Don't worry! It's only stuff...

#!/bin/bash
 
# backup original network config
mv /etc/network/interfaces /etc/network/interfaces.org
 
# configure network bridge for xen
cat <<EOF> /etc/network/interfaces
auto lo
iface lo inet loopback
 
# eth0 (internal lan)
auto eth0 eth1 xenbr1
iface eth0 inet static
        address 192.168.1.111
        netmask 255.255.255.0
        network 192.168.1.0
        broadcast 192.168.1.255
        gateway 192.168.1.5
        #post-up ethtool -K eth0 tx off
 
# eth1 (DSL)
iface eth1 inet manual
        up ifconfig eth1 0.0.0.0 promisc up
 
# xenbr1 (bridge between second nic and virtual firewall)
iface xenbr1 inet manual
        up ifconfig xenbr1 0.0.0.0 up
        bridge_ports eth1
        bridge_fd 1
        bridge_stp off
        bridge_hello 1
        down ifconfig xenbr1 down
EOF