作者：Hal Roberts, Ethan Zuckerman, Jillian York, Rob Faris, John Palfrey
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. But every type of circumvention tool provides the same basic functionality ― proxying user connections to provide access to otherwise blocked sites. In the following report, we 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 ― notably Freegate, Ultrasurf, Tor, and Hotspot Shield ― we 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, we 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.
- We estimate that no more than 3% of Internet users in countries that engage in substantial filtering use circumvention tools. The actual number is likely considerably less.
- Many more users use simple web proxies than use either blocking-resistant tools or VPN services. Of the 11 tools with at least 250,000 unique monthly monthly users, 3 are blocking-resistant tools, 1 is a VPN service, and 7 are simple web proxies.
- When users search for proxy and circumvention related terms in filtering countries, they overwhelmingly search for generic proxy terms like "proxy," and those terms overwhelmingly return either simple web proxies or sites that list simple web proxies and HTTP/SOCKS proxies, not more sophisticated tools.