The OpenNet Initiative has documented network filtering of the Internet by national governments 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. First, even though much of the media attention on circumvention tools has been given to a handful of tools, they find that these tools represent only a small portion of overall circumvention usage and that the attention paid to these tools has been disproportionate to their usage, especially when compared to the more widely used simple web proxies. Second, even when including the more widely-used simple web proxies, the authors find that overall usage of circumvention tools is still very small in proportion to the number of Internet users in countries with substantial national Internet filtering.