Of 44,797 CDN-served domains on the April 2019 Roskomnadzor blocklist, 99.6% (44,615) were hosted on Cloudflare—attributable to Cloudflare's free tier with minimal vetting enabling rapid mirror-domain creation by blocked operators; the blocklist also contained 1,769 responsive circumvention-related domains, confirming that circumvention infrastructure is an active and documented blocklist target.

Seven years of Roskomnadzor blocklist history (Nov 2012–April 2019) show the list grew to 132,798 unique domains and 324,695 unique IPs, with a dramatic spike in 2018 when Russia blocked Telegram by adding subnets covering approximately 16 million IP addresses—producing major collateral damage to co-hosted Google and Amazon services and illustrating that subnet-level blocking is the blunt instrument of last resort for CDN-hosted targets.

§VI-A, §II-B evaluation

Data center VPSes predominantly experienced TCP connection timeouts and resets—with the highest-blocking VPS censoring 96.8% of tested domains—while residential ISPs were substantially more likely to inject explicit blockpages citing Roskomnadzor's registry, confirming that blocking mechanism varies significantly by network tier even when blocking rates are similar.

§VI-B evaluation

Despite Russia's decentralized ISP ecosystem, 9 of 14 residential probes observed more than 90% of 98,098 tested blocklist domains blocked, and all 14 probes observed at least 49% blocked—demonstrating that coordinated nationwide censorship without centralized choke-points is achievable through legal mandates and commodity equipment alone.

§VI-B evaluation

Quack (which probes censorship on port 7/echo servers) detected substantially less blocking than Satellite (DNS-based): approximately 50% of Quack vantage points observed no blocking and ~90% observed only minor blocking, whereas Satellite observed major interference at most vantage points; the authors attribute this gap to Russian ISPs applying filtering predominantly on ports 80 and 443, leaving non-standard ports largely unfiltered.

§VI-B-3 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

Chinese users treat full proxy/VPN (Shadowsocks, V2Ray/Clash, commercial VPNs) as the '终极大杀器' (ultimate solution) for bypassing GitHub DNS poisoning, implying that lighter-weight DNS-only fixes fail in some network environments where the censor adds firewall-layer blocking beyond DNS.

2026-anon-6-github-dns §3 使用代理或 VPN dns-poisoningip-blocking

Rule-based proxy tools (Clash, Shadowsocks, V2Ray) are documented as the most reliable solution for accessing GitHub from China, with split-tunneling rules routing only GitHub traffic through the proxy while keeping domestic traffic on the direct path. Git command-line tools require explicit proxy configuration (git config --global http.proxy http://127.0.0.1:7890) to route clone/push operations, as they do not inherit system proxy settings automatically.

2026-anon-github-2026-6-dns §方法二 dns-poisoningip-blocking

The GFW blocks GitHub via DNS poisoning across at least four domains — github.com, assets-cdn.github.com, github.global.ssl.fastly.net, and raw.githubusercontent.com — causing connection timeouts and page-load failures for mainland China users. The block is persistent as of February 2026, affecting both browser access and command-line git operations.

2026-anon-github-2026-6-dns Introduction / §方法一 dns-poisoningip-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

Article 19 documents that Iran combines technical filtering with formal coercion of major foreign platforms (including Telegram, Instagram, and WhatsApp) to comply with content removal orders under threat of full blocking. The report notes that Iran's 2022 Women Life Freedom protests accelerated platform blocking when foreign operators refused compliance, demonstrating that the censorship system operates in two modes: coerce-and-allow for compliant platforms, block for non-compliant ones. Domain fronting via these platforms is therefore subject to sudden revocation if political conditions change.

2026-article19-tightening-the-net §6 ip-blockingdns-poisoningthrottling