Changes between Initial Version and Version 14 of Ticket #21014

Dec 18, 2016, 7:11:08 PM (4 years ago)

dgoulet points to this Turkey Blocks article: They tested vanilla, obfs3, and obfs4, and also noted that the apparent rise in the metrics graphs may be caused by miscounting. I append some quotations.

The Turkey Blocks internet censorship watchdog has identified and verified that restrictions on the Tor anonymity network and Tor Browser are now in effect throughout Turkey.

Other circumvention methods, including Tor’s bridged modes built to evade similar restrictions imposed by the regime in Syria, as well as custom VPN deployments, continue to remain available to technically skilled users in the short-term.

Turkey Blocks finds that the Tor direct access mode is now restricted for most internet users throughout the country; Tor usage via bridges including obfs3 and obfs4 remains viable, although we see indications that obfs3 is being downgraded by some service providers with scope for similar on restrictions obfs4. The restrictions are being implemented in tandem with apparent degradation of commercial VPN service traffic.

Direct Tor access restrictions started around 12 December 2016. Tor’s direct mode is now entirely unusable via providers TTNet and UyduNet on the residential broadband connections we tested. Deep Packet Inspection (DPI) is likely used to disrupt the connection phase, which stalls around the 10% mark.

Connection is possible using obfs3 and obfs4 Tor bridges with both providers. While obfs4 is effective across all configurations, obfs3 intermittently fails with TTNet.

Where we expected a fall in usage corresponding to widespread reports of failure to access the Tor network, charts instead show a huge increase in Tor usage over the same period.

During tests we saw over a hundred connection attempts associated with a single user connection request, leading us to favour the theory Tor metrics have incorrectly counted these failed attempts in their overall usage tally.


  • Ticket #21014

    • Property Component changed from Core Tor/Tor to Metrics/Censorship analysis
    • Property Summary changed from TR is blocking Tor connections to Turkey blocking of direct connections, 2016-12-12
    • Property Owner set to metrics-team
    • Property Keywords censorship block tr Turkey UX added
    • Property Type changed from defect to task
  • Ticket #21014 – Description

    initial v14  
     1Turkey Blocks article:
    13After getting some reports on twitter about Tor being blocked in Turkey and some chat on IRC, <bypassemall> aka <trdpi> aka <kzdpi> ran some tests and found some interesting information about how Turkey is blocking vanilla Tor connections. I paste their findings here: