Mending Wall: On the Implementation of Censorship in India Devashish

Abstract

This paper presents a study of the Internet infrastructure in India from the point of view of censorship. First, we show that the current state of affairs – where each ISP imple- ments its own content filters (nominally as per a governmental blacklist) – results in dramatic differences in the censorship experienced by cus- tomers. In practice, a well-informed Indian citizen can escape censorship through a judicious choice of service provider. We then consider the question of whether India might potentially fol- low the Chinese model and institute a single, government-controlled fil- ter. This would not be difficult, as the Indian Internet is quite centralized already. A few “key” ASes (≈1% of Indian ASes) collectively intercept all publicly-visible DNS servers. 5, 000 routers spanning these key ASes ≈95% of paths to the censored sites we sample in our study, and also to would suffice to carry out IP or DNS filtering for the entire country; ment is willing to employ more powerful measures, such as an IP Prefix ≈70% of these routers belong to only two private ISPs. If the govern- Hijacking attack, any one of several key ASes can censor traffic for nearly all Indian users. Finally, we demonstrate that such federated censorship by India would cause substantial collateral damage to non-Indian ASes whose traffic passes through Indian cyberspace (which do not legally come under Indian