A Look at the Consequences of Internet Censorship Through an ISP Lens

Abstract

Internet censorship artificially changes the dynamics of resource production and consumption, affecting a range of stakeholders that include end users, service providers, and content providers. We analyze two large-scale censorship events in Pakistan: blocking of pornographic content in 2011 and of YouTube in 2012. Using traffic datasets collected at home and SOHO networks before and after the censorship events, we: a) quantify the demand for blocked content, b) illuminate challenges encountered by service providers in implementing the censorship policies, c) investigate changes in user behavior (e.g., with respect to circumvention) after censorship, and d) assess benefits extracted by competing content providers of blocked content.

Topics of Controversy: An Empirical Analysis of Web Censorship Lists

“…Social media in particular stands out, consistent with external evidence that this is increasingly seen as a threat by censors [23]. Blocking access to video-sharing and other entertainment sites may also be meant to suppress copyright infringement and/or support local businesses over global incumbents [37].…”

“…In some cases, it has been possible to identify the specific "filter" in use [20,34]. Another line aims to understand what is censored and why [1], how that changes over time [3,28], how the degree of censorship might vary within a country [68], and how people react to censorship [37,38].…”

“…A few studies have dug into "leaks" of inside information, which allow researchers to see what actually is censored and perhaps why. Recently this has occurred for backbone filters in Syria [15] and Pakistan [37], and the TOM-Skype chat client's internal keyword filter [38]. However, all of these studies still took the list as a means to an end, not an object of research in itself.…”

No Encore for Encore? Ethical Questions for Web-Based Censorship Measurement

“…In another instance, a hacktivist group leaked 600 gigabytes of log files of Internet filtering devices used in Syria, allowing researchers to gain insights into censorship in that country [27]. Similarly, an anonymous ISP in Pakistan provided researchers access to a trove of data that enabled analysis of Pakistani censorship [28].…”

Ultrasurf Traffic Classification: Detection and Prevention

“…The results showed that in both events a significant increase in encrypted traffic occurred shortly after the imposition of the censorship. Additionally, a notable drop in the use of the local DNS resolvers arose, indicating that different anti-censorship techniques were employed [19].…”