Glossary · Circumvention

GFW (Great Firewall of China)

Also calledgreat firewallchina firewallgfw of china

Definition

The Great Firewall is China's national-level internet filter — one of the most technically sophisticated censorship systems in operation.

Explanation

In depth

The GFW combines DNS poisoning, IP blocking, TLS SNI inspection, DPI protocol fingerprinting, and active probing of suspicious connections. It blocks Google, YouTube, Instagram, X, Facebook, WhatsApp, ChatGPT, and thousands of other Western services. Consumer VPN protocols get identified and dropped within days of a new provider entering the market. Obfuscated protocols (Shadowsocks, V2Ray, Trojan) survive longer by making circumvention traffic look like ordinary HTTPS. Web proxies over HTTPS to mainstream domains often slip through because blocking all HTTPS to those domains would break too much of the normal web. Users are responsible for compliance with local Chinese law regarding internet-access tools.

See alsoUnblock sites from China

Related terms

DPI (Deep Packet Inspection)Deep packet inspection reads not just packet headers but payload contents to identify and filter specific protocols, applications, or destinations.TLS SNITLS Server Name Indication (SNI) is a field in the TLS handshake that names the destination hostname — visible to any network observer even when the connection itself is encrypted.SNI inspectionSNI inspection is a firewall technique that reads the destination hostname from the TLS handshake and blocks connections to specific domains.RoskomnadzorRoskomnadzor is Russia's federal executive agency responsible for media and telecom oversight — including the national blocklist enforced by Russian ISPs.

Put the concept to work

Try AnyProxy free — no install, no signup, six regions.

Open a blocked page