Flash proxies provide mean throughput of 79.7 KB/s when uninterrupted — comparable to direct Tor (69.5 KB/s) — but throughput drops to 56.6 KB/s (20–40% lower) when proxies alternate on 8-second duty cycles, with most variance attributable to Tor circuit reconstruction overhead rather than transport switching.

Flash proxies successfully relayed Tor traffic from within China in December 2011, but the test relied on a simple HTTP-based rendezvous blockable by IP address; the authors identify rendezvous — getting just a few bytes (the client's IP address) out of the censored region — as the bottleneck that determines whether the entire proxy system remains operational.

§4.4, §6 deployment

Because browser-based proxies can only initiate outbound connections, flash proxies connect to censored clients rather than the reverse, requiring the facilitator to maintain a registry of client IP addresses; a censor can impersonate a legitimate flash proxy to query the facilitator and enumerate the IP addresses of circumvention users.

§5.1 detection

Applying Little's law to measured traffic parameters (mean inter-arrival time 1/λ = 1407.6 s, mean visit duration µ = 285.8 s), 100 volunteer web pages each embedding the flash proxy badge can support approximately 203 simultaneous censored clients; capacity scales linearly, so 1,000 such pages support ~2,030 clients.

§4.3 evaluation

Flash proxy tunnels carry inherent network-level fingerprints that survive application-layer obfuscation: WebSocket connections begin with a plaintext HTTP upgrade handshake followed by structured binary framing, and Flash socket connections open with a crossdomain XML policy request — both are distinguishable from ordinary TCP by a DPI middlebox.

§5.1 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

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