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 MaxMind.com.


require 'geoip_city'
db = GeoIPCity::Database.new('/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

GeoIPCity::Database.new(dbfile, :filesystem, true)


Some variation of the following should work.

  1. Install the GeoCity C library. You can get it from here

    www.maxmind.com/app/c 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: www.maxmind.com/app/geolitecity Maybe this direct link will work: www.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz I put this file in /opt/GeoIP/share/GeoIP/GeoLiteCity.dat

  4. Use it!


Copyright (C) 2007 Ryan Dahl ([email protected])

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