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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-216675	CISC-RT-000370	SV-216675r531086_rule		Low

Description
CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP 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 CDP 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

CDP is a Cisco proprietary neighbor discovery protocol used to advertise device capabilities, configuration information, and device identity. CDP 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 CDP 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 XE Router RTR Security Technical Implementation Guide	2021-03-26

Details

Check Text ( C-17908r287976_chk )
This requirement is not applicable for the DODIN Backbone. Step 1: Verify if CDP is enabled globally as shown below: cdp run By default, CDP is not enabled globally or on any interface. If CDP is enabled globally, proceed to step 2. Step 2: Verify CDP is not enabled on any external interface as shown in the example below: interface GigabitEthernet2 ip address z.1.24.4 255.255.255.252 … … … cdp enable If CDP is enabled on any external interface, this is a finding.

Check Text ( C-17908r287976_chk )

This requirement is not applicable for the DODIN Backbone.

Step 1: Verify if CDP is enabled globally as shown below:

cdp run

By default, CDP is not enabled globally or on any interface. If CDP is enabled globally, proceed to step 2.

Step 2: Verify CDP is not enabled on any external interface as shown in the example below:

interface GigabitEthernet2
ip address z.1.24.4 255.255.255.252
…
…
…
cdp enable

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

Fix Text (F-17906r287977_fix)
This requirement is not applicable for the DODIN Backbone. Disable CDP on all external interfaces via no cdp enable command or disable CDP globally via no cdp run command.