← Back to Cisco IOS XR Router RTR Security Technical Implementation Guide

V-216764

CAT III (Low)

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

Rule ID

SV-216764r856442_rule

STIG

Cisco IOS XR Router RTR Security Technical Implementation Guide

Version

V3R3

CCIs

CCI-002403

Discussion

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.

Check Content

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

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