China has tightened the screws on its infamous web-filtering system, according to virtual private network providers.
The Great Firewall of China has been enhanced to "learn, discover and block" encrypted VPN protocols. Machine learning algorithms have been applied to carry out encrypted traffic analysis, something advocated by Fan Bingxing, the founding father of China's web filtering system.
China Unicom drops connections where a VPN is detected, The Guardian reports. Astrill, an application that provides VPN services to users inside and outside China, warned consumers in an email that the "Great Firewall" system is blocking at least four common VPN protocols.
The latest developments provide a technical basis that supports earlier reports that China was planning a clamp-down on VPN technology.
The development marks the latest phase in the cat and mouse game between privacy protecting and surveillance technology.
VPN services establish more secure tunnels across the internet. As well as providing privacy in insecure locations, such as Wi-Fi hotspots, the technology can also be used to access otherwise blocked websites. Within China, VPNs allow locals to access services blocked by the great Firewall, which include Twitter, Facebook, and Western media outlets. ®