Home > AAA TACACS+ and RADIUS Tutorial


October 18th, 2018 Go to comments

In this part we will have some configuration of Authentication to help you grasp it.


Suppose we configure AAA as follows.

aaa authentication login NO_AUTH none

line console 0
login authentication NO_AUTH

Which login credentials are required when connecting to the console port in this output?

Answer: The console port is authenticated with NO_AUTH list. But this list does not contain any authentication method (it uses “none”) so no authentication is required when connecting to the console port.


Which login credentials are required when connecting to the VTY port in this output?

Router(config)#aaa authentication login default group radius local line

Answer: We used “default” method list so the authentication is applied to all login connections (even if there is no login authentication command). A group of “RADIUS, local and line” is defined so the device will first contact RADIUS server, then local username and finally line password.

Because we are using the list default in the aaa authentication login command, login authentication is automatically applied for all login connections (such as tty, vty, console and aux).


Which login credentials are required when connecting to the VTY port in this output?

Router(config)# aaa authentication login default tacacs+ enable

Answer: The router first attempts to use the TACACS+ method for authentication, then the enable method. Therefore, the enable password is used to authenticate users if the device cannot contact the TACACS+ server.

Note: All the above configuration only uses the first “A” (Authentication) for demonstration. If you wish to learn about two other “A”s (Authorization and Accounting) please visit the Cisco links below:

+ Authorization: https://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfathor.html
+ Accounting: https://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfacct.html




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