The Great Firewall of China (GFW) is a multi-layered censorship system operated by the Cyberspace Administration of China (CAC). It blocks access to thousands of websites including Google, Facebook, Twitter, YouTube, Wikipedia, and most Western news outlets. The GFW employs deep packet inspection to identify and block VPN protocols, Tor traffic, and other circumvention tools in real time.
Since 2012, the GFW has specifically targeted Tor by blocking all known public relay IP addresses and using active probing to identify and block Tor bridges. The system can detect the TLS fingerprint of Tor connections and terminate them mid-handshake. During politically sensitive periods - such as the anniversary of Tiananmen Square or the National People's Congress - censorship is intensified, and even previously working circumvention methods may fail temporarily.
Despite these measures, Tor usage in China persists. The Tor Project continually develops new pluggable transports specifically designed to evade the GFW's detection capabilities. With the right configuration, users in China can still establish Tor circuits and access the uncensored internet.