Shuimu.com is just one of China's thousands of Internet chat rooms. But when non-students were barred this month from using the site at Tsinghua University in Beijing, it triggered a rare burst of outrage.
A brief protest erupted at the school. Users posted appeals on other sites for Web surfers to speak up. Some compared the crackdown to persecution in Nazi Germany.
Until a few days ago, Shuimu was the biggest university forum in China. For 10 years, students, alumni and others used it for lively debates on everything from physics to politics.
Now, in a crackdown aimed at preventing critics from posting anti-government comments online, communist authorities have closed the site to users outside the university campus.
Several other top universities also posted notices on their bulletin boards this month saying users had to register. Outsiders and anonymous postings were banned.
China has the world's second-largest online population -- 87 million -- after the US. The government encourages Web use for business and education, but tries to bar access to material deemed subversive or pornographic.
Tsinghua officials told Shuimu users on March 16 that only people within the university would be allowed access to the site.
"We will never ever forget the broad community of outside users," said the notice, which has been widely circulated on the Internet.
The edict was said to come from the Ministry of Education, which did not respond to a faxed query from reporters seeking confirmation.
On March 18, students held a rare protest on Tsinghua's campus.
They laid out flowers and origami cranes and wrote "peace" and "free" on the ground with scraps of paper, according to pictures posted on San Francisco-based Web site Webshots.com.
One photo showed a banner that read "Bless and protect Shuimu."
"This country is closing itself, it's suiciding," said a caption on one of the photos.
Complaints popped up on other chat rooms and personal Web log sites, or blogs.
"I feel our channels of communication are already controlled by an invisible hand and our free breathing space is becoming smaller and smaller," said a posting signed Zola.
Others compared the crackdown to Nazi Germany, invoking a quote from a pastor who famously said that after he failed to speak up when the Nazis persecuted communists and Jews, there was no one left to speak up when the Nazis came for him.
But some criticized the outcry, saying it might jeopardize Internet access for ordinary Chinese.
"It's thanks to you people out there who are clamoring for freedom all day that we small potatoes worry that we won't even be able to use the Internet at all in the future," said a note on a bulletin board of the Web site Donews.com. It was signed "oo."