Network lab with QEMU

To experiment with network stuff, I was using UML-based network labs. Many alternatives exist, like GNS3, Netkit, Marionnet or Cloonix. All of them are great viable solutions but I still prefer to stick to my minimal home-made solution with UML virtual machines. Here is why: I didn’t want to use disk images. They take a lot of space and they have to be maintained. They also become cluttered, especially if you try to reuse them across several labs. They are also difficult to share. I want to be able to access my home directory. It contains the important configuration files related to the lab and I can put them in the right place thanks to symbolic links when the lab starts. It also makes exchanging files with the lab quite easy. I don’t want to boot a complete system. This allows me to be cheap on memory and each virtual system should boot in a few seconds. The use of UML had some drawbacks: It may be buggy. For example, it is currently not possible to use gdbserver inside UML without…