As sentiment that internet freedom is increasingly being threatened worldwide is on the rise, details on the extent of how censorship is conducted at a technical level is often unavailable. At the USENIX Free and Open Communications on the Internet (FOCI) workshop today in Washington, D.C. two papers provided this information in two countries. The first by Zubair Nabi focused on increases in Internet Censorship efforts in Pakistan, and the second by Simurgh Aryan, Homa Aryan, and J. Alex Halderman examined in detail the rigorous censorship regimes present in Iran. Both papers can be found here and both illustrate a disturbing trend in state repression of information.
Nabi’s paper highlights the timeline of implementation of censorship activities in Pakistan dating back to 2006 and focuses in particular on advances in censorship technologies in recent years. They use a variety of methods including DNS injection, HTTP redirection, and DNS blockages at the HTTP level. While running tests on the censorship techniques of the Pakistan Telecommunications Authority (PTA), they also by chance discovered a new censorship page redirecting traffic intended for YouTube. They subsequently found that attempts to censor YouTube content in Pakistan has adverse effects on other Google applications. Nabi finds that most of the technical means of censorship are easily circumvented using various VPN and proxy tools available.
The second paper, by Aryan, Aryan, and Halderman provides an in-depth examination of Iranian censorship tools and techniques and also attempts to provide a topographical mapping of internet censorship across the country. This paper illustrates a highly organized and dynamic censorship approach by Iran and provides detailed analysis of censorship across hundreds of websites using Alexa’s top 500 websites. They further refine their data down to content categories including political, cultural, adult, etc. The provide statistics on the number and types of pages blocked. Among the tools used to censor the Internet the authors identify: broadband speed limitations, DNS redirection, HTTP host and keyword filtering, connection throttling. They find prevalent censorship across content types with a particularly developed level of censorship focused on adult content.
Both of these papers are valuable contributions to the literature on censorship and both offer a necessary perspective on what human and democracy rights activists are facing on a daily basis. As we and other organizations continue to work with civic activists and organizations, staying cognizant of the means used to monitor and censor their activities is of the utmost importance. Continued research in the field of internet censorship can help shed light on such practices and thus better inform methods to counteract them.