Jio, India's largest ISP serving 49.7% of internet users, employs SNI inspection to block 2,951 out of 3,340 websites it censors — the first documented use of SNI-based blocking in India. No other of the six tested ISPs uses this technique.

A proposed HTTP censorship detection algorithm combining status-code comparison, response-length Z-score, HTML TF-vector cosine similarity, and redirect-hostname matching achieves F1 scores of 0.83 (censored) and 0.77 (uncensored), outperforming OONI (0.80 / 0.70), length-difference methods (0.70 / 0.66), and HTML-similarity methods (0.52 / 0.34) on a manually annotated set of 3,000 responses across six Indian ISPs.

§4.3, Table 1 evaluation

All detected HTTP censorship events in BSNL and MTNL are attributable to infrastructure shared with or operated by Airtel and ACT, demonstrating that upstream ISP filtering creates collateral censorship visible to downstream networks. Isolated cross-ISP leakage was also observed: Vodafone's censorship notice appeared in 2 Jio tests, and Airtel's appeared in 2 Vodafone tests.

§5.1.3 evaluation

Indian ISPs use heterogeneous and overlapping censorship mechanisms with no single technique common across all providers: DNS tampering (ACT, Airtel, BSNL, MTNL), HTTP header filtering (all six ISPs), and SNI inspection (Jio only). Individual ISPs such as ACT simultaneously apply DNS-only blocking to 233 sites, HTTP-only to 1,873 sites, and both to 1,615 sites.

§5.1, Table 2 evaluation

Across six ISPs covering 98.82% of Indian internet subscribers, only 1,115 out of 4,033 tested blocked websites (27.64%) are blocked by all six ISPs simultaneously. ACT blocks 3,721 websites while Airtel blocks only 1,892, and 215 websites are blocked by exactly one ISP with no apparent legal basis.

§5.2, Table 3 evaluation

The paper identifies a fundamental architectural vulnerability in single-IP circumvention designs: a relay must generate new observable flows (via DNS or TLS SNI) to reach end services after receiving client connections, creating a detectable server-and-client behavioral contrast. A relay accessing user-facing domains (news, social media) scores high on a Relay Suspicion Score (w=0.9) versus infrastructure domains (w=0.1). The paper argues this host-level signal is censorship-invariant and cannot be concealed by link obfuscation.

2026-almutairi-server §2.4, §4 traffic-shapedpisni-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 report maps specific Belt and Road Initiative Digital Silk Road projects through which Chinese technology vendors have transferred censorship and surveillance infrastructure to Iran, including fiber backbone investments, data-center co-location agreements, and equipment supply chains. Specific vendors named include Huawei and ZTE as network infrastructure providers, with the report noting that equipment exports include filtering-capable hardware that Iran's ISPs have deployed at network choke points.

2026-article19-tightening-the-net §4, §5 dpisni-blockingthrottling

QUICstep successfully circumvents the GFW's QUIC SNI censorship (active since April 2024) in live testing. Using an Alibaba VM in mainland China as client and an AWS instance in North Virginia as server, a native QUIC client was blocked after several fetches of youtube.com SNI, while QUICstep consistently succeeded across 50 consecutive fetches. 7 tiktokcdn.com subdomains that were QUIC-SNI blocked were also reliably accessible via QUICstep. The approach routes only QUIC long-header (handshake) packets through a WireGuard tunnel; all subsequent short-header (data) packets travel the native path.

2026-lee-quicstep §4.3.2, §3.2.3 http3-quic-blocksni-blockingdpi

The largest single source of censored domains in the GNL is MESA lab's SNI monitoring dataset (E21-SNI-Top200w.txt) containing 57,362 censored domains, and E21-SNI-Top120W-20221020.txt with 36,467 domains—totaling over 93K domains from network tap data alone for a single country (E21 = Ethiopia per InterSecLab attribution). A separate Xinjiang dataset (XJ-CUCC-SNI-Top200w.txt) contains 13,604 domains. These datasets "do not seem to come from popular domain lists, and instead appear to be gathered from network taps," confirming that Geedge builds censorship target lists directly from passive traffic observation.

2026-sheffey-geedge §4.2, Table 3 dpisni-blockingmeasurement-platform

Of 6,915,266 domains extracted from the 572 GiB Geedge Networks Leak (GNL), 298,955 censored domains (93.7% of all GNL-censored domains) appear in neither Tranco top-1M nor CitizenLab test lists. Measurements across China (Guangzhou/Nanjing), Myanmar, Pakistan, and Algeria confirmed censorship via DNS injection and SNI-based TLS connection termination. The GNL covers 25–62% of Tranco-censored domains across countries, showing substantial but incomplete overlap. This vendor-side ground truth reveals a censorship surface roughly two orders of magnitude larger than curated academic test lists.

2026-sheffey-geedge §4.1, Table 2 dpisni-blockingdns-poisoningmeasurement-platform