Analysis of country-wide internet outages caused by censorship

TLDR

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. The study analyzes episodes of internet disruptions in Egypt and Libya and proposes an automated methodology for detecting similar outages elsewhere. The authors combined BGP control‑plane data, unsolicited data‑plane traffic, traceroute measurements, RIR delegation files, and MaxMind geolocation to map IP ranges to entities, associate them with BGP prefixes and ASes, and analyze activity during the censorship episodes. Combining control‑plane and data‑plane datasets enabled the authors to identify the specific forms of internet access disruption over time and revealed that Libya first tested firewall‑based blocking before deploying more aggressive BGP‑based disconnections.

Abstract

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.