Including and configuring a module

Some modules can only be used for a specific function. The pap module is like that and used solely for authentication. The sql module in contrast can be used for authorization, session checking, as well as accounting. It all depends on what functionality the author of the module has included.

The sql module (rlm_sql.so) makes use of sub-modules. This creates an abstraction layer. Depending on how the main sql module is configured, it will make use of a specific sub-module to interact with a certain type of database. Sub-modules are available to connect to MySQL (rml_sql_mysql.so), PostgreSQL (rlm_sql_postgresql.so), Microsoft SQL Server (rlm_sql_iodbc.so), and Oracle (rlm_sql_oracle.so) databases.

The sql sub-modules in turn can also be configured to fine-tune their behavior.