One of the easiest way of creating virtual network on linux is network bridging. General idea is that bridge is a logical network interface that can include transparently other interfaces (physical and virtual). Essentially, bridge is acting as a switch allowing to dynamically add and remove virtual machines with ease.

So, easy steps to get bridging to work on RedHat/Fedoras (note, that it might be a bit risky doing everything over ssh if you have no other channels of management, as the network might drop during the last steps):

1. First, install bridge-utils. This will basically install brctl utility used for creating/modifying bridges and some manuals.

These steps are general and were tested on Fedora Core 10, most probably every distribution has its own specificities to take into account.

Additional materials

• Networking with kvm and libvirt