The network device must use its loopback or OOB management interface address as the source address when originating TFTP or FTP traffic.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-14677	NET0902	SV-15353r3_rule	ECSC-1	Low

Description
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.

Description

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.

STIG	Date
Perimeter Router Security Technical Implementation Guide Juniper	2018-11-28

Details

Check Text ( C-12820r4_chk )
Review the configuration and verify a loopback interface address is used as the source address when originating TFTP or FTP traffic. Step 1: Verify that a loopback address has been configured with an IP address. The configuration should look similar to the following: interfaces { lo0 { unit 0 { family inet { address x.x.x.x/32; } } } Step 2: There is no method to override the source address default for TFTP and FTP. Hence, the router must be configured to use the loopback as the default source address for all locally generated traffic. This is accomplished by configuring the default-address-selection statement as shown in the following example: system { default-address-selection; … } } If the device is managed from an OOB management network, the OOB interface must be used instead. Note: Only one loopback interface can be configured on Juniper routers; however, multiple addresses can be defined.

Check Text ( C-12820r4_chk )

Review the configuration and verify a loopback interface address is used as the source address when originating TFTP or FTP traffic.

Step 1: Verify that a loopback address has been configured with an IP address. The configuration should look similar to the following:

interfaces {
lo0 {
unit 0 {
family inet {
address x.x.x.x/32;
}
}
}

Step 2: There is no method to override the source address default for TFTP and FTP. Hence, the router must be configured to use the loopback as the default source address for all locally generated traffic. This is accomplished by configuring the default-address-selection statement as shown in the following example:

system {
default-address-selection;
…
}
}

If the device is managed from an OOB management network, the OOB interface must be used instead.

Note: Only one loopback interface can be configured on Juniper routers; however, multiple addresses can be defined.

Fix Text (F-40481r1_fix)
Configure the network device to use a loopback or OOB management interface address as the source address when originating TFTP or FTP traffic.