- China’s web traffic was blocked to access external websites
- They do not seem to coincide political or sensitive events
- Pakistan also suffered an interruption before
China seems to have closed from the Internet world for more than an hour earlier this week, but could it have been a mistake?
The country’s “Great Firewall” interrupted all traffic in port TCP 443, used for HTTPS, for 74 minutes on August 20, 2025, but with most of the sleeping citizens during interruption (00: 34-01: 48 Beijing time), was this expected behavior?
Interestingly, only port 443 was affected, leaving other ports such as 22 (SSH), 80 (HTTP and 8443 (alternative HTTP) not affected.
China has just had a partial internet interruption
When injecting RST+ACK TCP packages forged to cut connections in port 443, the Great Firewall blocked access to most websites outside China and also interrupted the services that depend on the servers on the high seas, including Apple and Tesla.
A report explained that China’s Great Firewall is not a unique entity, but a “complex system composed of several network devices that censorship.” The device involved did not match the digital footprints of known GFW equipment, which suggests that the interruption of 74 minutes could come from a new censorship device, a badly known known division or a test of port blocking capacity.
The Great Firewall also has a history of failures, leaks and other technical errors.
Unlike previous censorship events, political events or other sensitive events were not identified during this interruption, which makes the reason more obscured.
Coincidentally, Pakistan also saw a great fall in Internet traffic hours before Chinese interruption. The two countries have similar stories of censorship on the web, and China has even been related to the exchange of censorship technology with Pakistan, which potentially attracted a link between the two events.
In more general terms, granular and more complex censorship that China chooses (compared to the total closures observed in Turkey, Sudan and Egypt) attacks an act of fine balance between restricting access to foreign information while avoiding economic damage.
With the community responding to the comments of the report with suspicions that this could have been a test, we have little more evidence than to believe that this is the case, or it was a mistake.
