OpenNet Initiative. Internet Filtering in Iran in 2004-2005: A Country Study. 9 Apr. 2009.

This repotr by the OpenNet Initiative is a thorough analysis of the internet filtering technology used in Iran. The study begins with a detailed description of the regulation and censorship restrictions in place both in print media and online. Then, the ONI attempts to study the Iranian filtering system. Through accessing remote computers behind Iran's firewalls, the ONI tested a list of websites to see whether they would be accessible or not. They try this technique on multiple computers and do it several different times in order to get an understanding of how consistently a certain website is blocked. Through analyzing the content of HTTP headers and web site loading time, researchers separated sites into four categories: unfiltered, possibly filtered through redirection, possibly filtered with a possible network connection error, and definitively filtered. In Iran, researchers concentrated on two ISPs: the private ParsOnline and the state-owned TCI. Results showed that only one-third of websites tested were blocked. Sites with pornographic material or that provided access to circumvention tools was filtered more successfully. Over the testing period of a year, filtering increased, particularly the filtering of blogs.

This study is perhaps the only empirical study that tests the regulation mechanism in Iran. By providing details of the filtering software and giving empirical data, readers get a clearer picture of the breadth of content that the Iranian government seeks to block. The filtering in Iran appears to be at a sophisticated level, moving beyond pornographic content that violates Islamic law and focusing on more personal forms of expression, such as blogs. One interesting result, however, is that non-Iran specific sites or non-Farsi content is harder for the filtering software to block. Still, the software in place results in an "overbreadth" of sites being blocked, censoring more forms of expression than needed/