Reference Guide

RADIUS
Remote authentication dial-in user service (RADIUS) is a distributed client/server protocol.
This protocol transmits authentication, authorization, and configuration information between a central RADIUS server and a
RADIUS client (the Dell Networking system). The system sends user information to the RADIUS server and requests
authentication of the user and password. The RADIUS server returns one of the following responses:
● Access-Accept — the RADIUS server authenticates the user.
● Access-Reject — the RADIUS server does not authenticate the user.
If an error occurs in the transmission or reception of RADIUS packets, you can view the error by enabling the debug radius
command.
Transactions between the RADIUS server and the client are encrypted (the users’ passwords are not sent in plain text). RADIUS
uses UDP as the transport protocol between the RADIUS server host and the client.
For more information about RADIUS, refer to RFC 2865, Remote Authentication Dial-in User Service.
RADIUS Authentication and Authorization
The system supports RADIUS for user authentication (text password) at login and can be specified as one of the login
authentication methods in the aaa authentication login command.
When configuring AAA authorization, you can configure to limit the attributes of services available to a user. When you enable
authorization, the network access server uses configuration information from the user profile to issue the user's session. The
user’s access is limited based on the configuration attributes.
RADIUS exec-authorization stores a user-shell profile and that is applied during user login. You may name the relevant named-
lists with either a unique name or the default name. When you enable authorization by the RADIUS server, the server returns the
following information to the client:
● Idle Time
● ACL Configuration Information
● Auto-Command
● Privilege Levels
After gaining authorization for the first time, you may configure these attributes.
NOTE:
RADIUS authentication/authorization is done for every login. There is no difference between first-time login and
subsequent logins.
Idle Time
Every session line has its own idle-time. If the idle-time value is not changed, the default value of 30 minutes is used.
RADIUS specifies idle-time allow for a user during a session before timeout. When a user logs in, the lower of the two idle-time
values (configured or default) is used. The idle-time value is updated if both of the following happens:
● The administrator changes the idle-time of the line on which the user has logged in.
● The idle-time is lower than the RADIUS-returned idle-time.
ACL Configuration Information
The RADIUS server can specify an ACL. If an ACL is configured on the RADIUS server, and if that ACL is present, the user may
be allowed access based on that ACL.
If the ACL is absent, authorization fails, and a message is logged indicating this.
RADIUS can specify an ACL for the user if both of the following are true:
● If an ACL is absent.
● If there is a very long delay for an entry, or a denied entry because of an ACL, and a message is logged.
NOTE:
The ACL name must be a string. Only standard ACLs in authorization (both RADIUS and TACACS) are supported.
Authorization is denied in cases using Extended ACLs.
670 Security