The Cisco perimeter router must be configured to have Link Layer Discovery Protocol (LLDP) disabled on all external interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-216764	CISC-RT-000360	SV-216764r856442_rule		Low

Description
LLDP is a neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. LLDP is media- and protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing LLDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack.

Description

LLDP is a neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. LLDP is media- and protocol-independent as it runs over layer 2; therefore, two network nodes that support different layer 3 protocols can still learn about each other. Allowing LLDP messages to reach external network nodes provides an attacker a method to obtain information of the network infrastructure that can be useful to plan an attack.

STIG	Date
Cisco IOS XR Router RTR Security Technical Implementation Guide	2024-06-06

Details

Check Text ( C-17996r288675_chk )
This requirement is not applicable for the DODIN Backbone. Step 1: Verify LLDP is not enabled globally via the command lldp By default LLDP is not enabled globally. If LLDP is enabled, proceed to step 2. Step 2: Verify LLDP transmit is disabled on any external interface as shown in the example below. interface GigabitEthernet0/0/0/1 ipv4 address x.1.34.3 255.255.255.252 lldp transmit disable Note: LLDP is enabled by default on all interfaces once it is enabled globally; hence the commands lldp transmit and lldp receive will not be visible on the interface configuration. If LLDP transmit is enabled on any external interface, this is a finding.

Check Text ( C-17996r288675_chk )

This requirement is not applicable for the DODIN Backbone.

Step 1: Verify LLDP is not enabled globally via the command

lldp

By default LLDP is not enabled globally. If LLDP is enabled, proceed to step 2.

Step 2: Verify LLDP transmit is disabled on any external interface as shown in the example below.

interface GigabitEthernet0/0/0/1
ipv4 address x.1.34.3 255.255.255.252
lldp
transmit disable

Note: LLDP is enabled by default on all interfaces once it is enabled globally; hence the commands lldp transmit and lldp receive will not be visible on the interface configuration.

If LLDP transmit is enabled on any external interface, this is a finding.

Fix Text (F-17994r288676_fix)
Disable LLDP transmit on all external interfaces as shown in the example below. RP/0/0/CPU0:R3(config)#interface g0/0/0/1 RP/0/0/CPU0:R3(config-if)#lldp transmit disable