The Cisco router must be configured to have Gratuitous ARP disabled on all external interfaces.
An XCCDF Rule
Description
<VulnDiscussion>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.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-216653r855814_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Disable gratuitous ARP as shown in the example below:
R5(config)#no ip gratuitous-arps