Facing student protests ahead of today's National Students Day — the anniversary of three student deaths in Tehran in 1953 — the state-owned Telecommunication Company of Iran (TCI) slowed or blocked completely access to the Internet for most of the state

The Internet may be a worldwide superhighway, but it's all to easy to shut it down. Governments aiming to squelch free speech in don't even have to work hard to do so: It's all too easy to restrict the Internet and keep their people in the dark.

The practice is all too too easy, and all too common.

First, the government talks to the major Internet Service Providers (ISPs) that control the flow of data in and out of the country. Not every country has the wide array of ISPs we have in the United States. In many countries, people get online through a limited selection that are authorized to work in the country.

For example, there were only nine ISPs controlling the physical lines connecting China to the outside world in 2002, according to a BBC report at the time. That makes it much simpler for the regime to control information.

And China is well known for restricting access to the Internet for its citizens, a project the country calls "the Golden Shield." The rest of the world calls it the Great Firewall of China. With the agreement and help of those ISPs, the government can control traffic through a variety of techniques, including filters that control certain words, blocks in specific domains or users, even by blocking entire domains (such as .com or .net).

"Governments can censor Internet traffic using the same technology tools found in large corporate enterprises," explains PCMag.com lead networking analyst Samara Lynn. "Sophisticated security and network management appliances and software can be used to block specific keywords or categories from Internet searches, and they can perform DNS blocking and Web filtering."

Keyword blocking prevents people from searching for such obviously dangerous words as "freedom" and "democracy." Custom black lists also server to block content that specifically rankles the government. Is it unions, student protests or something else?

When the government catches someone searching for these terms, they can automatically turn off their access for a period of time. "If a user happens upon a site or search result that has been flagged unacceptable, that user’s connection to the Internet can be dropped altogether for a specified period of time," notes PCMag.com's Lynn.

Beyond the technical, these regimes rely upon a hand-picked group to police access. The Iranian police recently created a special 12-member Internet police unit charged with acting "against fraud attempts, commercial advertising and false information" and hunting down "insults and lies."

Police Col. Mehrdad Omidi, who heads the Internet crime unit, specifically said that the 12-member unit will intervene in "political matters on the Internet should there be an illegal act." The official said the unit will operate under the direction of the prosecution office.

Local activists often struggle to work around these restrictions. During the recent Iranian election scandal, activists turned to social networks like Twitter and Facebook to spread information the government would otherwise oppress.

"I think the Iranian government is learning quickly how to control and contain these things," Andrew Lewman, executive director of The Tor Project Inc., told the Associated Press.

His group's free downloadable Tor program allows Internet users to work through a network of relays run by volunteers around the world to access blocked sites and hide what they are doing on the Internet. Active sessions using Tor in Iran have jumped from a few hundred before the election to thousands after, the nonprofit group said.

Other governments are actively trying to help out as well. In July, the U.S. Senate approved the Victims of Iranian Censorship (VOICE) Act, which Congress hopes will strengthen the ability of the Iranian people get access to news and information and overcome the electronic censorship and monitoring efforts of the Iranian regime.

The bill authorized $30 million to support free radio broadcasts worldwide; $20 million to development technologies and Websites that will let Iranians gain access information; a report by the President on non-Iranian companies that have aided the Iranian government's Internet censorship efforts; and more.

If you're interested in helping out, there are several things you can do:

* Support Voice of America, the U.S. government funded radio station that broadcasts to over 125 million people a week.

* Post information about current proxies on your Web site. Proxies allow people to circumvent content filters; a list is updated weekly at VOANews.com.

* Spread the word about Freegate, software that lets people living in areas that restrict access view blocked sites.