Reporting from Beijing — Zhang Shan never paid much attention to Internet censorship in China. The stylish art gallery clerk said it didn't really matter in her daily life.
Then last year, she lost access to some of her favorite websites. First YouTube. Then Twitter. Then Facebook.
It was her first memorable brush with the so-called Great Firewall of China -- one of many powerful mechanisms the Chinese government uses to block content deemed too sensitive for the eyes of its 384 million Internet users.
"I really didn't like it," said Zhang, standing outside a popular Beijing shopping mall.
Then she cautiously lowered her voice and said, "But a friend of mine gave me a program where I can log in and I can visit all those websites again. Many of my friends are also using the same program."
Google Inc.'s threat this week to pull out of China, following a series of cyber attacks on its e-mail service that many suspect was orchestrated by the Chinese government, was a stark reminder of the limitations here on Internet freedom.
But if cyber censorship in China is a never-ending game of cat and mouse, the mice are multiplying fast. Despite increasingly aggressive government measures to tighten the flow of information and to snoop on suspected dissidents, China's resourceful netizens are finding ways to evade the country's Internet restrictions.
Known as fanqiang, or "scaling the wall," these work-arounds typically involve tapping into remote servers located outside China that aren't subject to Chinese government control. Although these skills are largely the province of tech-savvy Chinese bloggers and students, word is spreading fast about how to gain access to taboo sites.
If Google does end up leaving China, experts said, it could be a Pyrrhic victory for Beijing. The company's warning that it will exit the country rather than be party to more censorship has won praise among some Internet users here. Millions who once relied on the search engine's services may become more defiant of government controls and more motivated to learn how to get around the Great Firewall.
And recent crackdowns on social networking sites appear to be alienating some ordinary Chinese who previously showed little concern about the government's efforts to limit their access to pornography or politically sensitive material.
"The best censorship is the censorship you don't know about. But with all the recent troubles, it's becoming more public," said Xiao Qiang, director of the China Internet Project at UC Berkeley. "That undermines the goal of censorship itself. It's converting more and more people."
Authorities have tightened Internet restrictions inside China since the 2008 anti-government uprising in the autonomous western region of Tibet. The cyber crackdown escalated after ethnic riots broke out in China's restive Xinjiang province last summer, when Twitter and a similar Chinese service named Fanfou were blocked. Facebook, which reportedly had up to 400,000 subscribers in China early last year, was also forbidden. All remain off limits inside China.
Yet the Great Firewall is famously porous. Anyone who wants to evade the restrictions can do so by using a proxy server or a virtual private network, better known as a VPN.
These work by logging the Chinese computer onto a foreign server that's able to access the Internet freely. When information is bounced back to the computer in China, it's cloaked in a way to get it past government filters.
The technology has been indispensable to foreign companies operating in China such as banks that need security to conduct their business, which is why Chinese authorities allow it. But a growing number of Chinese appear to be taking advantage as well.
About a million people in China use Hotspot Shield, a free VPN with 7.5 million subscribers worldwide, a Hotspot Shield spokeswoman said.
Bill Bullock, chief executive of the VPN service WiTopia Inc., said the number of WiTopia users in China has been doubling every year and generally jumps after government crackdowns online.
Michael Anti, a well-known Chinese Internet activist, remains encouraged that the censors are losing ground. To him, there is no better example than the rise of Twitter in China.
Before the site was blocked last July, Anti said, 1,000 people were following his short posts, known as tweets. He now has 12,000 followers -- about two-thirds of whom he believes are in China using software to jump the firewall.
"China's censorship was built for Web 1.0, but everything now is Web 2.0," Anti said.
Xiao at UC Berkeley said there were an estimated 30,000 Twitter accounts in China before the service was blacklisted. That number plunged to about 10,000 after Chinese authorities blocked the site, and since then has rebounded to 50,000, Xiao said. Anti estimated the figure at 100,000.
"As far as Twitter is concerned, the Great Firewall is a failure," Xiao said.
Twitter did not respond to a request to verify the figures.