The network device must use its loopback or OOB management interface address as the source address when originating TFTP or FTP traffic.
Using a loopback address as the source address offers a multitude of uses for security, access, management, and scalability of network devices. It is easier to construct appropriate ingress filters for 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. TFTP and FTP messages sent to management servers should use the loopback address as the source address.
Configure the network device to use a loopback interface address as the source address when originating TFTP or FTP traffic. Example: Router(config)# interface loopback 0 Router(config-if)# ip address x.x.x.x 255.255.255.255 Router(config)# ip ftp source-interface loopback0 Router(config)# ip tftp source-interface loopback0 If an OOB management interface is being used, configure the interface for TFTP or FTP traffic origination. Example: Router(config)# ip ftp source-interface fe0/0 Router(config)# ip tftp source-interface fe0/0
Review the configuration and verify a loopback interface address is used as the source address when originating TFTP or FTP traffic. Router# show run Building configuration... ! ! interface Loopback0 description Loopback interface ip address x.x.x.x 255.255.255.255 no ip directed-broadcast ! ... ip telnet source-interface Loopback0 ip tftp source-interface Loopback0 ip ftp source-interface Loopback0 If the device is managed from an OOB management network, the OOB interface must be used instead. Router# show run Building configuration... ! ... ip tftp source-interface fe0/0 ip ftp source-interface fe0/0
Information Assurance Officer