Update March 22: A reader reported back via email that only some of the PPTP and L2TP protocols have been blocked and interrupted in China and he has not encountered any problem connecting with PPTP and L2TP problem in Beijing. Some users from Guangzhou pointed out that the blocking / disruption mainly affect mobile phone but not computer. Bestvpnservice.com also has an update (March 21) situation.
In order to get around the Great Fire Wall and visit blocked website such as Twitter and Facebook, many Chinese netizens subscribe to VPN services.
However, it has been confirmed that three of the most popular VPN providers in China: Witopia, 12VPN and StrongVPN have been blocked or disrupted since March 16 2011 as a result of the blocking of PPTP and L2TP VPN Protocols.
VPN services has become more and more popular for middle class and foreign expats in China to get access to overseas website. Rodders Gillam from Street articles explains the advantage of using VPN in China:
A vpn is designed to code, package, and send your information to another location before being opened, decoded, and sent back to you. In this way businesses are able to exchange private information without the risk of being hacked or spied on. In the same way, people living inside The Great Firewall are able to code, package, and send out their private information without the prying eyes of Big Brother asking what they're doing. A vpn in China gives individuals the privacy and freedom internet users in The West don't have to think about on a daily basis. In China, where social bookmarking (the Western kind) is almost totally inaccessible, getting on Facebook and updating your status is a luxury.
According to Bestvpnservice.com's news on March 16, 2011, PPTP (Point-to-point Tunneling Protocol) and L2TP (Layer 2 Tunneling Protocol) VPN Protocols have been blocked. The two protocols are mainly used for mobile devices for connecting to a private network. The new censorship measure is to prevent social network mobilization, like the recent Chinese Jasmine Revolution call, which is organized by overseas Chinese community and delivered to their mainland counterpart through blocked social media websites such as Twitter and Facebook.
There are ways for netizens to get connected to the blocked VPN still. StrongVPN has already fixed the problem for their Chinese clients. However,12vpn urged their Chinese clients not to discuss solutions and alternatives in public:
@12vpn: Please make sure to discuss any solutions/alternatives in private, not on Twitter or other public forums. The GFW *does* read.
Some websites, such as Bestvpnservice.com advises Chinese VPN users to shift to SSTP (Secure Socket Tunneling Protocol)/SSL(Secure Sockets Layer) and SSL/OpenVPN based services to access overseas websites.