It is well known that at a global scale Internet routing is based on ASes and their relationships, not based on geopolitical properties of the networks they traverse. As a result, it is common for Internet traffic to traverse international borders, with potential implications for privacy, security, and efficiency. While there is significant prior work that identifies the ASes traversed by Internet paths and on geolocating end hosts, there is little work that focuses on identifying the geolocations of \emph{routers} along the paths and their implications.

Passport sheds light on this issue by measuring how and when Internet traffic traverses national boundaries. To do this, we use machine learning to combine individually noisy information sources, and measurements issued from hundereds of vantage points to provide a reliable location prediction. By providing Passport with traceroutes and IP addresses, you will help us understand if and how Internet paths traverse national boundaries, even when two endpoints are in the same country. And we'll show you these paths, helping you to understand where your Internet traffic goes.