RADIUS: Basics Process Description
If the user name and password are correct, the server sends an Authentication Acknowledgment that includes information on the user's network system and service requirements. For example, the RADIUS server will tell the NAS that a user needs TCP/IP and/or NetWare using PPP (Point-to-Point Protocol) or that the user needs SLIP (Serial Line Internet Protocol) to connect to the network. The acknowledgment can even contain filtering information to limit a user's access to specific resources on the network.