Tor Bridges for Iran

Iran's filtering system operates at the ISP and national gateway level. Deep packet inspection targets Tor's TLS handshake signature and the specific byte patterns of Tor traffic. Standard Tor (without bridges) is blocked by most Iranian ISPs. The filtering is sophisticated: it has historically blocked obfs4 during periods of heightened censorship (political events, protests) and recovered obfs4 bypass capability between those periods. Snowflake and WebTunnel have shown more consistent bypass capability in Iran because they masquerade as standard HTTPS WebRTC and HTTPS websocket traffic respectively - signatures harder to block without breaking legitimate web services. The situation changes rapidly: during the 2022 protests, virtually all VPNs and Tor configurations were temporarily blocked. The period after restabilizes. Users should have multiple configured options (different bridge types, different providers) to fall back to when one is blocked.

Snowflake is currently one of the most reliable pluggable transports in Iran. It uses WebRTC (the same technology used by video conferencing apps like Google Meet) as its transport. Blocking Snowflake would break many legitimate applications. In Tor Browser: open Tor Browser, click Configure Connection at the startup screen, enable Use a bridge, select Built-in bridges, choose Snowflake. Tor Browser configures Snowflake automatically. For Tor from command line: install the snowflake-client binary (available from the Tor Project), configure it in torrc with ClientTransportPlugin snowflake exec /usr/bin/snowflake-client and Bridge snowflake 192.0.2.3:80 (the address is a placeholder - Snowflake finds its actual broker dynamically). Snowflake's proxy volunteers are run by people worldwide - when you use Snowflake, you connect to a volunteer's browser tab or standalone proxy, which relays your connection to the Tor network. This decentralized architecture makes blocking difficult.

Standard obfs4 bridges from the default Tor Project pool are often known to Iran's filtering system. Fresh, private obfs4 bridges have better success rates. Sources for fresh bridges: (1) bridges.torproject.org: request up to 3 bridges at a time (accessible via Tor itself - use a Snowflake connection first if Tor is blocked). (2) Email request: email bridges@torproject.org from a Gmail or Riseup account - the email response contains bridge addresses. (3) Self-hosted bridge: running your own obfs4 bridge on a server in Iceland or Romania provides a private bridge that filtering systems have not yet catalogued. Private bridges have the highest bypass rates because they are not in any public database. A Romania VPS Mini at $19.99/mo is sufficient for a private obfs4 bridge. Configuration: share the bridge address (from /var/lib/tor/pt_state/obfs4_bridgeline.txt on your bridge server) with trusted contacts in Iran via end-to-end encrypted messaging.

When Tor bridges fail entirely, Psiphon and Lantern serve as backup circumvention tools. Psiphon: a centralized VPN-like tool with a large infrastructure and frequent IP rotation. It uses a variety of protocols (SSH, VPN, obfuscated HTTPS) and automatically selects the best working option. Psiphon is available for Windows, Android, and iOS and is widely used in Iran. Lantern: a P2P circumvention network where users in censored countries connect through volunteer peers in uncensored countries. Lantern uses a proprietary protocol with domain fronting and rotates infrastructure rapidly. Both Psiphon and Lantern are more centralized than Tor (the organizations operating them know users' traffic patterns) but are often more reliable during acute censorship crackdowns. The strategy for Iranian users: configure Tor with Snowflake for daily use, have Psiphon installed as backup for when Snowflake is temporarily disrupted, and configure obfs4 with fresh private bridges as a secondary Tor option.

Censorship technology and bypass methods are in constant evolution. Stay informed: (1) OONI (Open Observatory of Network Interference) publishes measurement data on what is blocked in Iran. The OONI Explorer shows current blocking status for Tor, VPNs, and other services. (2) Tor Project's blog and mailing lists announce new bridge types and workarounds when major blocking events occur. (3) Community knowledge: Persian-language tech communities on Telegram and Signal groups share working configurations rapidly after censorship events. (4) NetBlocks.org monitors global internet outages and censorship events and reports on Iranian blocking in real-time. Keep Tor Browser updated - new versions often include improved pluggable transport versions or new bridge types specifically addressing recent blocking measures. Tor Project prioritizes updates when major censorship events affect large user populations.