here is a challenge. I realize it's linux but I think this is the right group to ask anyway; I think you'll appreciate the humor in it. So far few I have talked to have gotten it.
There is a file, called /bin/bash. You are allowed to do this as root. cp this file to /tmp. Do something to it to make it so that, when you are not root, you can run the file in /tmp and get a root shell. Don't assume the obvious. And please don't post "that's trivial" until you have actually done it. ron
