OpenRADIUS is a RADIUS server that allows you to use external data sources for anything - shared secrets, accounts and passwords, profiles, session database, NAS lists, called/calling nr. ACLs, accounting storage, and much more. It has a powerful external module interface that uses pre-spawned subprocesses and pipes for communication, allowing you to implement modules in any language that supports Unix pipe I/O. Its behaviour is fully configurable, using a simple built-in language that gives you full control over the request and reply list. It includes versatile LDAP and SQL modules, a full featured RADIUS client, and a fully functional example configuration for metered pre-paid accounts.