China’s Great Firewall (GFW) unexpectedly blocked all traffic to a common HTTPS port for over an hour, severing connections to the outside world without any apparent reason. GFW Report, a site that monitors China’s internet censorship systems, reported that the GFW injected forged TCP RST+ACK packets to disrupt all connections on TCP port 443 for approximately 74 minutes before resuming normal operations.
TCP port 443 is typically used for HTTPS, but the GFW’s behavior differs from previous efforts to censor encrypted communications. Unlike in August 2020, when the GFW targeted specific protocols and ports, this incident specifically targeted port 443 without disrupting other common ports like 22, 80, or 8443.
The cause of the incident remains unclear, with GFW Report suggesting it might have been caused by a new device or an existing one operating in an unusual state. The investigation was hindered due to the short duration of the incident.
The Great Firewall’s unique nature stems from China’s attempts to balance open internet access with restricted information flow. Unlike other authoritarian regimes that can simply cut off internet access, China relies on its GFW as a compromise between these two extremes.
Source: https://www.tomshardware.com/tech-industry/cyber-security/chinas-great-firewall-blocked-all-traffic-to-a-common-https-port-for-over-an-hour-with-no-hint-as-to-its-intention