Use The Command Line, Luke

If Luke Skywalker were a security administrator his most powerful tools might be command line tools. Over at EthicalHacker.net you'll find a hacking challenge, "Star Hacks, Episode V: The Empire Hacks Back " where you need to figure out how to terminate a bunch of processes, some of which spawn new processes when they are terminated. It's sort of like trying to kill Medusa, except with a Star Wars theme. The prize for winning the challenge is a copy of the book, Counter Hacker Reloaded.