Rarely, the “Great Firewall” responsible for censoring the Chinese Internet, has been measured

The “Great Firewall”, the Chinese government’s gigantic Internet censorship tool, blocks more than 311,000 domains.

Among the internet censorship regimes, China is among the most famous, having developed an advanced filtering system, known as the ‘Great Firewall’, to control the flow of information online. », Introduces a team of nine researchers from four American and Canadian universities. Their study, spotted by The Record Media, aims to measure the size and effects of the gigantic firewall deployed by the Chinese government to control the browsing of its citizens.

Between April and December 2020, scientists used GFWatch, a system developed for the occasion, on a daily basis. This tool measures how the “Great Firewall” (GFW) intervenes at the level of DNS servers to prevent the Chinese from reaching certain sites. Basically, DNS servers serve as a guide in browsing the Internet. When you look for a site, for example, they are responsible for finding its IP address (a series of numbers separated by periods) so that your browser can connect to it. If the DNS is manipulated, it may point to a different page than the one requested, or never find the corresponding IP address.

For their project, the researchers connected to an average of 411 million sites per day to ensure the continuity of the blockages they observed. In all, they tested over 534 million domains. Their record? The digital Great Wall blocks ” around 311,000 domains ”, Or less than a thousandth of the total.

New domains are blocked by default

Of the 311,000 blocked domains, the researchers noticed that 41,000 of them were blocked … by mistake. The proof that such a system of censorship is not so easy to control. For example, scientists detail that the blocking of the famous forum platform has generated collateral blocks on more than a thousand unrelated sites, such as or The reason ? The filter implemented at the DNS level targets the expression “reddit” but does not exclude cases where “reddit” is included in a longer word.

The study does not stop at quantity, it also assesses the quality of blocked content. The reason for the blocking, for 40% of the domains, is that the domain name was registered recently. However, the Chinese authorities block by default all new domains, the time to categorize their content and possibly integrate them into the whitelist. The remaining 60% of blocked domains contain all kinds of content: commercial information, pornography, betting sites, media, personal blogs or even … malware hosts.

Finally, the scale of the Great Firewall seems smaller than what one might imagine: “ We have found that most of the domains blocked by GFW do not appear on the lists of the most popular sites. In figures, only 1.3% of blocked sites are among the 100,000 most popular sites on the Internet.

However, it should be borne in mind that the ” Golden Shield Project », An integral part of the Great Firewall does not stop at DNS filters. Specialized units of the Chinese police monitor speeches made online, looking for any opposition to the ruling power.

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