Detecting Anonymising Proxy Usage on the Internet

Anonymising proxies are a growing problem for organisations as more people become aware of their capabilities. These proxy sites enable users to bypass the network’s filtering system leaving the network open to banned content and harmful threats. Network administrators do try to block these online proxy sites, but with a growing number of new sites created, this task is not a trivial one. Many existing solutions rely almost entirely on Access Control Lists, which blacklist undesirable websites; the end result being that many users learn that anonymous proxies allow them to easily bypass this filtering. While Access Control Lists serve a purpose, there are lots of difficulties especially in detecting if users are circumventing the policies and Access Control Lists. One possible solution is to focus on detecting access to anonymous proxies. This paper outlines procedures required to discover anonymous proxies on the Internet.