China's government is cracking down further on the use of virtual private networks to circumnavigate its Great Firewall, as part of the ongoing game of whack-a-mole between censors and an increasingly tech-savvy population.
Charlie Smith, co-founder of the censorship in China monitoring site GreatFire.org, said there has been a significant increase in the usage of VPN services over the last year.
"This is a direct result of the authorities blocking more websites in China, causing huge inconvenience," he said. The knock-on effects of this can be seen through increased activity on blocked sites such as Twitter.
However, Smith said the authorities have recently cracked down hard on the most popular commercial VPNs.
"New upstarts might garner the same attention once they hit critical masses of users. I hope that this does not happen, but recent trends indicate that this will be the likely end result."
According to sources, the country's hugely popular online shopping platform Taobao no longer sells VPNs, with keyword searches for the services now blocked. A search on China's Baidu reveals more people are asking where to buy VPNs, although there are still plenty of sites selling them.
Adam Fisk, chief executive of free peer-to-peer internet censorship circumvention software Lantern, said VPNs are particularly vulnerable to blocking because censors can easily target their protocols.
In contrast Lantern uses a combination of peer-to-peer overseas connections and tunnelling traffic through services censors don't want to block.
"To me this is an ongoing battle with continuing innovation on both sides. The Great Cannon attacks on GitHub were a fascinating new development reflecting the People's Republic of China's interest in exerting pressure in very targeted fashion," he said.
Another method of exerting censorship is to delete content on social media sites. However, according to a source, codewords are regularly used to get round censors on China's Whatsapp equivalent WeChat. The service now has 500 million active users, raising the question of how practical it is becoming to police.
Fisk said: "I definitely think there's a danger of being too optimistic, but [ultimately] the government is fighting a battle against hundreds of millions of people who have a fundamental desire to access information and programmers who have a fundamental desire to innovate."
"Over the long term I think the latter will clearly win, but it's unclear how long it will take," he added.
Smith agreed: "[We] believe that a combination of technological solutions and widespread adoption of these tools will make free access to information so commonplace that the authorities decide that there is no point in fighting back." ®