The Cisco switch must be configured to have gratuitous ARP disabled on all external interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-220431	CISC-RT-000150	SV-220431r856233_rule		Medium

Description

A gratuitous ARP is an ARP broadcast in which the source and destination MAC addresses are the same. It is used to inform the network about a host IP address. A spoofed gratuitous ARP message can cause network mapping information to be stored incorrectly, causing network malfunction.

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

Details

Check Text (C-22146r508378_chk)

Review the configuration to determine if gratuitous ARP is disabled. The following command should not be found in the switch configuration:

ip gratuitous-arps

Note: With Cisco IOS, gratuitous ARP is enabled and disabled globally.

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

Fix Text (F-22135r508379_fix)

Disable gratuitous ARP as shown in the example below:

SW1(config)#no ip gratuitous-arps