Iran has deployed a 'dual-stack' addressing pattern in which the same server receives both a globally routable public IP and an RFC1918 private address, enabling failover between global and domestic routing. DNS records document this for entities ranging from ISPs (acc4.pishgaman.net: 81.12.49.108 / 10.8.218.4) to government organizations (Vice Presidency for Management Development: 10.30.5.163 / 10.30.5.148) and private companies.

Iran's nationwide censorship redirect page is hosted at private IP 10.10.34.34, operated by Data Communication Affairs (a subdivision of TCI's Information Technology Company, AS12880). Traceroute data confirms the final public hop before this private host is 195.146.33.29, registered to Data Communication Affairs, and 24 of 27 tested Iranian networks (89%) can reach it.

§4 deployment

A scan of the full 10.0.0.0/8 block from within Iran identified 45,928 active hosts, including 20,060 on Telnet (port 23), 9,960 on HTTP (port 80), 8,029 on SSH (port 22), and 2,510 on DNS (port 53). Identified participants include TCI, government ministries (Agriculture, Education, Science), universities, and ADSL providers, establishing the private network as a purposefully designed national intranet in place since at least 2010.

§4, §5 deployment

Using open HTTP proxies distributed across 27 Iranian ASNs, the study confirmed 89% (24/27) of tested networks could reach the private filtering page (10.10.34.34) and 77% (21/27) could reach Imam Reza University's private IP. Of 15 proxies on RFC1918 addresses themselves, 13 (87%) could also reach the filtering page, confirming nationwide — not localized — private-space reachability.

§4.1 evaluation

Several Iranian domains maintain DNS A records pointing to RFC1918 private addresses that resolve only when queried against Iranian nameservers (IRNIC); the same query to Google's public DNS (8.8.8.8) returns REFUSED. Domains including realm.blizz.ir (→ 10.175.27.120), isftak.ir, and geeges.co.ir exhibit this split-DNS pattern as of September 2012.

§5.2, §6 detection

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

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

Brussee measures a systematic pattern of Chinese government websites actively blocking access from outside China (the "reverse Great Firewall"), publishing a CSV dataset of affected domains (available at zenodo.org/records/18172145). The paper frames this outbound geo-blocking as a cybersecurity-motivated practice — Chinese authorities classify foreign access to domestic government infrastructure as an attack surface — distinct from the inbound information control goal of the GFW.

2026-brussee-reverse-great-firewall §3, §5 ip-blockingasn-blackholing

Brussee develops a conceptual framework distinguishing two logics of government geo-blocking: (1) information control (blocking inbound foreign content from domestic users) and (2) data sovereignty / attack-surface reduction (blocking outbound access by foreign actors to domestic systems). Chinese government site blocking of external IPs is motivated primarily by the second logic, creating an asymmetric internet topology where CN citizens cannot reach the outside world, and outside actors cannot probe CN government infrastructure.

2026-brussee-reverse-great-firewall §2, §4 ip-blockingasn-blackholing

ShieldShare demonstrates that an Android application can route all hotspot-client traffic through a VPN tunnel without root access by using a SOCKS5/HTTP/HTTPS proxy layer between the hotspot and the VPN, with per-client traffic accounting and quota management. The system works because Android's native hotspot does not forward VPN routing tables to connected clients; ShieldShare interposes a proxy that handles this. Released as open-source.

2026-edorh-shieldshare §Abstract ip-blocking