KTI KGS-3120, Руководство по эксплуатации, Страница: 163 / 221

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To set the SSH User Authentication parameters on the Switch, a user account must be
previously configured. For more information on configuring local user accounts on the
Switch, see the Security IP section of this document.
Access Authentication Control
The TACACS/XTACACS//RADIUS commands let you secure access to the switch using
the TACACS/XTACACS//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
In order for the TACACS/XTACACS//RADIUS security function to work properly, a
TACACS/XTACACS//RADIUS server must be configured on a device other than the
switch, called an Authentication Server Host and it must include usernames and passwords for authen-
tication. When the user is prompted by the switch to enter usernames and passwords for authentica-
tion, the switch contacts the TACACS/XTACACS//RADIUS server to verify, and the
server will respond with one of three messages:
• The server verifies the username and password, and the user is granted normal user privileges on
the switch.
• The server will not accept the username and password and the user is denied access to the
switch.
• 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 Authentication Server Groups, one for each of the TACACS, XTACACS,
, and RADIUS protocols. These built-in Authentication Server Groups are used to authen-
ticate users trying to access the switch. The users will set Authentication Server Hosts in a preferable
order in the built-in Authentication Server Groups and when a user tries to gain access to the switch,
the switch will ask the first Authentication Server Hosts for authentication. If no authentication is
made, the second server host in the list will be queried, and so on. The built-in Authentication Server
Groups can only have hosts that are running the specified protocol. For example, the TACACS Au-