ZyXEL Communications NBG-417N, User Manual, Page: 256 / 279

Appendix E Wireless LANs
User
’
s Guide
257
Types of RADIUS Messages
The following types of RADIUS messages are exchanged between the access point
and the RADIUS server for user authentication:
• Access-Request
Sent by an access point requesting authentication.
• Access-Reject
Sent by a RADIUS server rejecting access.
• Access-Accept
Sent by a RADIUS server allowing access.
• Access-Challenge
Sent by a RADIUS server requesting more information in order to allow access.
The access point sends a proper response from the user and then sends another
Access-Request message.
The following types of RADIUS messages are exchanged between the access point
and the RADIUS server for user accounting:
• Accounting-Request
Sent by the access point requesting accounting.
• Accounting-Response
Sent by the RADIUS server to indicate that it has started or stopped accounting.
In order to ensure network security, the access point and the RADIUS server use a
shared secret key, which is a password, they both know. The key is not sent over
the network. In addition to the shared key, password information exchanged is
also encrypted to protect the network from unauthorized access.
Types of Authentication
This appendix discusses some popular authentication types: EAP-MD5 , EAP-TLS ,
EAP-TTLS , PEAP and LEAP .
The type of authentication you use depends on the RADIUS server or the AP.
Consult your network administrator for more information.
EAP-MD5 (Message-Digest Algorithm 5)
MD5 authentication is the simplest one-way authentication method. The
authentication server sends a challenge to the wireless station. The wireless
station
‘ proves ’ that it knows the password by encrypting the password with the
challenge and sends back the information. Password is not sent in plain text.
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