Access Authentication Control Commands - Extreme Networks EAS 100-24t Switch CLI Manual

Chapter 9: Security

Access Authentication Control Commands

The TACACS / XTACACS / TACACS+ / RADIUS commands allow secure access to the switch using
the TACACS / XTACACS / TACACS+ / 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 / TACACS+ / RADIUS authentication is enabled on the switch, it will contact a TACACS /
XTACACS / TACACS+ / 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.
TACACS+ (Terminal Access Controller Access Control System plus) — Provides detailed access
●
control for authentication for network devices. TACACS+ is facilitated through authentication
commands via one or more centralized servers. The TACACS+ protocol encrypts all traffic between
the switch and the TACACS+ 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 / TACACS+ / RADIUS security function to work properly, a
TACACS / XTACACS / TACACS+ / RADIUS 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 / TACACS+ / RADIUS server to verify, and the server will respond
with one of three messages:
1 The server verifies the username and password, and the user is granted normal user privileges on
the switch.
2 The server will not accept the username and password and the user is denied access to the switch.
3 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, TACACS+ 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 an order of preference 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 six different authentication techniques per user-defined
method list (TACACS / XTACACS / TACACS+ / RADIUS / local / none) for authentication. These
techniques will be listed in an order of preference, and defined by the user for normal user
authentication on the switch, and may contain up to eight authentication techniques. When a user
254
Extreme Networks EAS 100-24t Switch CLI Manual