Tunisia uses commercial filtering software called SmartFilter , which is produced by the U.S. company Secure Computing, to filter Internet access in Tunisia. This software is configured to blocked pre-defined categories of content – content classified by SmartFilter – including at least four SmartFilter categories: Anonymizers, Nudity, Pornography, and Sexual Materials.
Tunisia’s Internet filtering is done in a non-transparent way. When users attempt to access a blocked page, they are not informed that the page is filtered, but instead merely receive a standard error message, a 404 “File Not Found” error. However, the actual HTTP header, is not a 404, but a 403 Forbidden error generated by the filtering system SmartFilter, in conjunction with NetCache caching servers. SmartFilter can be configured with a blockpage that indicates to users that the site has been blocked and why, however, unlike other countries using this exact same filtering system, Tunisia has copied the text from the Internet Explorer 404 page, and used this as a blockpage to make the filtering appear to be an error.
(See Astrubal’s detailed explanation here).
Recently, the video-sharing web site dailymotion.com was blocked in Tunisia. It was blocked because SmartFilter categorized the web site as pornography, and, since Tunisia blocks the pornography category the web site was blocked. Some time bewteen April 4, 2007 and April 9, 2007 SmartFilter removed dailymotion.com from the pornography category.
It is being reported that access to the site is available through at least one ISP in Tunisia. Depending on how frequently the various filtering and cache server’s update there wil likely be some variation acroos ISPs for sometime. Eventually, full acess should be restored. (Tunisia could, as they do with a varity of other content including humrn rights information, add the website as a custom url on top of their SmartFilter categories and intentionally block the site if they choose to do so).
This is a very significant case as it demontrates how the decisions made by filtering companies affect Internet access in entire countries.