Information
Authenticate management access to the network devices. Typically a central authentication store combined with a fallback mechanism should be implemented to allow emergency access, in case the central authentication servers are not available.
Rationale:
Management access to network devices must be authenticated. The default under AAA (local or network) is to require users to log in using a valid user name and password. This rule applies for both local and network AAA. Fallback mode should also be enabled to allow emergency access to the router or switch in the event that the AAA server was unreachable.
Impact:
If no authentication is implemented, any user with network reachability to the management interface can access network devices and change their configuration.
Solution
Configure central authentication for vty lines as follows:
aaa authentication login default group <servergroup>
Default Value:
By default local authentication is configured:
switch# show run all | i 'aaa authentication login'
aaa authentication login default local
aaa authentication login console local
aaa authentication login default fallback error local
aaa authentication login console fallback error local