How The Great Firewall of China Works

The Great Firewall of China (GFW), officially known as the Golden Shield Project (金盾工程), is the system that filters, blocks and censors the flow of information online within the People’s Republic of China as sanctioned by the government to “protect” its citizens from the content it deems harmful to societal stability (or “harmony” as they call it). It’s a multi-faceted system made up of both technological and human elements which when combined together create a walled-garden version of the internet minus all the stuff the government dislikes.

Here’s a great video which explains how it works in layman’s terms:

Predictably it’s blocked in China so for folks there here’s a quick summary:

1. IP Blocking – each computer on the internet has a unique address that the government block if they find it to host content they don’t want to be seen inside China.
2. Keyword Filtering – the government control all the international internet gateways so can block specific pages based on keywords in their address (URL) and content which is matched against a blacklist.
3. Self-Censorship – all internet companies operating within China are required by law to self-censor their content or face harsh penalties and possible shutdown if they don’t.
4. Enforcement – it is estimated that approximately 30,000 Chinese “internet police” are monitoring Internet traffic and blocking content that is deemed undesirable.

With such a sophisticated system the government can block whole sites, individual pages and even specific search results on-the-fly which they can update or change based on unfolding events in the news or political climate etc. Scary stuff.

While the state prescribes broad categories of content which isn’t permissible the rules are far from clear leaving a great deal of ambiguity about what’s off-limits and without any transparency, there is no recourse for an appeal or even to get an official statement about why something may have been blocked. Companies operating within China often err on the side of caution when it comes to self-censoring their content and diligently delete anything which may bring themselves into disrepute with the government (one of the reasons why Google has exited the country).