brctl addbr br0
brctl addif br0 eth0
brctl addif br0 eth1
brctl addif br0 eth2
auto lo
 iface lo inet loopback
auto eth0
 iface eth0 inet static
 address 0.0.0.0
auto eth1
 iface eth1 inet static
 address 0.0.0.0
auto eth2
 iface eth2 inet static
 address 0.0.0.0
auto br0
 iface br0 inet dhcp