CITP on the Road:
Nick Feamster – Global Measurements of Internet Censorship

CITP on the Road

Date: Wednesday, May 17, 2017
Time: 10 a.m. – 11 a.m.
Location: The Center for Democracy and Technology, 1401 K Street NW, Suite 200, Washington, DC 20005-3497

This event is made possible by generous support from the Princeton University Jerome C. Blum Memorial Fund established by Ronald D. Lee ’80 in honor of Jerome C. Blum, Professor of History, Princeton University (1947-1981).

Internet users in many countries around the world are subject to various forms of censorship and information control. Despite its widespread nature, however, measuring Internet censorship on a global scale has remained an elusive goal. Internet censorship is known to vary across time and within regions (and Internet Service Providers) within a country. To capture these complex dynamics, Internet censorship measurement must be both continuous and distributed across a large number of vantage points. To date, gathering such information has required recruiting volunteers to perform measurements from within countries of interest; this approach does not permit collection of continuous measurements, and it also does not permit collection from a large number of measurement locations; it may also put the people performing the measurements at risk.

Over the past four years, we have developed a collection of measurement techniques to surmount the limitations of these conventional approaches. In this talk, I will describe three such techniques: (1) Encore, a tool that performs cross-origin requests to measure Web filtering; (2) Augur, a tool that exploits side-channel information in the Internet Protocol (IP) to measure filtering using network-level access control lists; and (3) a tool to measure DNS filtering using queries through open DNS resolvers. These three tools allow us—for the first time ever—to characterize Internet censorship continuously, from hundreds of countries around the world, at different layers of the network protocol stack. Each of these techniques involves both technical and ethical challenges. I will describe some of the challenges that we faced in designing and implementing these tools, how we tackled these challenges, our experiences with measurements to date, and our plans for the future. Long term, our goal is to collaborate with social scientists to bring data to bear on a wide variety of questions concerning Internet censorship and information control; I will conclude with an appeal to cross-disciplinary work in this area and some ideas for how computer scientists and social scientists might work together on some of these pressing questions going forward.

This research is in collaboration with Sam Burnett, Roya Ensafi, Paul Pearce, Ben Jones, Frank Li, and Vern Paxson.


Nick Feamster is a professor in the Computer Science Department at Princeton University and the deputy director of the Princeton University Center for Information Technology Policy (CITP). Before joining the faculty at Princeton, he was a professor in the School of Computer Science at Georgia Tech. He received his Ph.D. in computer science from MIT in 2005, and his S.B. and M.Eng. degrees in electrical engineering and computer science from MIT in 2000 and 2001, respectively. Nick’s research focuses on improving the security and performance of communications networks with systems that draw on advanced Internet measurement, data analytics, and machine learning. Nick is an ACM Fellow. Among other awards, he received the Presidential Early Career Award for Scientists and Engineers (PECASE) for his contributions to cybersecurity, the Technology Review 35 “Top Young Innovators Under 35” award, and the ACM SIGCOMM Rising Star Award.