University of Toronto researchers: Great Firewall blocks 311,000 domains

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Researchers at CitizenLab, a division of the University of Toronto, have developed a large-scale platform, GFWatch, that helps map the censorship of China’s Great Firewall. It shows that the Great Firewall blocks about 311,000 domains.

To find out exactly how the Chinese firewall works, researchers at the University of Toronto have developed a system that can determine which domain names are allowed in China and which are not, based on domain name system filtering. Using reverse engineering, they were then able to draw up a blacklist containing approximately 311,000 domain names that are being blocked.

Of these, about 41,000 domain names would be wrongly withheld from internet users surfing in China. Some of those domain names also contain a letter or word combination that occurs in blocked domain names, according to the researchers. This is allegedly blocking them incorrectly. They give as an example, which contains “” but that site has no affiliation with the tor network.

Most blocked domain names were divided into ten categories. This shows that domain names from the categories business world, porn industry and information technology were stopped most often. About 40 percent were subdivided into the ‘newly observed domain’ category, which indicates that these are relatively new domain names.

The researchers suspect that the filtering is partly automatic and partly manual. They came to that conclusion after tracking some domain names mentioning the coronavirus and found that, in some cases, they were blocked relatively late by the firewall compared to other blocked domain names.

Information on websites that the Chinese government considers sensitive may also be a reason to be blocked in China, according to the researchers. The investigation reports that some US websites were blocked after posting content about the Uyghur community in China. A Cannes Film Festival website was then blocked because the festival was showing a documentary about the protests in Hong Kong. The researchers keep track of their real-time findings on a separate dashboard page.

Dashboard Cutout GF Watch

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