The router must be configured to have Gratuitous ARP disabled on all external interfaces.
Overview
Finding ID
Version
Rule ID
IA Controls
Severity
V-207151
SRG-NET-000362-RTR-000111
SV-207151r856635_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.