Autonomous System Choke Points In Country-Level Network Topology

Internet traffic choke points within country-level logical networks exist at the Autonomous System (AS) level, with consequences and implications for country-level network topology and vulnerability to network disruption or surveillance. This thesis introduces the concept of such Gateway ASs, which serve to connect the logical interior of a given country's network to the larger internet, and further demonstrates it to be a well-defined and useful concept. By fully characterizing the prevalence and nature of these Gateway ASs across the internet as a whole, this study demonstrates that the internet remains highly hierarchical at the country-level, despite the internet's evolutionary trend towards a flattened topology. Further, this conception and characterization of country-level network topology is leveraged to map vast portions of the logical internet landscape to physical country borders, but ultimately fails to provide an accurate and complete heuristic for internet infrastructure geolocation based upon logical AS classification. Finally, this study provides an assessment of the countries most susceptible to censorship events based upon the structure of their network topology, and quantifies an upper bound (by percentage of available IP space within the geographic confines of the country) for the effectiveness of such censorship schemes to fully sever network connectivity with the larger internet.