TSG ships a built-in periodic-report feature ("Tiangou Secure Gateway" branded PDF exports) that breaks down traffic per major global platform — observed for YouTube, Facebook, Instagram, Netflix, Snapchat, BBC, and Bigo across six independent report exports — via "SNI Report of Overseas APP" and "Server IP and Location of Overseas APP" tables, giving operators granular, per-platform SNI- and IP-geolocation-based usage visibility as a standard dashboard capability, not just blocking.
Tiangou Secure Gateway Youtube SNI Table
Defense implications
- SNI-based per-platform reporting is a default TSG feature; any circumvention transport that leaves a distinguishable SNI value (own domain, distinctive fronting domain reused at scale) will show up as its own line item in routine operator reporting, not just get blocked silently.
Related findings
A dedicated internal "运营商前端分析团队" (Carrier Front-end Analysis Team) produces weekly, carrier-specific traffic-analysis reports explicitly titled "新疆移动流量分析报告" (Xinjiang Mobile Traffic Analysis Report) and "新疆联通流量分析报告" (Xinjiang Unicom Traffic Analysis Report), with instances dated from at least July 2022 through March 2024. One instance (Xinjiang Mobile, 2023-05-15) reports total carrier bandwidth of 4.4Tbps (1Tbps access bandwidth), 27.34PB of weekly throughput, 123 distinct identified application-layer protocols, and a section (4.1, pages 17+) explicitly tracking server IP/location for 28 named overseas apps (BBC, Discord, ESPN, Facebook, Gmail, Google, Hulu, Instagram, Netflix, Reddit, Skype, Telegram, Twitter, Uber, WhatsApp, Wikipedia, YouTube, Zoom, etc.).
A recurring weekly 'Tiangou Secure Gateway / Server IP and Location of Overseas APP' report series tracks per-app server-IP geolocation for Instagram, Snapchat, Telegram, and Likee traffic, with entries repeatedly geolocated to Almaty, Pavlodar, and Nur-Sultan, Kazakhstan across late 2023-early 2024 -- consistent with (though not conclusive proof of on its own, given ambiguity over whether the geolocated IPs are CDN edge nodes or another artifact) an operating Kazakhstan TSG deployment continuously monitoring named social/messaging platforms.
MESA_Platform's "quic" module (built and packaged as stellar-on-sapp/sapp RPMs) implements SNI/User-Agent extraction from both cleartext GQUIC (versions 23-59) and encrypted IETF QUIC RFC9000 ClientHello payloads, and supports a QUIC SNI whitelist -- i.e. the DPI pipeline decrypts/parses encrypted QUIC handshakes to recover the destination domain rather than being blocked by QUIC's encryption.
TSG23.07 added support for FQDN substring matching (vs. exact/wildcard only) for the P19 deployment, a detection-capability upgrade.
TSG has a Lua-scriptable custom-classifier engine: operators upload a Lua script defining a custom traffic "Attribute", then build custom "App" rules matching on it. A 2024-05 ticket references a script literally named cdn_tunnel_finder.lua -- an operator-authored detector targeting CDN/domain-fronting-style tunneling.
Root-caused an Ethiopia SNI-block-failure incident to the detection mechanism itself: APP_SKETCH's FQDN-scanning module -- which exists specifically to identify Psiphon3 and Freegate via top-N SNI matching -- was CPU-expensive enough to saturate cores, triggering sapp's fail-open DDoS bypass and letting some target connections through uninspected. A signature-structure fix roughly doubled throughput (33K/s to 73K/s new connections) and disabling the fail-open bypass restored reliable blocking.