Iranian Bloggers Protest Government Crackdown

Online Journalism Review has an article on Iranian bloggers and Internet filtering in Iran. The article discusses recent arrests of some bloggers and crackdown on reformist newspapers. Among others the article has some quotes from both Hossein and myself. I’ve archived the article in pdf format here.

Although I may come off as a bit pessimistic, the point I am trying to make is that technical solutions alone will not solve the problem of Internet censorship. If a determined State allocates a considerable amount of resources — human and technical — towards Internet censorship along with a repressive legal framework no technical solution alone will solve the problem. But we can analyze the specific filtering and monitoring situations that people face and work together on the development of solutions that meet the end-user’s specific needs.

Each filtering location has its own characteristics in terms of level and scale of deployment (on/near the backbone routers, at the ISP level etc…) and the technologies used to actually implement the filtering. In general, Iran’s filtering capacity, as a whole, is less than that of China and greater than that of India.

China has an advanced filtering system on/near the backbone routers that is capable of filtering in a variety of ways including keyword filtering in URL/Domains. The blocking mechanism involves the disruption of TCP connections by sending an RST (Reset) packet. This also triggers a ZeroWindow condition which prevents TCP connection from being established between the client/host for a period of time. This condition is often decribed as “being banned for period of time” — which is not
entirely accurate.

India has delegated filtering responsibility to ISP’s, not all of which are in compliance. Only two websites are blocked by official order, but due to different blocing techniques used by ISP other sites are blocked as a consequence. This collateral blocking applied (and may still with some ISP’s) to all Yahoo! Groups because India ordered one particular Yahoo! Group blocked. In addition, other websites located on the same host (virtual hosting) as are blocked as a result of a blocking order placed on Such overblocking is fairly common and occurs when sites are blocked by IP address, even though other sites are hosted on the same server.

This overblocking is similar to that described in a recent case in Pennsylvania where major Internet providers including AOL and Worldcom blocked access to nearly 1.5 million legitimate websites while trying to block access to approximately 400 websites suspected of containing child abuse images.

Iran is somewhat comparable to Saudi Arabia — with the key difference being that the Saudi system is centralized whereas Iran’s filtering is delegated to the ISP level and as such the filtering technology used, as well as what’s blocked, varies from ISP to ISP.

Iran, like Saudi Arabia, has developed their filtering capacity on top of commercial content filtering technology, the same technology used in schools and libraries in the USA.

The difference between Saudi Arabia and Iran is that different ISP’s in Iran use different commercial technology (e.g. ParsOnline uses Websense whereas NedaNET and TCI use Smartfilter). Iran’s decentralized, distributed system delegates responsibilty for filtering implementation to the ISP’s themselves. In addition to sites blocked by the commercial filtering software (mostly pornography) the government has admitted that it sends the ISP’s additional sites to block.

Testing indicates that these sites are mostly Persian/Farsi language sites critical of the regime — human rights groups, political parties, blogs, and Persian/Farsi news sites and sites that have sexual content. However, pretty much all major foreign news sites I’ve tested are not blocked. (The exception is VOA sponsored news sites, such as Radio Farda. Also, some of the Persian/Farsi websites of major foreign news outlets are targeted.)

I have observed that in Iran some sites are sometimes blocked and unblocked at various times. There does not seem to be a method to this. There is often media attention when sites are re-blocked but this fits with the general pattern of blocking/unblocking. There does not appear to be a surge of new blocking, although there have been reports that some high profile reformist sites have been blocked/shutdown recently.

Back to the issue at hand. The main issue with circumvention technology is that any publicly known system that Iranian Internet users know about, the censors will also find out about. Measures can then be taken to block the circumvention system. The key is to establish and capitalize on relations of trust between human-to-human, as oppposed to technological peer-to-peer, networks in which customized solutions can be developed and implemented to suit the specific needs to the target end-user.

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