Where The Light Gets In: Analyzing Web Censorship Mechanisms in India

In this work we present a detailed study of the Internet censorship mechanism in India. We consolidated a list of potentially blocked websites from various public sources to assess censorship mechanisms used by nine major ISPs. To begin with, we demonstrate that existing censorship detection tools like OONI are grossly inaccurate. We thus developed various techniques and heuristics to correctly assess censorship and study the underlying mechanism used by these ISPs. At every step we corroborated our finding manually to test the efficacy of our approach, an exercise largely ignored by several others. We fortify our findings by adjudging the coverage and consistency of censorship infrastructure, broadly in terms of average number of network paths and requested domains the infrastructure censors. Our results indicate a clear disparity among the ISPs, on how they install censorship infrastructure. For instance, in Idea network we observed the censorious middleboxes in over 90% of our tested intra-AS paths, whereas for Vodafone, it is as low as 2.5%. We conclude our research by devising our own novel anti-censorship strategies, that does not depend on third party tools (like proxies, Tor and VPNs etc.). We managed to access all blocked websites in all ISPs under test.