Chinese control Internet by sophisticated means

The Associated Press :: IHT: "The Chinese government has become increasingly sophisticated at controlling the Internet, taking a multilayered approach that contributes to precision in blocking political dissent, according to a report released Thursday.

The precision means that China's filters can block just specific references to Tibetan independence without blocking all references to Tibet. Likewise, the government is effective at limiting discussion about Falun Gong, the Dalai Lama, Tiananmen Square and other topics deemed sensitive, the study from the OpenNet Initiative found.

Saudi Arabia, for example, largely controls the Internet by having all traffic flow through a central agency, where it can be monitored. Visitors trying to view a banned site get a message saying it has been blocked, Palfrey said.

"China is much more subtle than that," Palfrey said. "You don't know what you don't know. It's more effective than if you see it but know you can't access it."

With filters at multiple points, including some search engines, content is simply removed rather than replaced with a notice, he said.

Google has acknowledged that its Chinese-language news service - introduced on a test basis last autumn - leaves out results from government-banned sites, though the company says that is done so users will not end up clicking on links that lead nowhere because of the Chinese filters.

China, which has the world's second-largest population of Internet users behind the United States, promotes Internet use for business and education, while trying to curb access to political dissent, pornography and other topics the Communist government deems sensitive. Many users do find ways around the controls - for instance, using "proxy" servers that mask a site's true origin.

It is through similar proxy servers and long-distance calls that researchers outside China managed to test what users inside China see. The researchers also employed volunteers inside the country to conduct more extensive testing.

The researchers deployed software and physical equipment called packet sniffers to monitor the flow of traffic and try to gauge where content gets dropped.

Financed by George Soros's Open Society Institute, the OpenNet Initiative is a collaboration of researchers at Harvard, the University of Cambridge and the University of Toronto working on issues of Internet censorship and surveillance.

Their testing determined, in part, that filtering tends to be triggered by the appearance of certain keywords, rather than a visit to a specific domain name or numeric Internet address."