A while ago I needed to restrict a page to only on campus users - which led to this small script in PHP:
The script checks the remote users IP and determines if it is within the set of allowed IP ranges. Most people just check for an address beginning with 129.93, but the university has some extension offices using other IP ranges outside of that.
The network masks for UNL IP addresses are:
I will update this if I hear that anything has changed.
I figured this might be useful for some others to use.