OK, I'm running libvirt on my server, I have only one interface. In order to use the public IP in my VM I need to set up a bridge, everything OK so far.. But I don't want to setup an IP address on the bridge interface. When I leave the bridge without IP and set IP on eth0, it won't work..
Can someone explain me why?
That's how bridges work.
When you bridge devices together, the networking configuration applies to the bridge since it is representing all of the connected devices.
Therefore you must apply the network settings to the bridge, and not to any of its constituent devices.
That's just the way it works.
eth0 is part of the bridge, it is no longer it's own interface and the bridge interface 'owns' it. So to have an address, you need to configure it on the bridge, not on eth0.
