The Tor Censorship Arms Race: The Next Chapter

Conference:  Defcon 27



The presentation discusses the importance of privacy and security on the internet, particularly in relation to surveillance and censorship infrastructure. It highlights the need for safe tools that do not enable governments to harm people and the role of Tor in achieving this goal.
  • Misconfigured FTP server in Syria with gigabytes of blue code logs found by Anonymous from Telecomix
  • Blue code sold to Dubai and resold to Syria, despite Syria being on the list of places American companies are not supposed to sell to
  • Blue code lied about their involvement and cooperation in the investigation
  • Symantec now runs the surveillance and censorship infrastructure in Syria
  • Discussion on the need for safe tools that do not enable governments to harm people
  • Importance of educating people about Tor and privacy on the internet
  • Running a bug smash fund to fix bugs and make Tor more reliable
The speaker had an interesting meeting with the person in charge of the Tunisia internet after their revolution. He admitted to using Smart Filter and paying a million dollars a year for it, but also expressed frustration at the amount of money being spent on censorship instead of food for the country. The Smart Filter operation was outsourced to a foreign company, which the speaker assumes is in France.


Tor is a free-software anonymizing network that helps people around the world use the Internet in safety. But who cares how good Tor's privacy is, if your government prevents you from reaching the Tor network? In the beginning, some countries filtered torproject.org by DNS (so we made website mirrors and an email autoresponder for downloading Tor), and then some countries blocked Tor relays by IP address (so we developed bridges, which are essentially unlisted relays), and then some countries blocked Tor traffic by Deep Packet Inspection (so we developed pluggable transports to transform Tor flows into benign-looking traffic). Then things got weird, with China's nationwide active probing infrastructure to enumerate bridges, with Amazon rolling over to Russia's threats when Telegram used "domain fronting" to get around blocking, with Turkey blocking Tor traffic by DPI in more subtle ways, with Venezuela and Ethiopia and Iran trying new tricks, and more. In this talk I'll get you up to speed on all the ways governments have tried to block Tor, walk through our upcoming steps to stay ahead of the arms race, and give you some new—easier—ways that let you help censored users reach the internet safely.