The router must use its loopback or OOB management interface address as the source address when originating TACACS+ or RADIUS traffic.
Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of routers. It is easier to construct appropriate ingress filters for router management plane traffic destined to the network management subnet since the source addresses will be from the range used for loopback interfaces instead of a larger range of addresses used for physical interfaces. Log information recorded by authentication and syslog servers will record the router’s loopback address instead of the numerous physical interface addresses. TACACS+, RADIUS messages sent to management servers should use the loopback address as the source address.
Configure the device to use its loopback or OOB management interface address as the source address when originating authentication services traffic.
Review the configuration and verify the loopback interface address is used as the source address when originating TACACS+ or RADIUS traffic. If the device is managed from an OOB management network, the OOB interface must be used instead. Verify that a loopback address has been configured as shown in the following example: interface loopback 0 ip address 10.10.2.1 255.255.255.255 … ip tacacs source-interface Loopback0 ip radius source-interface Loopback0 Note: IOS allows multiple loopback interfaces to be defined.
Information Assurance Officer