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Internet Filtering: Regulating Content

By | February 1, 2013

      Internet filtering is such a growing practice among world nations that the question today is not whether countries filter the Internet, but to what extent. Satellite links often provide connectivity for Internet backbones linking to international gateways. It is at these ports of entry that certain governments place Internet filters. In other instances, governments delegate Internet filtering to national Internet Service Providers (ISPs). This article discusses the reasons and the mechanics for national Internet filtering; the debate that arises as a result of such practices; and the importance of these issues for the telecommunications industry.


      The Reasons for Internet Filtering

      In countries where the Internet is filtered, the practice is usually an extension of regulations limiting verbal and written expression. Interestingly, it is not only nations like China and Iran that filter the Internet. There is also government mandated filtering in European democracies as well as in the United States.

      Countries almost universally agree that certain Internet content is unacceptable, such as in the case of sites promoting child pornography, phishing or fraud. Filtering other types of content is usually politically or culturally driven; be it to suppress political dissent, undermine religious minorities, or prevent the proliferation of ideas advocating women’s rights.

      There are three primary ways of filtering: IP header filtering, IP payload filtering and Domain Name System (DNS) filtering. Routers performing IP header filtering read IP addresses contained in IP headers. The website IP address is then compared with a blacklist of IP addresses. Whenever a match is found, the packets are dropped. This type of filtering can significantly overblock sites because one IP address can host thousands of websites. Another problem with this method is that it is impossible to keep a blacklist updated.

      IP payload filtering is more accurate because it filters based on key words rather than IP addresses. However, additional equipment may be needed to perform deep packet inspection. Whenever the equipment identifies a phrase of interest (e.g., “Tiananmen Square Massacre”), IP packets are dropped. While this method is more accurate, overblocking can still occur. Also, the additional equipment must be fast enough to review packet content in real time. Lastly, DNS filtering prevents users from resolving their domain name query to the respective IP address. DNS filtering, also based on blacklists, targets the domain name rather than the IP address.


      Filtering Issues

      When filtering is done, other issues ensue. For example, is the country transparent about what it is filtering as well as its reasons for doing it? Most countries, upon blocking a site, give the impression that there was some kind technical error getting to the site. Other countries involve the citizenry in the filtering process by encouraging people to submit blocking suggestions.

      Another important issue is whether ISPs have the power to carry out filtering policy on their own or must they act only by court order? The former approach has led to ISPs misapplying the policy and blocking unintended sites.


      The Free Speech Argument

      The free speech argument says that as long as there is the possibility for overblocking, government mandated Internet filtering infringes constitutionally protected speech. In the United States, the Supreme Court has struck down as unconstitutional statutes designed to filter sites with explicit materials that could be viewed by minors. Only in one instance has a statute requiring schools and libraries to place filters on computers accessible by children survived constitutional muster; and this was only because the filtering is done at the user level. Recently, the application of a statute requiring ISPs to block sites involved in copyright infringement has also been suspended.



      More regulation of the Internet is on the horizon. Currently, the Internet is governed by a private non-profit corporation. Efforts are underway to shift some Internet governance to the International Communications Union (ITU), thus bringing Internet governance to the intergovernmental level. Through all these changes, the satellite industry must not maintain a mere ‘transport’ mentality when it comes to the Internet because it is an integral part of telecommunications and will keep exerting important forces on the industry.

      Raul Magallanes runs a Houston-based law firm focusing on telecommunications law. He may be reached at +1 (281) 317-1397 or by email at raul@

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