Reverse-Engineering the Internet

The Internet is a network of competing networks. Independent network operators have access to the proprietary details of their own networks, but neither researchers nor network operators have had access to the detailed, global picture of the Internet needed to find and correct network vulnerabilities and evaluate new applications and protocols. My thesis work demonstrates that detailed topological and routing information regarding the global Internet and its constituent networks is within the reach of these communities. That is, that reverse-engineering the Internet can be made practical through innovative measurement and inference techniques. In this talk, I present my Rocketfuel system which efficiently maps networks in the Internet using only externally available information. To recover a reasonably complete network graph, Rocketfuel uses hundreds of traceroute servers as vantage points to collect paths through the network. For efficiency, Rocketfuel uses global routing information and prior measurements to guide further measurement. To give the maps structure, Rocketfuel uses the information encoded in router names to assign each router to a geographic location and uses the rest of the network graph to determine the role of each router in the network. Topology is only part of the picture; the rules that govern how packets are directed across the topology are equally important but impossible to measure directly. I will describe how routing can be inferred from paths not taken. Inferred routing allows us to summarize and predict which path a packet will traverse, as well as to find interesting configuration decisions. Understanding global Internet topology and routing allows operators to predict the effects of change and allows researchers to identify problems and demonstrate the effectiveness of their solutions using realistic Internet topologies.