Manually-generated FTE regexes achieve a 100% misclassification rate against all six tested DPI systems — appid, l7-filter, YAF, bro, nProbe, and the proprietary enterprise-grade DPI-X — for HTTP, SSH, and SMB target protocols. Each regex took less than 30 minutes to specify and debug against known classifiers.

FTE proxy overhead compared to socks-over-ssh: the intersection-ssh format incurred 0% average latency increase and only 16% bandwidth overhead (1,164 KB vs. 1,348 KB per Alexa Top 50 site). The worst-case auto-http format incurred 29% latency increase (5.5 s vs. 7.1 s) and 181% bandwidth overhead (3,279 KB), primarily due to ciphertext expansion and FTE/SOCKS negotiation on persistent empty TCP connections.

§5, Figure 5–6 evaluation

An FTE-tunneled Tor circuit using intersection, manual, and auto HTTP formats successfully traversed the Great Firewall of China from a VPS inside China to a server in the United States on port 80. A persistent tunnel polling a censored URL every five minutes remained active for one month until VPS account termination, with no blocking observed.

§6 deployment

Default Tor connections to a private bridge inside China were detected by the Great Firewall via active probing: an initial connection succeeded, followed by a probe from a Chinese IP address approximately 15 minutes later that performed a TLS handshake and then blacklisted the (IP, port) combination. Subsequent connection attempts resulted in a successful SYN followed by spoofed TCP RSTs terminating both the client and bridge connections.

§6 detection

Regex-based DPI is fundamentally vulnerable to format-transforming encryption: because every tested system (including the proprietary enterprise-grade DPI-X, rated for 1.5 Gbps at $8,000) classifies protocols solely by membership in a regular language, any ciphertext can be guaranteed to match any chosen regex. The paper argues this forces DPI to adopt machine learning, active probing, or non-regular semantic checks — but notes that making such checks fast, scalable, and low-false-positive at line rate for arbitrary target protocols remains an open problem.

§3, §7 detection

Stage 1 of the detection pipeline uses a lightweight heuristic: restrict analysis to IP addresses in "VPS-dense ASNs," which censors already target for resource-intensive inspection of fully-encrypted traffic. This pre-filter dramatically reduces the search space before applying the more expensive dual-role behavioral analysis. The evaluation was conducted without Stages 1 and 3 due to dataset limitations, meaning the reported 23% recall and 0.18% FPR are conservative lower bounds on the full pipeline's performance.

2026-almutairi-server §2.1, §2.2, §3.4 fully-encrypted-detectdpiml-classifier

Amnesty International's 102-page investigation identifies a multi-vendor surveillance stack deployed in Pakistan: Chinese DPI (Geedge/MESA-derived), Canadian social-media monitoring (Netsweeper), and Emirati commercial spyware (Pegasus and FinFisher). The system enables deep packet inspection, SNI-based filtering, and traffic-shape classification at national scale, including targeted interception of encrypted messaging apps and VPN traffic.

2025-amnesty-pakistan-shadows §3, §5 dpisni-blockingip-blockingtraffic-shapeml-classifier

The September 2025 leak of ~600 GB from Geedge Networks and the MESA Lab (Institute of Information Engineering, Chinese Academy of Sciences) is the largest known document disclosure from the GFW vendor ecosystem. It establishes a direct lineage: MESA Lab (founded 2012 by Fang Binxing's team, annual contracted revenue >35M RMB by 2016) spun out Geedge Networks in 2018, with MESA alumni filling key engineering roles (e.g. Zheng Chao as CTO). The leak includes ~64 GB of MESA git repositories, ~35 GB of MESA internal documents, ~15 GB of Geedge internal documents, and a ~3 GB Jira export — providing direct access to source code, work logs, and internal communications behind GFW R&D.

2025-geedge-mesa-leak §4 dpiactive-probingml-classifiersni-blockingfully-encrypted-detect

Internal Geedge documents confirm active contracts to deploy GFW-derived censorship and surveillance infrastructure in Myanmar, Pakistan, Ethiopia, Kazakhstan, and at least one additional unidentified country under the Belt and Road framework, in addition to domestic deployments in Xinjiang, Jiangsu, and Fujian. The exported product (the Tiangou Secure Gateway / TSG line) is not a stripped-down export variant — leaked TSG documentation shows DPI, active-probing, ML classifiers, and granular per-region traffic control rules that mirror the domestic GFW capability set.

2025-geedge-mesa-leak §5, §6 dpiactive-probingml-classifiersni-blockingdns-poisoningfully-encrypted-detecttraffic-shape

InterSecLab frames the Geedge/TSG export program as the commoditization of national firewall capability: rather than each censor state independently developing detection infrastructure, they contract Geedge for a turnkey system incorporating the cumulative R&D of MESA Lab (>10 years, National Science and Technology Progress Award winners). This structural shift means the marginal cost for an autocratic government to acquire GFW-grade censorship is now a procurement decision, not a multi-year engineering program. The report identifies that Geedge's relationship with the MESA Lab gives customer states indirect access to ongoing academic R&D improvements, not just a static product.

2025-interseclab-internet-coup §2, §6–§7 (InterSecLab report) dpiactive-probingml-classifier

InterSecLab's 76-page analysis of the Geedge/MESA leak (based on nine months of indexing and translating >100,000 documents) characterizes the Tiangou Secure Gateway (TSG) product line as a commercially deployable detection stack that combines deep packet inspection, real-time mobile subscriber monitoring, active probing, ML-based traffic classifiers, and granular per-region rule sets. TSG is not a research prototype — leaked documentation includes deployment timelines and client government interactions for Kazakhstan, Ethiopia, Pakistan, Myanmar, and one unnamed country, with censorship rules explicitly tailored to each region.

2025-interseclab-internet-coup §3–§5 (InterSecLab report) dpiactive-probingml-classifiersni-blockingip-blockingtraffic-shapefully-encrypted-detect