Re:Moral of the story (Score 5, Informative)

Unfortunately, you need to provide your MAC to the university to register for the network connection in the first place. So they already have it.

Actually, that's only partly true. UW networks that the average Badger (i.e. likely not to know how or why to spoof their MAC) would plug into are in one of three flavors.

ResNet (wired in rooms in older dorms and wireless in common dining areas and new residence halls). ResNet requires every computer connected to it be registered with a campus NetId (http://www.housing.wisc.edu/resnet/netreg.php). Those registrations are attached to MAC addresses so that a device may move around ResNet without having to register to every new jack it encounters. Also, so that a quarantined machine stays in the quarantine subnet until it's cleaned. These registrations expire every 120 days, and IP leases roll faster than that, but the address doesn't change very often as you tend to get the same IP on a renew.

DoIT (Division of Information Technology) Wireless, called UWNet, http://www.doit.wisc.edu/network/wireless/ is the main campus wireless and is in classroom buildings, the unions and libraries. A NetId is also required to authenticate each time one connects. These IP addresses probably move around faster. I'm sure DoIT complies with whatever policy is in place for keeping these records, but who knows how long that is.

Wired library computers. These are the working girls of the campus network. One needs a student ID number to access them, but finding a lost card or snooping for a number is not hard. Nor is guessing the 1 digit activation code that needs to be added on the end to authenticate. Again, who knows how long these records are kept.

Also, students in the res halls tend to use a certain jukebox program (comes with a popular music player) that advertises its shared library only within that hall's subnet - so no one external to that subnet is able to see that traffic.

Long way around to saying these John and Jane Does are going to be a bit hard to pin down. Should be fun to watch.