The router must use its loopback or OOB management interface address as the source address when originating NetFlow traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-14676	NET0901	SV-15349r2_rule		Low

Description
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. Netflow messages sent to management servers should use the loopback address as the source address.

Description

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. Netflow messages sent to management servers should use the loopback address as the source address.

STIG	Date
Infrastructure Router Security Technical Implementation Guide Cisco	2018-03-06

Details

Check Text ( C-12815r2_chk )
Review the configuration and verify the loopback interface address is used as the source address when originating NetFlow traffic. If the device is managed from an OOB management network, the OOB interface must be used instead. The configuration should look similar as shown in the following example: interface loopback 0 ip address 10.10.2.1 255.255.255.255 … … ip flow-sampling-mode packet-interval 100 ip flow-export destination 192.168.3.33 9991 ip flow-export source Loopback0 Note: IOS allows multiple loopback interfaces to be defined.

Check Text ( C-12815r2_chk )

Review the configuration and verify the loopback interface address is used as the source address when originating NetFlow traffic. If the device is managed from an OOB management network, the OOB interface must be used instead. The configuration should look similar as shown in the following example:
interface loopback 0
ip address 10.10.2.1 255.255.255.255
…
…
ip flow-sampling-mode packet-interval 100
ip flow-export destination 192.168.3.33 9991
ip flow-export source Loopback0

Note: IOS allows multiple loopback interfaces to be defined.

Fix Text (F-14138r2_fix)
Configure the router to use its loopback or OOB management interface address as the source address when originating NetFlow traffic.