Chinese dissidents say that despite the government's best efforts to stop them, they are successfully using the internet to spread their messages ever more widely through the world's most populous country.
The communist authorities have tightened controls on access to the web and imprisoned growing numbers of people for setting up websites or exchanging emails on sensitive topics, Amnesty International reported this week.
But despite the help of several major international corporations and the use of the most sophisticated equipment, the Chinese government is finding the worldwide web much harder to censor than traditional media.
The net is proving increasingly difficult to police
"The more they do to block it, the more people want to get online," said Liu Xiaobo, who spent years in detention after leading a hunger strike in 1989 in support of the student democracy protesters on Tiananmen Square.
The young and educated are no longer taking to the streets, but many are these days sitting in internet cafes, braving police monitors to take part in a new, virtual civil society that links them both to the outside world and to each other.
"More and more, they're taking the chance to talk about politics and democracy", Liu told BBC News Online from his home in Beijing.
The government needs the internet as an integral part of China's economic opening up, but consistently tries to block anything it dislikes, stepping up its efforts during major events such as the National Party Congress, he said.
"They send messages to servers, telling them to be extra careful ... and shut down chatrooms, bulletin boards and personal websites on which people have pasted up material from foreign media.
"One site has been shut down thirty times," said Liu.
"But after a month or two they open up again. You can't shut them down completely."
Filters are used to screen out items containing certain pornographic or politically sensitive terms, such as 4 June (the date of the Tiananmen Square crackdown), human rights, independent Taiwan or Tibet, and Falun Gong.
Members of the banned spiritual movement, which runs dozens of websites from outside China, said new ways are constantly being found to thwart the various tactics employed by tens of thousands of official internet monitors.
"People in mainland China who get onto a sensitive site like ours find they can be reached within minutes by police and their computer automatically disabled," said Sophie Xiao, a spokesperson for Falun Gong in Hong Kong.
"But we try to get our message through this blockade by all sorts of means, such as emails, chatrooms and proxy servers".
Chinese surfers have become skilled at finding proxy or intermediary websites that let them evade the so-called Great Red Firewall to reach a certain blocked site. But the authorities soon learn of these secondary sites and block them too.
Human rights groups have accused major foreign companies of helping the Chinese
government crack down on freedom of expression and information.
Reporters Without Borders said it wrote early last month to the heads of 14 suppliers of computer and internet equipment, asking them to take a stand against the Chinese government's "repression of the internet," but had yet to receive a single reply.
The Paris-based media watchdog accused two companies in particular - one of supplying special online spying systems to China, and the other of agreeing to change its portal and search-engine to facilitate censorship in exchange for access to the Chinese market.
The Chinese authorities sometimes succeed in creating a climate of self-censorship because people are uncertain about what is or is not permitted, said Sara Davis of Human Rights Watch in New York.
"If you monitor a Chinese chatroom you can see all sorts of messages about issues ranging from forced evictions of migrants to constitutional reform.
"Then comes a warning, saying 'Please stop this'".
Sometimes a message will appear such as 'Down with the Government'. It will be promptly removed, she says.
Although some subjects are still taboo, many of these internet discussions, bulletin boards and petitions have given birth to grassroots groups. Sometimes they succeed in having their causes taken up in the mainstream media, and even changing government policy.
The fact that the internet is so hard to control has also given it a role in making other media more open, according to Liu Xiaobo.
"People judge newspapers on whether they can keep up with the internet", he said.
No matter how sophisticated its technology there is no way the government can fully control the internet, according to Liu Qing, a prominent dissident who left China after his release from jail in 1992, and who is now chairman of the US-based Human Rights in China.
"People in China now understand a lot more about what's going on than when I was there in the '70s and '80s. Then, the only contact we had with the outside world was through meeting the very occasional foreigner or somehow getting hold of a foreign paper or magazine.
"There is no way the Government can be successful in really controlling the internet. That's why in China these days you can see all kinds of organisations and activities springing up, moving the country towards real change," he said.