Blocking Proxy Sites

Does anyone have any thoughts (or solutions!) for how to
block proxy sites?
We've had a rash of patrons using proxies to bypass our
filtering software
(which doesn't automatically block proxies- we use
ContentProtect).    Any
ideas would be most appreciated.

Thanks,
Michele
_______________________________________________
Web4lib mailing list
Web4libwebjunction.org
http://lists.we
bjunction.org/web4lib/
AdmID:B59962FBB92E4EFE588061F8D172DB99
_______________________________________________
Web4lib mailing list
Web4libwebjunction.org
http://lists.we
bjunction.org/web4lib/