Abstract: IP geolocation determines the geographic location of network devices based on their IP addresses,which are the identifications of Internet devices.Landmark is a key factor in IP geolocation.Prior methods use home PC_S,web servers as well as common routers as landmarks,they produce erroneous results due to changeable IP addresses,inconsistent density as well as complicated geometric relations between time delay and distance.Traceroute command is able to find all the routers between a probe and the target host.This paper proposes a new method named Last-hop Router Based Geolocation method(LRBG).The last-hop rou-ter in a traceroute path is used as the landmark.The problem is solved by two steps.The first step is to employ the fixed Internet users within the range of a last router's delivery to infer its location.The second step is to identify the geographic location of target host based on the relation between the target host and the last hop router.The experiment results show that the LRBG me-thod achieves street-level geolocation of IP address with an average accuracy of 3.17 km.

Key words: IP geolocation, Landmarks, Network measurement, Position measurement, Router geolocation