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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter6 Administering the Swi tc h Controlling Switch Access with TACACS+
A method list describes the sequence and authentication methods to be queried to authenticate a user.
You can designate one or more security protocols to be used for authentication, thus ensuring a backup
system for authentication in case the initial method fails. The software uses the first method listed to
authenticate users; if that method fails to respond, the software selects the next authentication method
in the method list. This process continues until there is successful communication with a listed
authentication method or until all defined methods are exhausted. If authe ntica ti on fai ls at an y poi nt in
this cycle—meaning that the security server or loca l use rnam e dat abas e re spon ds by de nying the u se r
access—the authentication process stops, and no other authentication methods are attempted.
Beginning in privileged EXEC mode, follow these steps to configur e logi n a uthe nti cati on:
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 aaa new-model Enable AAA.
Step3 aaa authentication login {default |
list-name} method1 [method2...]Create a login authentication method list.
•To create a default list that is used when a named list is not specified
in the login authentication command, use the default key word
followed by the methods that are to be used in default situations. The
default method list is automatically applied to all interfaces.
•For list-name, specify a character string to name the list you are
creating.
•For method1..., specify the actual method the authentication
algorithm tries. The additional methods of authentication are used
only if the previous method returns an error, not if it fails.
Select one of these methods:
•line—Use the line password for authentication. You must define a
line password before you can use this authentication method. Use the
password password line configuration command.
•local—Use the local username database for authentication. You must
enter username information into the database. Use the username
password global configuration command.
•tacacs+—Uses TACACS+ authentication. You must configure the
TACACS+ server before you can use this authentication method.
Step4 line [console | tty | vty] line-number
[ending-line-number]Enter line configuration mode, and configure the lines t o which you want
to apply the authentication list.
Step5 login authentication {default |
list-name}Apply the authentication list to a line or set of lines.
•If you specify default, use the default list created with the aaa
authentication login command.
•For list-name, specify the list created with the aaa authentication
login command.
Step6 end Return to privileged EXEC mode.
Step7 show running-config Verify your entries.
Step8 copy running-config startup-config (Optional) Save your entries in the configuration file.