How to do offline geo-lookups of IP addresses

• Posted 19 January 2024
• Tagged with networking, python

MaxMind offer databases you can do to look up IP addresses without sending the address off to a remote service.

I was experimenting with web analytics, and I wanted a way to look up the country for an IP address – in a privacy-preserving way.

There are lots of web APIs for doing IP address lookup, e.g.

$ curl "https://api.ipregistry.co/1.2.3.4?key=tryout"

These are suitable for certain one-off tasks, but you’re sending the IP address off to a third-party service. If I use this in an analytics package, I’m handing a complete list of visitor addresses to this service. Ick!

(Plus making an HTTP request for each IP address probably introduces lots of latency.)

A Stack Overflow answer pointed me at MaxMind. I was able to download a free country database from their site, which is about 6.4MB in “MaxMind DB” format – a database format designed for fast IP address lookups.

I can then use the maxminddb Python library to open the database and look up IP addresses:

import maxminddb

with maxminddb.open_database('GeoLite2-Country_20240116/GeoLite2-Country.mmdb') as reader:
    print(reader.get('52.85.118.55'))
    # {'continent': {'code': 'NA', 'geoname_id': 6255149, …

Note that this method can sometimes return None, if the IP address isn’t in the database – or in this case, if it’s an IP address reserved for testing purposes.

with maxminddb.open_database('GeoLite2-Country_20240116/GeoLite2-Country.mmdb') as reader:
    print(reader.get('192.0.2.0'))
    # None