Omani users subject to India’s content filtering due to “upstream filtering”

New research from our colleagues at the OpenNet Initiative and Citizen Lab demonstrates how one country’s Internet content filtering can have a significant impact on other countries.  Researchers discovered an example of “upstream filtering” in which content filtering by ISPs in India is restricting content access for customers of Oman’s ISP because of ISP routing arrangements.

When ISPs restrict content, often at the behest of governments, their target is typically domestic audiences.  However, as the Citizen Lab and OpenNet Initiative report suggests, content filtration can migrate across borders when ISPs engage in peering or transit agreements.  Peering is when ISPs enter into an agreement to exchange traffic, allowing them to route data to places on both of their networks.  If ISPs engage in peering agreements with providers who filter the connection they use to peer, then the content filtration can also be transferred.

Because both Oman and India have domestic filtration systems in place, there is a clear risk for upstream filtering.   The OpenNet Initiative’s previous research shows that Oman blocks pornographic material, gay and lesbian sites, and anonymizing or proxy circumvention tool websites.  In contrast, India tends to filter security and Internet tools-related content. Oman’s sole ISP, Omantel, has a number of peering agreements with ISPs in India.

How did researchers conclude that users in Oman were being subjected to Indian content filtration?  The key was the different splat pages provided by Indian and Oman ISPs.  Over a ten-day period in June 2012, researchers accessed the Omantel network through proxies in order to test a list of several hundred URLs suspected to be blocked.  The list included URLs that are suspected of being blocked by Indian ISPs.  Blocked URLs were then manually tested by users in Oman.  Pages blocked by Omantel contained a message informing users that “this site has been blocked due to content that is contrary to the laws of the Sultanate.”  However, a number of blocked URLs contained a different message: “This website/URL has been blocked until further notice either pursuant to Court orders or on the Direction issued by the Department of Telecommunications.”  Forty one URLs from the list resulted in this message.  According to ArsTechnica, “the sites affected included Indian and Pakistani entertainment sites, political blogs, file-sharing websites, and even IndyBay, a San Francisco-based online news site.”

Researchers believe this message is a result of content filtering in India partially because India’s telecommunications regulator is the Department of Telecommunications, while Oman’s regulator is called the Telecommunications Regulatory Authority. Many of the blocked URLs are music and file-sharing sites relating to Bollywood movies and music, which are often blocked in India.  In one example, a request from Oman for an Indian music and movie download site hosted in the United States was blocked because the traffic passed through an Indian ISP, Bharti Airtel.

While this is not the first instance documented of upstream filtering, researchers conclude the practice “raises a number of questions, including jurisdictional issues and the lack of recourse available to users in Oman.” In essence, Omani Internet users are subject to several layers of filtering, not all of which is within their country.

Read the full Citizen Lab/Open Net Initiative report here.