80 CHAPTER 10: MAKING YOUR NETWORK SECURE
What is RADIUS? Remote Authentication Dial-In User Service (RADIUS) is an industry 
standard protocol for carrying authentication, authorization and 
configuration information between a network device and a shared 
authentication server. Transactions between each network device and the 
server are authenticated by the use of a shared secret. Additional security 
is provided by encryption of passwords to prevent interception by a 
network snooper.
RADIUS is defined in the RFCs 2865 and 2866, “Remote Authentication 
Dial-in User Service (RADIUS)” and “RADIUS Accounting”.
Network Login, a method of port-based access control, and Switch 
Management Login, used to control administrative access, both utilize 
the RADIUS protocol.