The ngx_http_userid_module module sets cookies suitable for client identification. Received and set cookies can be logged using the embedded variables $uid_got and $uid_set. This module is compatible with the mod_uid module for Apache.

userid         on;
userid_name    uid;
userid_domain  example.com;
userid_path    /;
userid_expires 365d;
userid_p3p     'policyref="/w3c/p3p.xml", CP="CUR ADM OUR NOR STA NID"';

userid off;

Allows or prohibits to set cookies and log the received cookies:

on

allows to set version 2 cookies and log the received cookies;

v1

allows to set version 1 cookies and log the received cookies;

log

prohibits to set cookies but allows to log the received cookies;

off

prohibits to set cookies and log the received cookies.

userid_domain none;

Defines a domain for which the cookie is set. The parameter none disables setting a domain for a cookie.

userid_expires off;

Sets a time during which a browser should keep the cookie. The parameter max will cause the cookie to expire on “31 Dec 2037 23:55:55 GMT”. This is the maximum time understood by old browsers. The parameter off will cause the cookie to expire at the end of a browser session.

userid_mark off;

If parameter is not off, enables the cookie marking mechanism and sets a character used as a mark. This mechanism allows to add or change userid_p3p and/or cookie expiration time while preserving the client identifier. The mark can be any letter of the English alphabet (case-sensitive), digit, or the “=” character.

If a mark is set, it is compared with the first padding symbol in the base64 representation of client identifier passed in a cookie. If they do not match, a cookie is resent with the specified mark, expiration time and a “P3P” header.

userid_name uid;

Sets a cookie name.

userid_p3p none;

Sets a value for the “P3P” header field that will be sent along with a cookie. If set to the special value none, the “P3P” header will not be sent in a response.

userid_path /;

Defines a path for which the cookie is set.

userid_service IP address of the server;

If identifiers are issued by multiple servers (services), each service should be assigned its own number in order to ensure that client identifiers are unique. For version 1 cookies the default value is zero. For version 2 cookies this is the number composed from the last four octets of the server’s IP address.

The ngx_http_userid_module module supports the following embedded variables:

$uid_got

The cookie name and received client identifier.

$uid_reset

If set to a non-empty string, and it is not “0”, client identifiers are reset. The special value “log” additionally leads to the output of messages about reset identifiers to the error_log.

$uid_set

The cookie name and sent client identifier.