Abstract:
Internet censorship is increasing worldwide. To allow citizens of censoring countries to access the free internet, numerous circumvention tools have been developed. This thesis focuses on tools that circumvent DPI-based censorship by manipulating the user’s internet traffic. We analyze and compare 27 of these tools to identify the ones that are most useful. Included are tools for general use on a computer, Android tools, and Tor pluggable transports. We categorize them based on the circumvention techniques they implement. Ten of these tools are tested regarding their functional correctness, and Linux versions of the tools are installed on machines located in Russia and China to test their effectiveness against the censorship measures. We find that most censorship circumvention tools provide the functionality they advertise and effectively circumvent censorship in Russia. In particular, we conclude that the most capable and popular tools are GoodbyeDPI, ByeDPI (including the Android version), zapret, and Snowflake. ByeDPI is the best tool overall when considering platform availability, implemented techniques, correctness, effectiveness against censorship, and the possibility to use the tool without root privileges. However, the effectiveness of the tools is opposed by questionable usability and missing guidance for users which tool to install. Therefore, we argue for an extended usability research in the future.