When your packets travel through the Internet, where exactly do they go? How many users of your web site live in Europe? How will your Internet service be affected by a new trans-pacific cable? To answer these questions you need geographic information. Internet researchers frequently need to map their observed data to specific places. But IP addresses, Autonomous System numbers, and hostnames are values in a logical hierarchy; they contain no geographic information. There is no authoritative database for mapping these identifiers to locations, so several sources of network information must be used, and these sources may be conflicting or incomplete. The large size of the typical data set used in Internet research makes manually mapping many thousands of IP addresses to locations impractical and imprecise; an automated solution is required. In this paper we describe NetGeo, a tool that overcomes these obstacles.

NetGeo is a tool that maps IP addresses, domain names, and Autonomous System (AS) numbers to geographic locations. NetGeo has significant potential to support a variety of tasks: automatic selection of geographically nearby mirror sites; ISP decisions on where to deploy new infrastructure, traffic flow analysis for tariff policy research; regionally-based advertising design, etc. NetGeo is currently being used both in a graphical traceroute tool and for studies of connectivity and traffic flow between countries.

NetGeo can be accessed interactively via the web and through Java and Perl APIs. The NetGeo back-end consists of a database and a collection of Perl scripts for address parsing and heuristic analysis of whois records. To reduce the load on whois servers and to improve performance, NetGeo caches geographic information parsed from previous queries.

Prior to the development of NetGeo, Internet geographic information was not easily available. We look forward to many creative uses of this tool as researchers become aware of its availability.