The Great Firewall of China

When you use the Internet, it often feels placeless and virtual, but it’s not. It runs on real wires that cut through real geographical boundaries. There are three main fiber-optic pipelines in China, giant underground cables that provide Internet access for the public and connect China to the rest of the Internet outside its borders. The Chinese government requires the private-sector companies that run these fiber-optic networks to specially configure “router” switches at the edge of the network, where signals cross into foreign countries. These routers — some of which are made by Cisco Systems, an American firm — serve as China’s new censors.

If you log onto a computer in downtown Beijing and try to access a Web site hosted on a server in Chicago, your Internet browser sends out a request for that specific Web page. The request travels over one of the Chinese pipelines until it hits the routers at the border, where it is then examined. If the request is for a site that is on the government’s blacklist — and there are lots of them — it won’t get through. If the site isn’t blocked wholesale, the routers then examine the words in the requested page’s Internet address for blacklisted terms. If the address contains a word like “falun” or even a coded term like “198964” (which Chinese dissidents use to signify June 4, 1989, the date of the Tiananmen Square massacre), the router will block the signal. Back in the Internet cafe, your browser will display an error message. The filters can be surprisingly sophisticated, allowing certain pages from a site to slip through while blocking others. While I sat at one Internet cafe in Beijing, the government’s filters allowed me to surf the entertainment and sports pages of the BBC but not its news section.