Understanding Internet censorship

Research carried out by organisations like the OpenNet Initiative (ONI) and Reporters Without Borders (RSF) indicates that many countries filter a wide variety of social, political and 'national security' content, while rarely publishing precise lists of what has been blocked. Naturally, those who wish to control their citizens' access to the Internet also make a special effort to block known proxies and websites that offer tools and instruction to help people circumvent these filters.

Despite the guarantee of free access to information enshrined in Article 19 of the Universal Declaration of Human Rights, the number of countries engaged in Internet censorship has continued to increase dramatically over the past few years. As the practice of Internet filtering spreads throughout the world, however, so does access to the circumvention tools that have been created, deployed and publicised by activists, programmers and volunteers.

Before exploring the various ways to bypass Internet censorship, you should first develop a basic understanding of how these filters work. In doing so, it may be helpful to consider a greatly-simplified model of your connection to the Internet.

Your Internet connection

The first step of your connection to the Internet is typically made through an Internet Service ProviderISP at your home, office, school, library or Internet cafe. The ISP assigns your computer an IPaddress, which various Internet services can use to identify you and send you information, such as the emails and webpages you request. Anyone who learns your IP address can figure out what city you are in. Certain well-connected organisations in your country, however, can use this information to determine your precise location.

• Your ISP will know which building you are in or which phone line you are using if you access the Internet through a modem.
• Your Internet cafe, library or business will know which computer you were using at a given time, as well as which port or wireless access point you were conncted to.
• Government agencies may know all of these details, as a result of their influence over the organisations above.

At this stage, your ISP relies on the network infrastructure in your country to connect its users, including you, with the rest of the world. On the other end of your connection, the website or Internet service you are accessing has gone through a similar process, having received its own IP addresses from an ISP in its own country. Even without all of the technical details, a basic model like this can be helpful when considering the various tools that allow you get around filters and remain anonymous on the Internet.

How websites are blocked

Essentially, when you go to view a webpage, you are showing the site's IP address to your ISP and asking it to connect you with the webserver's ISP. And, if you have an unfiltered Internet connection, it will do precisely that. If you are in a country that censors the Internet, however, it will first consult a blacklist of forbidden websites and then decide whether or not to comply with your request.

In some cases, there may be a central organisation that handles filtering in place of the ISPs themselves. Often, a blacklist will contain domain names, such as www.blogger.com, rather than IPaddresses. And, in some countries, filtering software monitors your connection, rather than trying to block specific Internet addresses. This type of software scans through the requests that you make and the pages that are returned to you, looking for sensitive key words and then deciding whether or not to let you see the results.

And, to make matters worse, when a webpage is blocked you may not even know it. While some filters provide a 'block page' that explains why a particular page has been censored, others display misleading error messages. These messages may imply that the page cannot be found, for example, or that the address was misspelled.

In general, it is easiest to adopt a worst-case perspective toward Internet censorship, rather than trying to research all of the particular strengths and weaknesses of the filtering technologies used in your country. In other words, you might as well assume that:

• Your Internet traffic is monitored for keywords
• Filtering is implemented directly at the ISP level
• Blocked sites are blacklisted by both their IP addresses and their *domain names *
• You may be given an unclear or misleading reason to explain why a blocked site fails to load.

Because the most effective circumvention tools can be used regardless of which filtering methods are in place, it does not generally do any harm to make these pessimistic assumptions