Microsoft Internet Security and Acceleration (ISA) Server 2004 Administrators Pocket Consultant (Pro-Administrators Pocket Consultant)

RADIUS support in ISA Server 2004: http://support.microsoft.com/default.aspx?scid=kb;en-us;886994

The RADIUS authentication process in ISA Server 2004: http://support.microsoft.com/default.aspx?scid=kb;en-us;884492