Wearing Down the Great Firewall of China One Plug-In at a Time


Janani Ravikumar
Staff Writer

With the help of a simple browser plug-in developed by researchers at the University of Massachusetts, Amherst, it could soon be possible to access a variety of blocked news sites and even social media platforms from inside China, according to Technology Review.

China first began controlling its citizens’ internet access, screening and blocking internet content, in the mid-1990s, CNN reports. Since then, censorship has been constantly at odds with activists and developers who seek to exploit loopholes in the “Great Firewall.” Beijing’s attempts, once written off as misguided and doomed for failure, have somehow managed to thrive and grow in size and resilience. Only about one to three percent of internet users in China regularly jump the Firewall to gain full access to the internet, according to CNN.

New York Times reports that 16 of the world’s 30 most visited websites are inaccessible in China, thanks to the Firewall. This includes Facebook and Google, though alternative sites like Yahoo and Bing are available. In some cases, such as Google’s, web companies are unwilling to cooperate with the Chinese government’s surveillance program, while other web services are blocked simply because they are foreign. Many blocked websites have Chinese counterparts — for example, the Chinese equivalent of Google is Baidu, and people use Weibo when they can’t access Twitter — but these sites are still heavily filtered, censored and engineered to prevent any sort of conversation pertaining to politics or current events.

The new browser plug-in, CacheBrowser, developed by UMass Amherst assistant professor Amir Houmansadr and former student John Holowczack, provides a solution that doesn’t slow browsing quite as much as previous attempts to circumvent the Firewall.

China’s censorship system relies on blocking computers from accessing certain web and IP addresses, which pinpoint specific servers of blacklisted sites whose content is typically downloaded directly by computers from the servers of a content delivery network. CacheBrowser exploits a certain mechanism that allows computers to sidestep censors and access the pages it wants directly, simply by making companies’ pages load faster.

“Contrary to proxy-based circumvention systems like Tor and Psiphon, CacheBrowser takes a new circumvention approach, which we call publisher-centric,” Houmansadr and Holowczack wrote in their report on the project. “In this approach, end-users make no use of third-party proxies to retrieve censored Internet content, but instead obtain the censored content directly from the content publishers.”

For sites that use encryption, CacheBrowser cannot be easily shut down without censors blocking access to thousands of popular, uncensored websites in the process. Censors typically leave content delivery networks alone, as most servers don’t want to block them.
“They’ll have to block thousands or millions of other webpages,” Houmansadr said. “This advances the arms race in censorship resistance.”

Charlie Smith, who works with the nonprofit GreatFire.org under a pseudonym, says that CacheBrowser’s use of content delivery networks could prove to be extremely effective in resisting China’s recently increasing control of the internet.

“Many internet users in China are scrambling to find new ways to get around censorship,” Smith said. “The more working circumvention solutions there are, the better it is for everybody.”