Victor Stinner of INL worked a little bit on fuzzing. He wrote a python client to fuzz programs input. And he has been damn successful. He even wrote a little fuzz server to discover more crashes...

Fuzzing is the art of altering data, in anyway. It can be random data, as this can be a hard science of understanding how files work and are read. It usually remain simple. Everyone can remember bugs where the packet length field in a packet was shorter than the packet itself and produced crashes.

People don't pay enough attention to this problem. If you want to be scared a bit from a two weeks of work, please consult Victor's crash list (take children off the screen before clicking).

VoIP people, don't worry. There is already the protos project doing research in this area. Look at routines they wrote for SIP. 4527 test cases for SIP only. Enjoy!