My last KVM blog entry showed how to install all the prereqs and do the initial install of the virtual machine to host your IDS toy instances.

To really start playing we'll need networking of course.
I'm not going into the details explaining every single line of config, much better explanations are already written on the web. But I'll try to give a reasonable overview.

To connect the VMs both to the outer world and between themselves we'll need a kind of virtual switch running on host machine and "wire" network interfaces in VMs to it.
We'll use virtual TUN/TAP network interface and promote it to the virtual switch using VDE utility.

Motivated by article on using Xen and Informix on Developerworks (http://www.ibm.com/developerworks/db2/library/techarticle/dm-0807fuerderer/index.html) and by Eric's comment I'll try to give a similar step-by-step explanation on how to setup KVM virtual machines on Linux box if you need a playground to test new features or proof-of-concept projects. Originally, I commented it seems easier to setup KVM than Xen, and hopefully I'll show it is. Except maybe for one bit :) And that's networking. More on that later. I'm assuming the next hardware configuration: