What's with you guys? The young Mitnick would be ashamed...
Have some fun with him. As long as he isn't doing anything illegal, or use a lot of bandwidth with torrents, keep him on the network.
Run Nmap,
find his IP,
MITM with ettercap.
Write a filter that swaps every image with "goatse.jpg" see how long he keeps using the network .
????
PROFIT!
Be creative, I thought having fun with guys like this was standard stuff. If he keeps using it, add more filters once a day, redirect him from google to klingon google.
I know this is a late reply, but C'MON! Hacking is about having fun!
-Jez