China’s Great Firewall Case studies in censorship

A surprisingly large number of countries exercise at least some control over what content their citizens can and cannot access on the Internet. In many cases, this means very selective blocking of information considered to be harmful, but a handful of countries have developed much more powerful tools to regulate Internet access for political and social reasons. I’m planning to write a few articles about Internet censorship, starting with a look at the country that didn’t just build the great wall to keep outsiders out – it also build the Great Firewall. We’ll start in China!

Over the past years, China’s communist government has seen the benefits of the Internet to support economic growth and innovation. And the same time, they’ve been very worried the Internet could become a platform for social change, dissent and opposition. Thus, they’ve started a number of projects that allow them very strict control over what exactly is allowed – and what isn’t. These projects include the Golden Shield, the Great Firewall and the Great Cannon.

Starting with the Great Firewall, its main purpose is filtering access to foreign websites. Attached to the three national Internet exchange centres, and also some of the ISP’s, it regulates traffic between China and the rest of the world. Its capabilities include blocking specified IP-addresses or hostnames by using DNS poisoning and resetting TCP connections, or blocking traffic when it detects certain keywords in the URL or package contents. The Great Firewall is also thought to be capable of blocking VPN traffic and performing Man in the Middle attacks, using a root certificate issued by the Chinese Internet Authority. 

In addition to this, the Great Cannon provides an offensive capability. It is able to intercept incoming traffic, inject malicious code or malware and reroute the traffic to different destinations. This makes it possible to launch massive Distributed Denial of Service Attacks, such as the attack on Github in 2015.

It would be a mistake however, to consider this issue just in terms of technology. The Golden Shield project monitors China’s domestic Internet internally. It has many ways to do that, and some of its most effective tools are not hardware or software. China has its political and economical leverage at its disposal. For domestic and international Internet companies to operate in China, they have to follow the rules set by the Chinese government.  Google is perhaps the most famous example of a company that has long struggled with the question of whether they would offer a censored service in China, or rather not enter the market at all. For now, the plans are on hold as large number of Google employees protested against it.

The law is also used to control the behaviour of citizens. Individuals convicted of spreading lies or rumors online face prison sentences of up to three years. Helping track down such individuals and moderate content online is an army of “internet public opinion analysts”, consisting of an estimated 2 million(!) people employed to monitor and censor content online.

Of course, Internet users have been searching for ways around these barriers. Users finding their posts deleted by moderators have found creative ways to phrase their opinions. This has, in time, resulted in censorship of unexpected topics such as Winnie the Pooh and even the letter ‘N’.  Technological avenues exist as well. I’ll explore these in a future post.

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