xStack Gigabit Layer 3 Switch Command Line Interface Manual
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The Access Authentication Control commands let you secure access to the Switch using the TACACS / XTACACS /
and RADIUS protocols. When a user logs in to the Switch or tries to access the administrator level privilege, he or
she is prompted for a password. If TACACS / XTACACS / / RADIUS authentication is enabled on the Switch, it
will contact a TACACS / XTACACS / / RADIUS server to verify the user. If the user is verified, he or she is
granted access to the Switch.
There are currently three versions of the TACACS security protocol, each a separate entity. The Switch’s software supports the
following versions of TACACS:
•
TACACS (Terminal Access Controller Access Control System) —Provides password checking and authentication,
and notification of user actions for security purposes utilizing via one or more centralized TACACS servers, utilizing the UDP
protocol for packet transmission.
•
Extended TACACS (XTACACS) — An extension of the TACACS protocol with the ability to provide more types of
authentication requests and more types of response codes than TACACS. This protocol also uses UDP to transmit packets.
•
(Terminal Access Controller Access Control System plus) — Provides detailed access control for
authentication for network devices. is facilitated through Authentication commands via one or more centralized
servers. The protocol encrypts all traffic between the Switch and the daemon, using the TCP protocol to
ensure reliable delivery.
The Switch also supports the RADIUS protocol for authentication using the Access Authentication Control commands.
RADIUS or Remote Authentication Dial In User Server also uses a remote server for authentication and can be responsible for
receiving user connection requests, authenticating the user and returning all configuration information necessary for the client to
deliver service through the user. RADIUS may be facilitated on this Switch using the commands listed in this section.
In order for the TACACS / XTACACS / security function to work properly, a TACACS / XTACACS /
server must be configured on a device other than the Switch, called a
server host
and it must include usernames and passwords
for authentication. When the user is prompted by the Switch to enter usernames and passwords for authentication, the Switch
contacts the TACACS / XTACACS / server to verify, and the server will respond with one of three messages:
A) The server verifies the username and password, and the user is granted normal user privileges on the Switch.
B) The server will not accept the username and password and the user is denied access to the Switch.
C) The server doesn’t respond to the verification query. At this point, the Switch receives the timeout from the server and
then moves to the next method of verification configured in the method list.
The switch has four built-in
server groups
, one for each of the TACACS, XTACACS, and RADIUS protocols.
These built-in
server groups
are used to authenticate users trying to access the Switch. The users will set
server hosts
in a
preferable order in the built-in
server
group
and when a user tries to gain access to the Switch, the Switch will ask the first
server host
for authentication. If no authentication is made, the second
server host
in the list will be queried, and so on. The
built-in
server group
can only have hosts that are running the specified protocol. For example, the TACACS
server group
can
only have TACACS
server hosts
.
The administrator for the Switch may set up 6 different authentication techniques per user-defined
method list
(TACACS /
XTACACS / / RADIUS / local / none) for authentication. These techniques will be listed in an order preferable, and
defined by the user for normal user authentication on the Switch, and may contain up to eight authentication techniques. When a
user attempts to access the Switch, the Switch will select the first technique listed for authentication. If the first technique goes
through its
server hosts and
no authentication is returned, the Switch will then go to the next technique listed in the server group
for authentication, until the authentication has been verified or denied, or the list is exhausted.
Please note that user granted access to the Switch will be granted normal user privileges on the Switch. To gain access to admin
level privileges, the user must enter the
enable admin
command and then enter a password, which was previously configured by
the administrator of the Switch.
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