# &adminguide;

## Overview

This module contains all authentication related functions that need the access to the database. This module should be used together with auth module, it cannot be used independently because it depends on the module. Select this module if you want to use database to store authentication information like subscriber usernames and passwords. If you want to use radius authentication, then use auth_radius instead.

## Dependencies

### &kamailio; Modules

The module depends on the following modules (in other words the listed modules must be loaded before this module):

- auth -- Generic authentication functions

- database -- Any database module (currently mysql, postgres, dbtext)

### External Libraries or Applications

The following libraries or applications must be installed before running &kamailio; with this module loaded:

- none

## Parameters

### `db_url` (string)

This is URL of the database to be used. Value of the parameter depends on the database module used. For example for mysql and postgres modules this is something like mysql://username:password@host:port/database. For dbtext module (which stores data in plaintext files) it is directory in which the database resides.

Default value is &defaultrodb;.

#### `db_url` parameter usage

    ...
    modparam("auth_db", "db_url", "&exampledb;")
    ...

### `user_column` (string)

This is the name of the column holding usernames. Default value is fine for most people. Use the parameter if you really need to change it.

Default value is username.

#### `user_column` parameter usage

    ...
    modparam("auth_db", "user_column", "user")
    ...

### `domain_column` (string)

This is the name of the column holding domains of users. Default value is fine for most people. Use the parameter if you really need to change it.

Default value is domain.

#### `domain_column` parameter usage

    ...
    modparam("auth_db", "domain_column", "domain")
    ...

### `password_column` (string)

This is the name of the column holding passwords. Passwords can be either stored as plain text or pre-calculated HA1 strings. HA1 strings are MD5 hashes of username, password, and realm. HA1 strings are more safe because the server doesn't need to know plaintext passwords and they cannot be obtained from HA1 strings.

Default value is ha1.

#### `password_column` parameter usage

    ...
    modparam("auth_db", "password_column", "password")
    ...

### `password_column_2` (string)

As described in the previous section this parameter contains name of column holding pre-calculated HA1 string that were calculated including the domain in the username. This parameter is used only when `calculate_ha1` is set to 0 and user agent send a credentials containing the domain in the username.

Default value of the parameter is ha1b.

#### `password_column_2` parameter usage

    ...
    modparam("auth_db", "password_column_2", "ha1_2")
    ...

### `calculate_ha1` (integer)

This parameter tells the server whether it should use a pre-calculated HA1 string or plaintext passwords for authentication.

If the parameter is set to 0 and the username parameter of credentials contains also @domain (some user agents append the domain to the username parameter), then the server will use the HA1 values from the column specified in the password_column_2 parameter. If the username parameter doesn't contain a domain, the server will use the HA1 values from the column given in the password_columnparameter.

If the parameter is set to 1 then the HA1 value will be calculated from the column specified in the password_column parameter.

The password_column_2column contain also HA1 strings but they should be calculated including the domain in the username parameter (as opposed to password_column which (when containing HA1 strings) should always contains HA1 strings calculated without domain in username.

This ensures that the authentication will always work when using pre-calculated HA1 strings, not depending on the presence of the domain in username.

Default value of this parameter is 0.

#### `calculate_ha1` parameter usage

    ...
    modparam("auth_db", "calculate_ha1", 1)
    ...

### `use_domain` (integer)

If true (not 0), domain will be also used when looking up in the subscriber table. If you have a multi-domain setup, it is strongly recommended to turn on this parameter to avoid username overlapping between domains.

IMPORTANT: before turning on this parameter, be sure that the `domain` column in `subscriber` table is properly populated.

Default value is 0 (false).

#### `use_domain` parameter usage

    ...
    modparam("auth_db", "use_domain", 1)
    ...

### `load_credentials` (string)

This parameter specifies of credentials to be fetch from database when the authentication is performed. The loaded credentials will be stored in AVPs. If the AVP name is not specifically given, it will be used a NAME AVP with the same name as the column name.

Parameter syntax:

- load_credentials = credential (';' credential)*

- credential = (avp_specification '=' column_name) | (column_name)

- avp_specification = '$avp(' + 'i:'ID | 's:'NAME | alias + ')'

Default value of this parameter is NULL (no credentials loaded).

#### `load_credentials` parameter usage

    ...
    # load rpid column into $avp(i:123) and email_address column
    # into $avp(s:email_address)
    modparam("auth_db", "load_credentials", "$avp(i:123)=rpid;email_address")
    ...

### `version_table` (integer)

If set to 0, the module will skip checking the version for subscriber table.

Default value is 1 (check for table version).

#### `version_table` parameter usage

    ...
    modparam("auth_db", "version_table", 0)
    ...

### `force_generate_avps` (integer)

If set to different than 0, the module will fetch user DB attributes even if authentication failed.

Default value is 0 (don't fetch user DB attributes if authentication failed).

#### `force_generate_avps` parameter usage

    ...
    modparam("auth_db", "force_generate_avps", 1)
    ...

## Functions

### `www_authenticate(realm, table [, method])`

Name alias: www_authorize(realm, table)

The function verifies credentials according to RFC2617. If the credentials are verified successfully then the function will succeed and mark the credentials as authorized (marked credentials can be later used by some other functions). If the function was unable to verify the credentials for some reason then it will fail and the script should call `www_challenge` which will challenge the user again.

Negative codes may be interpreted as follows:

- -1 (generic error) - Bad credentials , couldn't parse credentials , no memory left , couldn't fetch from table , couldn't get realm or some generic error occurred and no reply was sent out;

- -2 (invalid password) - wrong password;

- -3 (invalid user) - authentication user does not exist.

- -4 (nonce expired) - the nonce has expired

- -5 (no credentials) - request does not contain an Authorization header with the correct realm.

- -6 (nonce reused) - the nonce has already been used to authenticate a previous request

- -8 (authuser mismatch) - depending on the method, the From/To/RURI user does not match the authentication user (see auth_check() function).

Meaning of the parameters is as follows:

- realm - Realm is an opaque string that the user agent should present to the user so he can decide what username and password to use. Usually this is domain of the host the server is running on.

  It must not be empty string . In case of REGISTER requests To header field domain (e.g., variable $td) can be used (because this header field represents the user being registered), for all other messages From header field domain can be used (e.g., variable $fd).

  The string may contain pseudo variables.

- table - Table to be used to lookup usernames and passwords (usually subscribers table).

- method - the method to be used for authentication. This parameter is optional and if not set is the first "word" on the request-line.

This function can be used from REQUEST_ROUTE.

#### `www_authorize` usage

    ...
    if (!www_authorize("kamailio.org", "subscriber")) {
    	www_challenge("kamailio.org", "1");
    };
    ...

### `www_authorize(realm, table)`

It is same function as www_authenticate(realm, table). This name is kept for backward compatibility, since it was named this way first time by it actually does user authentication.

### `proxy_authenticate(realm, table)`

Name alias: proxy_authorize(realm, table)

The function verifies credentials according to RFC2617. If the credentials are verified successfully then the function will succeed and mark the credentials as authorized (marked credentials can be later used by some other functions). If the function was unable to verify the credentials for some reason then it will fail and the script should call `proxy_challenge` which will challenge the user again.

Negative return codes have the same meaning as for www_authenticate().

Meaning of the parameters is as follows:

- realm - Realm is an opaque string that the user agent should present to the user so he can decide what username and password to use. Usually this is domain of the host the server is running on.

  It must not be empty string . Apart of a static string, typical value is From header field domain (e.g., variable $fd).

  If an empty string is used then the server will generate it from the request. From header field domain will be used as realm.

  The string may contain pseudo variables.

- table - Table to be used to lookup usernames and passwords (usually subscribers table).

This function can be used from REQUEST_ROUTE.

#### proxy_authorize usage

    ...
    if (!proxy_authorize("$fd", "subscriber)) {
    	proxy_challenge("$fd", "1");  # Realm will be autogenerated
    };
    ...

### `proxy_authorize(realm, table)`

It is same function as proxy_authenticate(realm, table). This name is kept for backward compatibility, since it was named this way first time but it actually does user authentication.

### `auth_check(realm, table, flags)`

The function combines the functionalities of `www_authenticate` and `proxy_authenticate`, first being executed if the SIP request is a REGISTER, the second for the rest.

In addition, a matter of flags parameter value, the function checks if authentication username matches From/To header username, and Request-URI in case of PUBLISH.

Negative return codes have the same meaning as for www_authenticate().

Meaning of the parameters is as follows:

- realm - Realm is an opaque string that the user agent should present to the user so he can decide what username and password to use. Usually this is domain of the host the server is running on.

  It must not be empty string . Apart of a static string, typical value is From header field domain (e.g., variable $fd).

  The string may contain pseudo variables.

- table - Table to be used to lookup usernames and passwords (usually subscribers table).

  The string may contain pseudo variables.

- flags - set of flags to control the behaviour of the function. If it is 1, then the function will check to see if the authentication username matches either To or From header username. REGISTER requests: From and To must match the authentication user. PUBLISH requests: From, To and Request-URI must match the authentication user. All other requests: From header must match the authentication user. If bit 2 is set as well (flags==3), the ID check is skipped for INVITE, BYE, PRACK, UPDATE, MESSAGE - these requests can come with anonymous caller id. If set to 0, then all user checks are skipped.

  Additionally all domains in the checked URIs and the realm in the authentication header will be checked to match the provided realm parameter.

  The string may contain pseudo variables.

This function can be used from REQUEST_ROUTE.

#### auth_check usage

    ...
    if (!auth_check("$fd", "subscriber", "1")) {
        auth_challenge("$fd", "1");
        exit;
    }
    ...

### `is_subscriber(uri, dbtable, flags)`

The function checks if there is a subscriber corresponding to the AoR in uri parameter. It uses same database connection as for authentication functions.

In addition, if the subscriber record is found, then the load_credentials attributes are loaded. A use case can be loading the credential attributes for callee.

Meaning of the parameters is as follows:

- uri - a valid SIP URI value to identify the subscriber. The string may contain pseudo variables.

- dbtable - Table to be used to lookup username and domain from URI (usually subscriber table). The string may contain pseudo variables.

- flags - set of flags to control the behaviour of the function. If 1st bit is set, then the function will use the domain part of the URI to perform the database table search. If 2nd bit is set, then the credentials are not loaded in variables (a simple check if subscriber exists).

  The parameter may be a pseudo variable.

This function can be used from ANY_ROUTE.

#### is_subscriber usage

    ...
    if (!is_subscriber("$ru", "subscriber", "3")) {
        # callee is not a local subscriber
        ...
    }
    ...