Information
An inactive interface is rarely monitored or controlled and may expose a network to an undetected attack on that interface. Unauthorized personnel with access to the communication facility could gain access to a router by connecting to a configured interface that is not in use.
If an interface is no longer used, the configuration must be deleted and the interface disabled. For sub-interfaces, delete sub-interfaces that are on inactive interfaces and delete sub-interfaces that are themselves inactive. If the sub-interface is no longer necessary for authorized communications, it must be deleted.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
Delete inactive sub-interfaces and disable and delete the configuration of any inactive ports on the router.
Deleting the sub-interface:
router(config)#no interface Ethernet8.100
Disabling the interface:
router(config)#interface Ethernet 8-10
router(config-if-Et8-10)#shutdown
Resetting the interface to the default-configuration:
router(config)#default interface Ethernet 8