Addendum

First bold line: Server key purposely changed to incorrect value.
Second bold line: User authenticated using the secondary method.
Example of a Failed Authentication
FTOS(conf)#
FTOS(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+
FTOS(conf)#
FTOS(conf)#do show run tacacs+
!
tacacs-server key 7 d05206c308f4d35b
tacacs-server host 10.10.10.10 timeout 1
FTOS(conf)#
tacacs-server key angeline
FTOS(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)
FTOS(conf)#username angeline password angeline
FTOS(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 and Authorization
FTOS 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, FTOS ignores the access class you have configured for the
VTY line. FTOS instead gets this access class information from the TACACS+ server. FTOS 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, FTOS 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, FTOS downloads it and applies it. If the user is found to be coming from the
10.0.0.0 subnet, FTOS also immediately closes the Telnet connection. Note, that no matter where the
user is coming from, they see the login prompt.
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Security for M I/O Aggregator