The ngx_http_geo_module module creates variables whose values depend on the client IP address.

geo $geo {
    default        0;

    127.0.0.1      2;
    192.168.1.0/24 1;
    10.1.0.0/16    1;

    ::1            2;
    2001:0db8::/32 1;
}

Describes the dependency of values of the specified variable on the client IP address. By default an address is taken from the $remote_addr variable but it can also be taken from another variable (0.7.27), for example:

geo $arg_remote_addr $geo {
    ...;
}

Since variables are evaluated only when used, the mere existence of even a large number of declared “geo” variables does not incur any extra costs for request processing.

If the value of a variable does not represent a valid IP address then the “255.255.255.255” address is used.

Addresses are specified either as prefixes in CIDR notation (including individual addresses) or as ranges (0.7.23).

IPv6 prefixes are supported starting from version 1.3.10.

The following special parameters are also supported:

delete

deletes the specified network (0.7.23).

default

a value of variable if the client address does not match any of the specified addresses. When addresses are specified in CIDR notation, “0.0.0.0/0” and “::/0” can be used instead of default. When default is not specified, the default value will be an empty string.

include

includes a file with addresses and values. There can be several inclusions.

proxy

defines trusted addresses (0.8.7, 0.7.63). When a request comes from a trusted address, an address from the “X-Forwarded-For” request header field will be used instead. In contrast to the regular addresses, trusted addresses are checked sequentially.

Trusted IPv6 addresses are supported starting from versions 1.3.0 and 1.2.1.

proxy_recursive

enables recursive address search (1.3.0, 1.2.1). If recursive search is disabled then instead of an original client address that matches one of the trusted addresses, the last address sent in “X-Forwarded-For” will be used. If recursive search is enabled then instead an original client address that matches one of the trusted addresses, the last non-trusted address sent in “X-Forwarded-For” will be used.

ranges

indicates that addresses are specified as ranges (0.7.23). This parameter should be the first. To speed up loading of a geo base, addresses should be put in increasing order.

Example:

geo $country {
    default        ZZ;
    include        conf/geo.conf;
    delete         127.0.0.0/16;
    proxy          192.168.100.0/24;
    proxy          2001:0db8::/32;

    127.0.0.0/24   US;
    127.0.0.1/32   RU;
    10.1.0.0/16    RU;
    192.168.1.0/24 UK;
}

The conf/geo.conf file could contain the following lines:

10.2.0.0/16    RU;
192.168.2.0/24 RU;

A value of the most specific match is used. For example, for the 127.0.0.1 address the value “RU” will be chosen, not “US”.

Example with ranges:

geo $country {
    ranges;
    default                   ZZ;
    127.0.0.0-127.0.0.0       US;
    127.0.0.1-127.0.0.1       RU;
    127.0.0.1-127.0.0.255     US;
    10.1.0.0-10.1.255.255     RU;
    192.168.1.0-192.168.1.255 UK;
}