Crowds

A topic closely related to web filtering is anonymous web browsing. Filtering systems provide some anonymous web browsing features by filtering Cookie, Referer, and User-Agent headers. However, an important feature that users need to hide their identity on the web is the ability to hide their IP address from remote web servers. Since filtering systems act as a gateway between the browser and server, web servers receive requests from the filtering system server IP address, not the web browser. This allows the user to hide their identity behind the filtering system. It is common though for users to run the filtering system and web browser on the same computer. In this case users cannot hide their IP address since all requests will be seen as coming from their personal computer. It is still possible for users to conceal their IP address. One method is to use IP address spoofing which is difficult and not always possible. Another method is to use Crowds.

Crowds is a system developed by AT&T to protect user privacy while web browsing. Named for the idea of blending into a crowd, Crowds operates by grouping a wide variety of users together to form a crowd of users. Each user in the crowd has the ability to submit requests that can be issued by any of the other crowd members. Because of this, web servers are unable to learn the true IP address where a request originated since the request can come from any one of the crowd members. The only downsides to the Crowds system are an artifact of how the system is designed. Members within the crowd do have the ability to see other crowd member requests. The system is designed to also make it difficult for crowd members to determine where requests originate, but the member chosen to handle a particular request can view all the request data. Users of the Crowds system may also not like the fact that their own computer can be used by other members to submit requests. Aside from those problems, Crowds is a very powerful anonymous web browsing system.