GeoIP

GeoIP is a C library that enables the user to find the country that any
IP address or hostname originates from. It uses a file based database
that is accurate as of March 2002. This database simply contains IP blocks
as keys, and countries as values. This database should be more complete and
accurate than using reverse DNS lookups.

This module can be used to automatically select the geographically closest
mirror, to analyze your web server logs to determine the countries of your
visitors, for credit card fraud detection, and for software export controls.