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V-256030

CAT II (Medium)

The Arista router must be configured to have gratuitous ARP disabled on all external interfaces.

Rule ID

SV-256030r882432_rule

STIG

Arista MLS EOS 4.2x Router Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-002385

Discussion

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.

Check Content

Review the configuration to determine if gratuitous ARP is disabled on all external interfaces.

By default, Arista router interfaces reject gratuitous ARP request packets. To verify the gratuitous ARP is disabled, execute the command "sh run int ethernet YY".

These commands enable/disable gratuitous ARP packet acceptance on.

Enable 

interface Ethernet 2
  arp gratuitous accept
  
Disable

interface Ethernet 2
  no arp gratuitous accept

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

Fix Text

Disable gratuitous ARP on all external interfaces.

Disable

interface Ethernet 2
  no arp gratuitous accept