auto br0
iface br0 inet static address <your_ip_address>
  netmask <your_net_mask>
  network <your_network>
  broadcast <your_network_broadcast_address>
  gateway <your_default_gateway>
  pre-up ifconfig eth0 down
  pre-up brctl addbr br0
  pre-up brctl addif br0 eth0
  pre-up ifconfig eth0 up
  post-down ifconfig eth0 down
  post-down brctl delif br0 eth0