USRobotics NETServer/8 - Manual (Page 271)

RADIUS F-11
CHAP authentication using RADIUS
If the NETServer wishes to use RADIUS to authenticate the
remote device, the user name and the password of the remote
device can be stored in the users file on the RADIUS server.
The user name for the remote device must be the user ID that it
will send during CHAP authentication.
The password must be in clear text in order for the MD5 com-
parison to succeed. Remember, the password during CHAP
authentication is known as a shared secret. The remote device
uses the same password. If the NETServer does not have a user
table entry for the remote device, there must be an entry for the
remote device in the RADIUS users file.