Linux From Scratch
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# Creating the /etc/init.d/ethnet script

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

A new file `/etc/init.d/ethnet` is created containing the following:

`cat > /etc/init.d/ethnet << "EOF"`
#!/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 $(ls /etc/sysconfig/network-scripts/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 eth0 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 $(ls /etc/sysconfig/network-scripts/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
`EOF`

## Adding default gateway to /etc/sysconfig/network

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

`cat >> /etc/sysconfig/network << "EOF"`
GATEWAY=192.168.1.2
GATEWAY_IF=eth0
`EOF`

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.

## Creating NIC configuration files

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

First the network-scripts directory is created by running:

> `mkdir /etc/sysconfig/network-scripts`

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

`cat > /etc/sysconfig/network-scripts/ifcfg-eth0 << EOF`
ONBOOT=yes
DEVICE=eth0
IP=192.168.1.1
NETMASK=255.255.255.0
BROADCAST=192.168.1.255
`EOF`

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.

## Setting up permissions and symlink

The proper file permissions and the necessary symlinks are set or created by running the following commands:

> `cd /etc/init.d &&`
> `chmod 754 ethnet &&`
> `cd ../rc0.d &&`
> `ln -s ../init.d/ethnet K800ethnet &&`
> `cd ../rc1.d &&`
> `ln -s ../init.d/ethnet K800ethnet &&`
> `cd ../rc2.d &&`
> `ln -s ../init.d/ethnet K800ethnet &&`
> `cd ../rc3.d &&`
> `ln -s ../init.d/ethnet S200ethnet &&`
> `cd ../rc4.d &&`
> `ln -s ../init.d/ethnet S200ethnet &&`
> `cd ../rc5.d &&`
> `ln -s ../init.d/ethnet S200ethnet &&`
> `cd ../rc6.d &&`
> `ln -s ../init.d/ethnet K800ethnet &&`

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