6.9.1 Retrieving Session Data

Radius retrieves the list of sessions currently opened by the user either from the system database (see section System Accounting), or from the SQL database (see section sql Accounting). The system administrator determines which method to use.

By default, system accounting database is used. Its advantages are simplicity and ease of handling. It has, however, a serious deficiency: the information is kept in the local files. If you run several radius servers, each of them has no easy way of knowing about the sessions initiated by other servers.

This problem is easy to solve if you run SQL accounting (see section sql Accounting). In this case, each radius server stores the data in your SQL database and can easily retrieve them from there.

To enable use of SQL database for multiple login checking, do the following:

In your ‘raddb/config’ file set:

mlc {
    method sql;
};

In your ‘raddb/sqlserver’ file, specify the queries for retrieving the information about open sessions and, optionally, a query to close an existing open record.

There are two queries for retrieving the information: mlc_user_query returns the list of sessions opened by the user, mlc_realm_query returns the list of sessions opened for the given realm. Each of them should return a list of 4-element tuples(4):

user-name, nas-ip-address, nas-port-id, acct-session-id

Here is an example of mlc_user_query and mlc_realm_query:

mlc_user_query SELECT user_name,nas_ip_address,\
                      nas_port_id,acct_session_id \
               FROM calls \
               WHERE user_name='%C{User-Name}' \
               AND status = 1

mlc_realm_query SELECT user_name,nas_ip_address,\
                       nas_port_id,acct_session_id \
                FROM calls \
                WHERE realm_name='%C{Realm-Name}'     

Apart from these two queries you may also wish to provide a query for closing a hung record. By default, radiusd will use acct_stop_query. If you wish to override it, supply a query named mlc_stop_query, for example:

mlc_stop_query UPDATE calls \
               SET status=4,\
                acct_session_time=unix_timestamp(now())-\
                                  unix_timestamp(event_date_time) \
               WHERE user_name='%C{User-Name}' \
                 AND status = 1 \
                 AND acct_session_id='%C{Acct-Session-Id}' 

See section Writing SQL Accounting Query Templates, for detailed information on how to write these queries.

This document was generated by Sergey Poznyakoff on December, 6 2008 using texi2html 1.78.