IronPort Systems 4108GL - Manual (Page 180)

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Using Passwords and TACACS+ To Protect Against Unauthorized Access
TACACS+ Authentication for Central Control of Switch Access Security
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For local authentication, the switch uses the operator-level and manager-level
username/password set(s) previously configured locally on the switch. (These
are the usernames and passwords you can configure using the CLI password
command, the web browser interface, or the menu interface—which enables
only local password configuration).
■ If the operator at the requesting terminal correctly enters the user-
name/password pair for either access level, access is granted.
■ If the username/password pair entered at the requesting terminal does
not match either username/password pair previously configured
locally in the switch, access is denied. In this case, the terminal is
again prompted to enter a username/password pair. In the default
configuration, the switch allows up to three attempts. If the requesting
terminal exhausts the attempt limit without a successful authentica-
tion, the login session is terminated and the operator at the requesting
terminal must initiate a new session before trying again.
Note The switch’s menu allows you to configure only the local Operator and
Manager passwords, and not any usernames. In this case, all prompts for local
authentication will request only a local password. However, if you use the CLI
or the web browser interface to configure usernames for local access, you will
see a prompt for both a local username and a local password during local
authentication.
Using the Encryption Key
General Operation
When used, the encryption key (sometimes termed "key", "secret key", or
"secret") helps to prevent unauthorized intruders on the network from reading
username and password information in TACACS+ packets moving between
the switch and a TACACS+ server. At the TACACS+ server, a key may include
both of the following:
■ Global key: A general key assignment in the TACACS+ server appli-
cation that applies to all TACACS-aware devices for which an indi-
vidual key has not been configured.
■ Server-Specific key: A unique key assignment in the TACACS+
server application that applies to a specific TACACS-aware device.