Last Update: Thu Mar 05 11:20:56 +0100 2009


This is a library which provides a single function. The function takes as input an IP address and it outputs a hash containing best-guess geographical information (like city, country, latitude, and longitude).

Actually this is only a Ruby binding to a C library which provides this function. Also, you must download a large binary database with all this mapping information. It is kindly provided free of charge by


   require 'geoip_city'
   db ='/opt/GeoIP/share/GeoIP/GeoLiteCity.dat')
   result = db.look_up('')
   p result
   # => {:city=>"Ithaca",
   #     :latitude=>42.4277992248535,
   #     :longitude=>-76.4981994628906,
   #     :country_code3=>"USA",
   #     :country_code=>"US",
   #     :country_name=>"United States",
   #     :dma_code=>555,
   #     :area_code=>607,
   #     :region=>"NY" }

There are two optional arguments to database initializer. The first argument is the filename of the GeoIPCity.dat file The second argument (optional) is to specify how GeoIP should keep the database in memory. There are three possibilities

  • :filesystem — read database from filesystem, uses least memory.
  • :index — the most frequently accessed index portion of the database, resulting in faster lookups than :filesystem, but less memory usage than :memory.
  • :memory — load database into memory, faster performance but uses more memory. (default)

The third argument is boolean and decides whether the system should reload the database if changes are made to the dat file. (You probably don‘t need this. Default: false.)

For example, :filesystem, true)


Some variation of the following should work.

  1. Install the GeoCity C library. You can get it from here For example, I like to install mine in /opt/GeoIP so I do this:
      tar -zxvf GeoIP-1.4.3.tar.gz
      cd GeoIP-1.4.3
      ./configure --prefix=/opt/GeoIP
      make && sudo make install
  2. Now install the geoip_city gem
      sudo gem install geoip_city -- --with-geoip-dir=/opt/GeoIP
  3. Download the GeoLite City database file in binary format from: Maybe this direct link will work: I put this file in /opt/GeoIP/share/GeoIP/GeoLiteCity.dat
  4. Use it!


You might need to set

  export ARCHFLAGS="-arch i386"

to be able to compile the gem.


Copyright (C) 2007 Ryan Dahl (

I give permission for you to do whatever you‘d like to do with this software.