TAIPEI (TheStreet) -- China's increasingly foolproof campaign to block sensitive Internet content stifles business growth, the usual argument goes.

But who's stifled depends on whose business it is. Some people are growing because of China's Great Firewall.

The firewall has been fortified largely in secret. China's 30,000 Internet police won't come out and say they block news from abroad or shut down Web sites that challenge Communist Party lines.

So it takes some imagination to figure out who might be making money off it.

Basically, think about who might replace banned Web sites that once satisfied restless Chinese teenagers in cybercafes, graduate student researchers or office workers in foreign firms who want to join social networking sites.

First, back to the stifling of business growth: Barriers against foreign social networking sites, such as Facebook ( FB) and Twitter, can make it hard for Chinese entrepreneurs or their staffs to do dialogue with would-be partners overseas. There's nothing like a good old Google ( GOOG) Internet search, either. But Google servers are based just offshore in Hong Kong, slowing access onshore, and monitoring of user activity by Beijing may further gum up connections.

China's growing list of government agencies that regulate the Internet knew about these risks to business development, however, so they have increased Internet speeds and fostered growth in local alternatives to the blocked foreign sites.

Market research and academic surveys find that most Chinese Net users don't need to look at blocked Web sites anymore and that even many of those who can don't. Just a sliver of the population with the English language skills and computer expertise to jump the Firewall actually cross it. Most are used to getting news or doing research via local Web sites. They e-mail friends abroad instead of socially networking.

That's where the business growth comes in. Chinese blog services, search engines, social networking sites and cloud storage are taking over where the banned foreign sites are kept out of the game.

China's homegrown Sina Weibo ( SINA) , Tencent Weibo and Renren ( RENN) have replaced banned Web sites that would allow personal spaces or blogs. On the no-go list are Facebook and Twitter and likewise YouTube. ("Weibo," incidentally, is Mandarin Chinese for "microblog.")

Sina, which came out 10 years ago as one of China's top Internet content providers, has seen its Nasdaq share price rise 23% over the past five years. Tencent has seen share prices go up an unfettered 87% since 2007. American Depositary Receipts of Renren, however, have sunk 77% over about the last year.

"Whether such Chinese services are making money is another story, but wherever they are in their development, it's safe to say that they have done much better or gotten much further than they might had they had to face not just local, but global competition," says Mark Natkin, managing director with the Beijing-based market research firm Marbridge Consulting.

China's bans on Dropbox and Google Drive have given growth space to the local Alibaba AliCloud service, for example. Its parent company, Alibaba Group, is expected to do an initial public offering this year after buying a share of a major rival, giant Silicon Valley giant search engine and Internet service provider Yahoo! ( YHOO).

With Google searches running slow and the company inert toward China after pulling plugs there in 2010 over censorship and hacking worries, Chinese-owned Baidu ( BIDU) and local peer Sogou have found plenty of users looking up information online. Baidu share prices are up 86% since 2007.

China's government also didn't build by itself the network that allows its cops to monitor who's surfing what, closing down proxies within days of their debuts and sending out self-explanatory page-cannot-be-displayed messages to users who land on banned sites. Any foreign company that helps China block and filter content would have a fat customer to depend on, but local rivals have caught up.

Hard to say where the foreign aid comes from. Cisco Systems ( CSCO) was sued in The United States last year over allegations of designing a firewall to monitor the Internet, but the Silicon Valley networking hardware maker has said it does not customize products to censor or repress people. China-based Huawei Technology makes the same kind of equipment anyhow.

Says Jeremy Goldkorn, founder of Beijing-based Internet research firm (and popular blog) "It's unlikely any American company has made any money since the early days of the Chinese Internet, in the 1990s, before Chinese companies like Huawei had the capacity to make routers and other networking equipment."

Be warned that Big Brother's keen electronic eye can give most of his Chinese content providers a limited edge in the financial markets.

The country's Internet content providers are geared toward Chinese tastes and audiences. Granted, that's a user base of more than half a billion people. But most providers are not tooled to go places globally the way Google and Yahoo can, ensuring customer diversity normally key to business survival.

Like successful firms in industries across China, Internet content providers also face competition from a growing crowd of newer, me-too ICPs.

But some clearly stand out. Twelve-year-old Baidu, for example, has gone past China with services in Arabic and Thai, plus a subsidiary in Japan. It opened a Singapore research center this to help extend its search engine and other Web services to Southeast Asia.

Tencent, started in 1999, bought a stake in U.S.-based Epic Games in June and already runs a version in English, among other languages, of its QQ instant messaging service.

No immediate need to censor their stocks from your portfolio.

This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.

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