in over forty countries worldwide. Countries use this network filtering as one of many methods to control the flow of online content that is objectionable to the filtering governments for social, political, and security reasons. Filtering is particularly appealing to governments as it allows them to control content not published within their national borders.
Circumvention tools allow users to bypass Internet filtering to access content otherwise blocked by governments, workplaces, schools, or even the blocked sites themselves. There are a number of different types of these tools: blocking-resistant tools, simple web proxies, virtual private network (VPN) services, and open HTTP/SOCKS proxies.
In this report, the authors use a variety of methods to evaluate the usage of the first three of these four types of tools to test two hypotheses.