| Models of Internet routing are critical for studies of Internet security, reliability and evolution, which often rely on simulations of the Internet's routing system. Accurate models are difficult to build and suffer from a dearth of ground truth data, as ISPs often treat their connectivity and routing policies as trade secrets. In this environment, researchers rely on a number of simplifying assumptions and models proposed over a decade ago, which are widely criticized for their inability to capture routing policies employed in practice. This thesis makes the following two contributions:;• Investigating Interdomain Routing Policies. First we put Internet topologies and models under the microscope to understand where they fail to capture real routing behavior. We measure data plane paths from thousands of vantage points, located in eyeball networks around the globe, and find that between 14--35% of routing decisions are not explained by existing models. We then investigate these cases, and identify root causes such as selective prefix announcement, misclassification of undersea cables, and geographic constraints. Our work highlights the need for models that address such cases, and motivates the need for further investigation of evolving Internet connectivity.;• Study of attacks against decoy router deployments. Second, we use our understanding of Internet Routing and tools developed, to study the effect of decoy router deployments over the Internet and come up with a way to figure out an optimal decoy router deployment in terms of the number of deployments required, in order to target a censoring AS. We introduce the notion of Helper ASes, which are autonomous systems that do not host a decoy router in their network but help out by making specially crafted routing announcements to force traffic from censoring countries through an AS hosting a decoy router. By introducing the Helper ASes into the decoy routing ecosystem, we are able to greatly reduce the number of deployments required for the system to be effective. |
