If you searching tutorial on how to create bridged interface, maybe you’ll refer to Ubuntu documentation. Honestly, it’s hard. Maybe it works. But in my case, it doesn’t.
Nevermind, here I give you guide on how to do it in easier way.
sudo apt-get install bridge-utils
It will create new interface called br0
sudo brctl addbr br0
sudo brctl addif br0 eth0 eth1
You can restart you interface by this command:
sudo /etc/init.d/networking restart
You also can setup bridged interface automatically on boot by adding this to /etc/network/interfaces:
iface br0 inet static
bridge_ports eth0 eth1
The important param is bridge_ports, which assign the ethernet port to bridge interface.