Proxy abuse is an increasingly pervasive problem in schools. It only takes one anonymous proxy to put a gaping hole in your network security. Using a web filtering solution that doesn't block proxies is the equivalent of putting a big bolt on your front door but leaving the back door wide open. Anonymous proxies allow users to browse the web without disclosing their online activities to filtering solutions. There are millions of these anonymizers in existence with miscreants developing new types faster than security vendors can detect and block them. Proxy abuse can only be prevented with intelligent filtering solutions.