How exactly Bess filter work?

I have been researching the requests HTTP 1.1 and 1.0 and Bess seems to be working inconsistently. If you just block the IP address, then, parents must work, but Bess is not to be able to lock individual applications on a server, such as pages individual in Wikipedia (obviously would not object to the whole crowd of Wikipedia). Therefore, it should be blocked by URL. However, if you block by URL, then proxies should not be able to dispense with it, since the only difference between a proxy request and a joint petition is whether or not the host name is included in the header. That could be a big enough difference to confuse Bess, but you'd think the writers have anticipated or updated it after all began to use proxies. If it helps at all, we traceroute to my school before and everything goes through the school server and the server of the Board so there is no way it is actually bypassing the filter. What's happening?

Sorry old fruit, I can not help, I hope someone of a higher intellect than answers

SMTPGuard / Spam-cat