variables from the /etc/sysconfig/network file.
#

source /etc/init.d/functions
source /etc/sysconfig/network

case "$1" in
        start)

#
# Obtain all the network card configuration files
#

        for interface in $(/bin/ls /etc/sysconfig/nic-config/ifcfg* | \
            grep -v ifcfg-lo)
        do
#
# Load the variables from that file
#

            source $interface
#
# If the ONBOOT variable is set to yes, process this file and bring the
# interface up.
#

            if [ "$ONBOOT" == yes ]
            then
                echo -n "Bringing up the $DEVICE interface..."
                /sbin/ifconfig $DEVICE $IP broadcast $BROADCAST \
                    netmask $NETMASK
                evaluate_retval
            fi
        done

#
# If the /etc/sysconfig/network file contains a GATEWAY variable, set
# the default gateway and the interface through which the default
# gateway can be reached.
#

            if [ "$GATEWAY" != "" ]; then
                echo -n "Setting up routing for $GATEWAY_IF interface..."
                /sbin/route add default gateway $GATEWAY \
                        metric 1 dev $GATEWAY_IF
                evaluate_retval
            fi
                ;;

        stop)

#
# Obtain all the network card configuration files
#

        for interface in $(/bin/ls /etc/sysconfig/nic-config/ifcfg* | \
            grep -v ifcfg-lo)
        do
#
# Load the variables from that file
#

            source $interface
#
# If the ONBOOT variable is set, process the file and bring the
# interface down
#

            if [ $ONBOOT == yes ]
            then
                echo -n "Bringing down the $DEVICE interface..."
                /sbin/ifconfig $DEVICE down
                evaluate_retval
            fi
        done
                ;;

        restart)
                $0 stop
                sleep 1
                $0 start
                ;;
        *)
                echo "Usage: $0 {start|stop|restart}"
                exit 1
                ;;
esac

# End /etc/init.d/ethnet
<userinput>EOF</userinput>
</screen>
</para>

<sect2>
<title>Adding default gateway to /etc/sysconfig/network</title>

<para>
If a default gateway is required to be setup, the following command does that:
</para>

<para>
<screen>
<userinput>cat &gt;&gt; /etc/sysconfig/network &lt;&lt; "EOF"</userinput>
GATEWAY=192.168.1.2
GATEWAY_IF=eth0
<userinput>EOF</userinput>
</screen>
</para>

<para>
GATEWAY and GATEWAY_IF need to be changed to match the network setup.
GATEWAY contains the address of the default gateway, and GATEWAY_IF
contains the network interface through which that default gateway can
be reached.
</para>

</sect2>

<sect2>
<title>Creating NIC configuration files</title>

<para>
Which interfaces are brought up and down by the ethnet script depends on
the files in the /etc/sysconfig/nic-config directory. This
directory should contain files in the form of ifcfg-x where x is an
identification number (or whatever a user named it).
</para>

<para>
First the nic-config directory is created by running:
</para>

<para>
<screen>
<userinput>mkdir /etc/sysconfig/nic-config</userinput>
</screen>
</para>

<para>

Now, new files are created in that directory containing the following.
This creates a sample file ifcfg-eth0:
</para>

<para>
<screen>
<userinput>cat &gt; /etc/sysconfig/nic-config/ifcfg-eth0 &lt;&lt; "EOF"</userinput>
ONBOOT=yes
DEVICE=eth0
IP=192.168.1.1
NETMASK=255.255.255.0
BROADCAST=192.168.1.255
<userinput>EOF</userinput>
</screen>
</para>

<para>
Of course, the values of those four variables have to be changed 
in every file to
match the proper setup. Usually NETMASK and BROADCAST will remain the
same, just the DEVICE IP variables will change per network interface. If 
the ONBOOT variable is set to yes, the ethnet script will bring it up 
during boot up of the system. If set to anything else but yes it will be 
ignored by the ethnet script and thus not brought up.
</para>

</sect2>

</sect1>