TSPU: Russia’s Decentralized Censorship System

Diwen Xue, Benjamin Mixon-Baca, S. S. Valdik, Anna Ablove, Beau Kujath, Jedidiah R. Crandall, Roya Ensafi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


Russia’s Sovereign RuNet was designed to build a Russian national firewall. Previous anecdotes and isolated events in the past two years reflected centrally coordinated censorship behaviors across multiple ISPs, suggesting the deployment of “special equipment” in networks, colloquially known as “TSPU”. Despite the TSPU comprising a critical part of the technical stack of RuNet, very little is known about its design, its capabilities, or the extent of its deployment. In this paper, we develop novel techniques and run in-country and remote measurements to discover the how, what, and where of TSPU’s interference with users’ Internet traffic. We identify different types of blocking mechanisms triggered by SNI, IP, and QUIC, and we find the TSPU to be in-path and stateful, and possesses unique state-management characteristics. Using fragmentation behaviors as fingerprints, we identify over one million endpoints in Russia from 650 ASes that are behind TSPU devices and find that 70% of them are at most two hops away from the end IP. Considering that TSPU devices progressed from ideation to deployment in three years, we fear that the emerging TSPU architecture may become a blueprint for other countries with similar network topology.

Original languageEnglish (US)
Title of host publicationIMC 2022 - Proceedings of the 2022 ACM Internet Measurement Conference
PublisherAssociation for Computing Machinery
Number of pages16
ISBN (Electronic)9781450392594
StatePublished - Oct 25 2022
Event22nd ACM Internet Measurement Conference, IMC 2022 - Nice, France
Duration: Oct 25 2022Oct 27 2022

Publication series

NameProceedings of the ACM SIGCOMM Internet Measurement Conference, IMC


Conference22nd ACM Internet Measurement Conference, IMC 2022


  • Censorship
  • Interception
  • Measurement
  • Russia

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications


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