Abstract
Internet Censorship is unceasingly increasing in many countries worldwide in order to restrict web contents within the country premises. According to latest Open Net Initiative (ONI) report, almost 50 countries are involved in web censorship, including Pakistan. This paper presents the methodology and the measurement analysis based on publicly available censored URLs in Pakistan, providing both qualitative and quantitative results to gauge how major ISPs are censoring web content in Pakistan. This is the first study in literature analyzing and comparing the behaviour of five ISPs in Pakistan using automated detection methods based on active probing measurements. Our results show that (i) WiTribe, PTCL, and Nayatel block content by using DNS tampering while (ii) Wateen and Qubee apply filtering, using HTTP tampering. We comment on these results by considering the evolution over time of the forced censorship mechanisms. Finally, we performed a University closed survey in order to find out circumvention techniques adopted by users in Pakistan and we report that Pakistani users try to evade censorship by using web proxies, Tor and VPN.