IP-level access control was the most complete and effective sanctions enforcement mechanism—applied at or near the content destination—but was also the least commonly deployed approach. The paper attributes its rarity to the over-blocking risk when multiple services share a single IP address; one observed instance involved DDoS-mitigation providers performing IP-based enforcement that did not appear in DNS measurements.

Alternative DNS resolvers trivially circumvent EU sanctions enforcement: third-party providers such as Google Public DNS and Cloudflare DNS implement no sanctions filtering regardless of user location, meaning any user who can switch their resolver can bypass most enforced blocks. The paper concludes that 'as long as a user can utilize an alternative DNS resolver, they would be able to bypass most sanctions enforcement.'

§5.4 evaluation

DNS-based blocking was the dominant EU sanctions enforcement mechanism: 87% of the 125 OONI vantage points implementing blocks chose DNS, and RIPE Atlas measurements found 50% of blocking ISPs return DNS error responses. Coverage dropped with each new sanctions package—45% of vantage points blocked first-round domains versus only 17% for fourth-round additions.

§4.1, §4.2 evaluation

EU sanctions enforcement was deeply non-uniform across member states and over time: 77% of blocking autonomous systems enacted enforcement within 3 months of the initial sanctions, but adoption timelines, block-list coverage, and over/under-compliance patterns varied substantially by country and ISP. Austria blocked certain domains months after Germany despite advance specification; domains removed from the German list were eventually de-blocked with significant lag; the newly registered sputnikglobe.com was not widely blocked as of the study's writing.

§4.2, Figure 1 deployment

Mirror domains registered by sanctioned Russian outlets (e.g., rtde.site, rtde.xyz, rtde.live, rtde.tech) remained almost universally accessible across EU member states; Table 2 shows near-100% uncensored DNS responses for mirror domains in the vast majority of countries. The EU had no effective mechanism to police domain mirroring in real time, leaving it an unmitigated circumvention strategy throughout the study period.

§5.2, Table 2 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