HEN the reports started trickling out in early September, they were met with disbelief and then outrage among technophiles. The Chinese government had blocked its citizens from using the popular search engine Google by exercising its control over the nation's Internet service providers.

The aggressive move surprised Nart Villeneuve, a 28-year-old computer science student at the University of Toronto who has long been interested in Chinese technology issues. Blocking one of the most popular sites on the Internet was a far cry from Beijing's practice of restricting access to the Web sites of dissident groups or Western news organizations.

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From his research, Mr. Villeneuve knew that the Chinese firewall was less a wall than a net. It was porous, and the holes could be exploited. So he sat down at his home computer and within three hours had created the basics of a program that would enable Chinese Internet users to get access to Google through an unblocked look-alike site.

"It's a very simple solution," Mr. Villeneuve said. "It's kind of crude, but it works."

Mr. Villeneuve considers himself a "hacktivist" - an activist who uses technology for political ends.

"I think of hacktivism as a philosophy: taking the hacker ethic of understanding things by reverse engineering and applying that same concept to traditional activism," he said.

He takes part in Hacktivismo, a two-year-old group of about 40 programmers and computer security professionals scattered across five continents. It is just one of a handful of grass-roots organizations and small companies that are uniting politically minded programmers and technologically asute dissidents to combat Internet surveillance and censorship by governments around the globe, including those of Saudi Arabia, Myanmar, Laos, Yemen and the United Arab Emirates as well as China.

Some protect the identities of computer users in countries where Internet use is monitored closely. Others are creating peer-to-peer networks that allow for anonymous file sharing. Some have taken established techniques for encrypting data and made them easier to use. Still others are adopting techniques used by commercial e-mail spammers to send political e-mail messages past restrictive filters.

"They are computer scientists who have principled causes," said Ronald J. Deibert, an associate professor of political science at the University of Toronto who has studied the activities of such groups and runs the Citizen Lab, a political science technology laboratory that supported Mr. Villeneuve's work. "They are developing technologies not for commercial purposes, but for political purposes."

One group, the Freenet Project, has built an anonymous file-sharing network from which Internet users can download anti-government documents without fear of reprisal. Dynamic Internet Technology, a small company in Asheville, N.C., provides technical services to efforts by the Voice of America to get e-mail newsletters into China, using spammers' techniques like altering subject lines or inserting odd characters in key terms (like "June{tilde}4,'' the date of the crackdown on protests in Tiananmen Square in 1989). Chinese Internet service providers use filters that scan e-mail for such politically sensitive terms.

SafeWeb, a maker of networking hardware in Emeryville, Calif., that has drawn some financing from the Central Intelligence Agency, recently provided free software called Triangle Boy that protected Internet users' identities by routing their browsing through SafeWeb's server. The service was popular in Saudi Arabia, the United Arab Emirates and China but has been suspended for lack of money.

Mr. Villeneuve's project, which he calls a "pseudoproxy,'' is fairly simple. A computer user in China who knows the right Web address - usually learned through word of mouth - can visit the Google look-alike site on unblocked computers that run Mr. Villeneuve's software. Those computers call upon Google's servers and return the search results to the user.