Chapter 3 Authentication for FortiOS 5.0 : Authentication servers : RADIUS servers : Microsoft RADIUS servers : Microsoft RADIUS servers
  
Microsoft RADIUS servers
Microsoft Windows Server 2000, 2003, and 2008 have RADIUS support built-in. Microsoft specific RADIUS features are defined in RFC 2548. The Microsoft RADIUS implementation can use Active Directory for user credentials.
For details on Microsoft RADIUS server configurations, refer to Microsoft documentation.