Bash Bomb

So my buddy Greg pointed me to what he called a ‘bash bomb’.  It looks like:

:(){ :|:& };:

Anyway, all it does is recursively fork.  http://www.cyberciti.biz/faq/understanding-bash-fork-bomb/ gives a good explanation.  I do like it, because of its simplicity and obscurity. I have to deal with recursively forking things all the time (thanks operating system class with students experimenting with fork for the first time).

A simple pam hard limit on the number of processes can mitigate against this.  Put it in /etc/security/limits.conf.

My applicable limits are (fairly liberal):

*               soft    nproc           225
*               hard    nproc          300

So far, nothing has crashed the system with these, but I keep having to tweak them, so I may restrict them further in the future.