China tightens Internet control by blocking VPN services

Several foreign-based operators of virtual private network (VPN) services said Friday that access to their services in China had been disrupted as a result of the crackdown and users are facing a harder time getting to some foreign websites.

Virtual private networks work by establishing an encrypted pipe between a computer or smartphone and a server in a foreign country. All communications are sent inside the pipe, effectively shielding Internet traffic from government filters that determine whether a site can be accessed. VPNs are used by Chinese citizens to get to external news sources and by resident foreigners and businesses for day-to-day communications.

StrongVPN, a commercial provider that operates a network of servers around the world, said users in China had recently begun experiencing connection problems to some of its sites. Comments alongside a company blog post indicate the list of sites affected is changing and sites that might work one day are failing the following day.

Another VPN provider, Golden Frog, told customers they might have more success connecting to services in Hong Kong or The Netherlands than those in the United States or Australia.

The Chinese government appears to be using two techniques to disrupt service, said Andrew Staples, a spokesman for Golden Frog. One, deep packet inspection, examines the data in Internet packets to try to determine if it's a VPN connection. The other, IP blocking, shuts off traffic destined for the Internet addresses used by VPN servers.

"This weeks attack on VPNs that affected us and other VPN providers is more sophisticated than what weve seen in the past," Sunday Yokubaitis, president of Golden Frog, said in a statement.

The problems have been caused by an upgrade to China's censorship system, reported the English-language Global Times newspaper. The state-run paper quoted unnamed Chinese analysts as urging Internet users to abide by the government's Internet censorship system "for safety."

China has over 600 million Internet users and all of them are governed by the Great Firewall -- an elaborate censorship system that proscribes certain topics from domestic websites and filters out overseas sites carrying reports the Chinese government doesn't want its citizens to read.

The list of blocked sites changes all the time but includes major news sites such as the BBC, social media sites including Twitter and Facebook, and sites such as Wordpress, Google Maps and Bing. Recently, access to Gmail was also blocked -- something that brought a lot of inconvenience to foreigners living in the country and caused many to increase their reliance on VPNs.

Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is martyn_williams@idg.com