Jens Asbjørn Bøgen
The Great Firewall of China have disconnected it’s citizens from the global internet before, but it has usually been on purpose.
The Great Firewall of China have disconnected it’s citizens from the global internet before, but it has usually been on purpose.
What is happening?
In a rare and disruptive event, China’s internet censorship system—known as the “Great Firewall”—experienced a malfunction that severed much of the country’s access to the global internet.
The incident occurred in the early hours of August 20, 2025, and affected millions of users across the nation.
Internet outage traced to port 443
According to the activist group Great Firewall Report, the outage specifically targeted TCP port 443—the standard port for secure web connections.
This port is essential for accessing most websites and services, particularly those using HTTPS encryption.
Forced disconnections
Wednesday between 12:34 a.m. and 1:48 a.m. Beijing time, China’s censorship system began injecting fake TCP RST+ACK packets into the network.
This technique forces connections to close abruptly, effectively blocking all web traffic that relies on port 443.
Why port 443 matters so much
Port 443 is the lifeline for secure internet browsing. It’s used by countless services and platforms to transmit encrypted data.
When it’s blocked, websites, apps, and even essential business operations can grind to a halt—especially those dependent on international servers.
Major brands like Apple and Tesla hit
Because services like Apple’s iCloud and Tesla’s connected car features use port 443, the block disrupted their operations in China.
Any platform requiring a connection to servers outside the country was either severely limited or rendered completely unusable during the outage.
No clear political trigger this time
Beijing often tightens internet controls around politically sensitive dates, like the anniversary of the Tiananmen Square massacre.
But according to the tech-media, The Register, analysts have found no obvious reason for this sudden escalation in censorship—leaving the cause unclear.
A mysterious device behind the glitch?
The Great Firewall Report noted that the device responsible for the block didn’t match known equipment typically used in China’s censorship system.
This could mean a new tool was being tested—or that an existing device was misconfigured, possibly due to human error.
Was it just a test gone wrong?
Speculation is mounting that Chinese authorities were experimenting with new methods of internet control and that the port 443 block may have been an unintentional side effect.
Alternatively, it may have been a trial of a stricter control mechanism.
Pakistan’s internet drop raises eyebrows
Interestingly, a major internet disruption was also reported in Pakistan just hours before the Chinese glitch.
Given that Pakistan has reportedly adopted similar censorship tools, some experts wonder whether the two incidents are connected.
