by meskio and shelikhoo | December 3, 2025
From internet blackouts in Iran to Russia's evolving censorship tactics, 2025 has tested Tor's anti-censorship tools like never before. These are the moments where the work of Tor's anti-censorship team is more important than ever, to fulfill our mission of preserving connectivity between users in affected regions and the rest of the world.
In this blog post, we want to talk about what we've learned, how we've adapted, and what other internet users can do to keep Tor users connected.
Iran
In June, during the war between Iran and Israel, the censorship in Iran intensified up to a point where internet was disconnected for few days. Presumably to impede espionage-related communication while simultaneously consolidating political power.
Monitoring the censorship landscape
During this period, we were constantly monitoring the situation using our in-region vantage-point system. This vantage-point system is a network of monitoring locations inside Iran that provides more recent and accurate information about censorship than is available from public data.
One clear example is domain-fronting data. Domain-fronting is a technique that makes Tor traffic look like other popular, harder-to-block websites (like major cloud services). To determine which domain-fronting configurations perform best across the most locations, we deployed an automated testing tool that detects and reports the accessibility of the Snowflake broker and the Moat service for each domain-fronting configuration at each of our vantage points. This information is then aggregated by the log collector and subsequently used to monitor the domain-fronting configurations currently in use and to select the configurations to use in the future.
Strengthening Snowflake
Snowflake is the most used network traffic obfuscation tool in Iran. Over the past year we have been working on improving it to ensure that it remains strong and accessible to users.
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