Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.112.0P1 - Page 782

If authentication fails using the primary method, Dell Networking OS employs the second method (or third method, if necessary) automatically. For example, if the TACACS+ server is reachable, but the server key is invalid, Dell Networking OS proceeds to the next authentication method. In the following example, the TACACS+ is incorrect, but the user is still authenticated by the secondary method. First bold line: Server key purposely changed to incorrect value. Second bold line: User authenticated using the secondary method. Dell(conf)# Dell(conf)#do show run aaa ! aaa authentication enable default tacacs+ enable aaa authentication enable LOCAL enable tacacs+ aaa authentication login default tacacs+ local aaa authentication login LOCAL local tacacs+ aaa authorization exec default tacacs+ none aaa authorization commands 1 default tacacs+ none aaa authorization commands 15 default tacacs+ none aaa accounting exec default start-stop tacacs+ aaa accounting commands 1 default start-stop tacacs+ aaa accounting commands 15 default start-stop tacacs+ Dell(conf)# Dell(conf)#do show run tacacs+ ! tacacs-server key 7 d05206c308f4d35b tacacs-server host 10.10.10.10 timeout 1 Dell(conf)#tacacs-server key angeline Dell(conf)#%RPM0-P:CP %SEC-5-LOGIN_SUCCESS: Login successful for user admin on vty0 (10.11.9.209) %RPM0-P:CP %SEC-3-AUTHENTICATION_ENABLE_SUCCESS: Enable password authentication success on vty0 ( 10.11.9.209 ) %RPM0-P:CP %SEC-5-LOGOUT: Exec session is terminated for user admin on line vty0 (10.11.9.209) Dell(conf)#username angeline password angeline Dell(conf)#%RPM0-P:CP %SEC-5-LOGIN_SUCCESS: Login successful for user angeline on vty0 (10.11.9.209) %RPM0-P:CP %SEC-3-AUTHENTICATION_ENABLE_SUCCESS: Enable password authentication success on vty0 ( 10.11.9.209 ) Monitoring TACACS+ To view information on TACACS+ transactions, use the following command. • View TACACS+ transactions to troubleshoot problems. EXEC Privilege mode debug tacacs+ TACACS+ Remote Authentication The system takes the access class from the TACACS+ server. Access class is the class of service that restricts Telnet access and packet sizes. If you have configured remote authorization, the system ignores the access class you have configured for the VTY line and gets this access class information from the TACACS+ server. The system must know the username and password of the incoming user before it can fetch the access class from the server. A user, therefore, at least sees the login prompt. If the access class denies the connection, the system closes the Telnet session immediately. The following example demonstrates how to configure the access-class from a TACACS+ server. This configuration ignores the configured access-class on the VTY line. If you have configured a deny10 ACL on the TACACS+ server, the system downloads it and applies it. If the user is found to be coming from the 10.0.0.0 subnet, the system also immediately closes the Telnet connection. Note, that no matter where the user is coming from, they see the login prompt. 782 Security