During a major censorship event in April 2019, new censor techniques blocked many Psiphon transports while TapDance remained accessible, causing a 4× increase in the fraction of TapDance-enabled clients' traffic and daily users peaking above 25,000—with no measurable degradation in connection success rate or per-session throughput under the increased load.

Total hardware cost for four detector stations plus a central proxy was approximately $30,000 USD, with estimated annual operating costs of ~$13,000 for co-location and ~$24,000 for a 2 Gbps upstream connection, plus ~40% FTE of an ISP network engineer—costs that are structurally higher than endpoint-based circumvention due to mandatory network-operator co-location requirements.

§5.2 deployment

Over 115 days of operation with 1,500–2,000 active decoys, the busiest decoy site averaged only 13.24 concurrent connections and 12.32 MB of traffic per day; only 2 of roughly 3,000 candidate decoy sites opted out via robots.txt over 18 months, and none reported operational problems, confirming that decoy websites are not meaningfully burdened at this deployment scale.

§4.3, Table 1 evaluation

The first production Refraction Networking deployment used four TapDance stations at Merit Network observing 140 Gbps aggregate capacity and served up to 33,000 unique users per month across 559,000 Psiphon installations, proxying up to 500 Mbps of circumvention traffic during the first year of continuous operation.

§1, §3, §4 deployment

Approximately 50% of TapDance client connection attempts failed to pass through any station due to routing variability at the ISP, producing an average of about one failed decoy per successful connection and time-to-first-byte exceeding five seconds in typical cases, even though median session RTT remained under one second.

§4.4, §5.4 evaluation

The June 2025 Iran shutdown—carried out during the Iran-Israel war beginning ~June 19—did not use BGP route withdrawals as in 2019. Instead, authorities applied service-level restrictions at the national border: DNS poisoning of foreign destinations, protocol whitelisting permitting only pre-approved domestic services, and DPI to block circumvention-tool traffic. Iran's international traffic fell roughly 90% while the country's BGP routes remained advertised, making the shutdown invisible to BGP-based monitoring systems. OONI measurement volume, which totalled 121,333 in June 2025, collapsed to under 200 submissions on June 19-20.

2025-iran-shutdown-measurement Executive Summary / §2 dpidns-poisoningport-blockingip-blocking

Article 19 documents that Iran's National Information Network (NIN / SHOMA) was designed with explicit reference to China's Great Firewall as a model, with institutional mirroring: Iran's Supreme Council of Cyberspace parallels China's Cyberspace Administration of China, and both governments share a "cyber sovereignty" doctrine used to justify domestic content controls and cross-border technology transfer. The report frames Iran's filtering infrastructure as deliberately architected to replicate GFW capabilities, not as an independently developed system.

2026-article19-tightening-the-net §2, §3 dpisni-blockingdns-poisoningip-blockingbgp-hijackthrottling

The GNL reveals that Geedge actively maintains dedicated VPN-infrastructure tracking datasets. The China-specific component includes 7,016 domains in a "vpn-finder-plugins" repository (mesalab_git/intelligence-learning-engine), 4,810 NordVPN server domains, and a Pakistan-specific file listing 68 Psiphon CDN domains (geedge_docs/TSGEN/.../Psiphon-CDN_20240430.json) dated April 2024. A Myanmar deployment file (M22-VPN List.html, 27 domains) further confirms country-specific VPN blocklists are operationally maintained. The "Appsketch" program reverse-engineers VPN apps to extract domains and IP addresses for blocking.

2026-sheffey-geedge §4.2, Table 3 dpisni-blockingip-blocking

Iran's censorship of refraction-networking proxies (Conjure via Psiphon) is not monolithic: different ISPs independently deploy different techniques and timelines. Over 800 million logged Conjure connections from July 2023–February 2025 across 10+ Iranian ASes show TCI (AS58224, ~33% of traffic) uses packet injection, while MCCI/Hamrah-e Avval (AS197207, ~22%) applies IP-based blocking, and some ASes (Parsonline AS16322, Shatel AS31549) show no proxy blocking at all.

2025-alaraj-iran-refraction §4 rst-injectionip-blockingpacket-injectiondpi

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

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