— Geolocation of Internet hosts enables a diverse and interesting new class of location-aware applications. Previous measurement-based approaches use reference hosts, called landmarks, with a well-known geographic location to provide the location estimation of a target host. This leads to a discrete space of answers, limiting the number of possible location estimates to the number of adopted landmarks. In contrast, we propose ConstraintBased Geolocation (CBG), which infers the geographic location of Internet hosts using multilateration with distance constraints. Multilateration refers to the process of estimating a position using a sufficient number of distances to some fixed points, thus establishing a continuous space of answers instead of a discrete one. However, to use multilateration in the Internet, the geographic distances from the landmarks to the target host have to be estimated based on delay measurements between these hosts. This is a challenging problem because the rela...