Both Nginx and PHP are fully equipped to make use of the GeoIP country and the GeoIP city lite database.
You can easily use the defined variables in a script or extension to validate the GeoIP data of the remote address.

Variables defined in Nginx and PHP

Both the city database as well as the country database provide their own constants within PHP and variables in Nginx:

GeoIP Country data

Name	PHP Constant	Nginx Variable
Country Code	GEOIP_COUNTRY_CODE	$geoip_country_code
Country Code 3	GEOIP_COUNTRY_CODE3	$geoip_country_code3
Country Code Name	GEOIP_COUNTRY_NAME	$geoip_country_name

GeoIP City Lite data

Name	PHP Constant	Nginx Variable
City Code	GEOIP_CITY_COUNTRY_CODE	$geoip_city_country_code
City Code 3	GEOIP_CITY_COUNTRY_CODE3	$geoip_city_country_code3
City Country Name	GEOIP_CITY_COUNTRY_NAME	$geoip_city_country_name
City Region	GEOIP_REGION	$geoip_region
City	GEOIP_CITY	$geoip_city
City Postal Code	GEOIP_POSTAL_CODE	$geoip_postal_code
City Continent Code	GEOIP_CITY_CONTINENT_CODE	$geoip_city_continent_code
City Latitude	GEOIP_LATITUDE	$geoip_latitude
City Longitude	GEOIP_LONGITUDE	$geoip_longitude

Testing GeoIP in PHP

To test or see the GeoIP functionality in use, you can use this example script: