Bridging setup on bootup on Debian/Ubuntu

The following should pretty much work on any Debian based systems. It also requires the bridge module and bridge-utils packages.

/etc/network/interfaces

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp

auto br0
iface br0 inet static
        address 192.168.1.1
        netmask 255.255.255.0
        broadcast 192.168.1.255
        pre-up ifconfig eth1 down
        pre-up ifconfig eth2 down
        pre-up brctl addbr br0
        pre-up brctl addif br0 eth1 eth2
        pre-up ifconfig eth1 0.0.0.0 up
        pre-up ifconfig eth2 0.0.0.0 up
        post-down ifconfig eth1 down
        post-down ifconfig eth2 down
        post-down brctl delif br0 eth1 eth2
        post-down brctl delbr br0