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Analysis of Country-wide Internet Outages Caused by Censorship
A. Dainotti, C. Squarcella, E. Aben, K. Claffy, M. Chiesa, M. Russo, and A. Pescapè, “Analysis of Country-wide Internet Outages Caused by Censorship'', in Internet Measurement Conference (IMC), Berlin, Germany, Nov 2011, pp. 1--18, ACM.
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Analysis of Country-wide Internet Outages Caused by Censorship

Alberto Dainotti 1
Claudio Squarcella 2
Emile Aben 3
Kimberly Claffy 4
Marco Chiesa 2
Michele Russo 1
Antonio Pescapè 1
1

University of Napoli Federico II

2

Roma Tre University

3

RIPE NCC

4

Cooperative Association for Internet Data Analysis - CAIDA

San Diego Supercomputer Center,

University of California, San Diego

In the first months of 2011, Internet communications were disrupted in several North African countries in response to civilian protests and threats of civil war. In this paper we analyze episodes of these disruptions in two countries: Egypt and Libya. Our analysis relies on multiple sources of large-scale data already available to academic researchers: BGP interdomain routing control plane data; unsolicited data plane traffic to unassigned address space; active macroscopic traceroute measurements; RIR delegation files; and MaxMind's geolocation database. We used the latter two data sets to determine which IP address ranges were allocated to entities within each country, and then mapped these IP addresses of interest to BGP-announced address ranges (prefixes) and origin ASes using publicly available BGP data repositories in the U.S. and Europe. We then analyzed observable activity related to these sets of prefixes and ASes throughout the censorship episodes. Using both control plane and data plane data sets in combination allowed us to narrow down which forms of Internet access disruption were implemented in a given region over time. Among other insights, we detected what we believe were Libya's attempts to test firewall-based blocking before they executed more aggressive BGP-based disconnection. Our methodology could be used, and automated, to detect outages or similar macroscopically disruptive events in other geographic or topological regions.

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