The Cisco switch must be configured to have Gratuitous ARP disabled on all external interfaces.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-221082 | SRG-NET-000362-RTR-000111 | CISC-RT-000150 | SV-221082r999691_rule | 2024-12-20 | 3 |
| 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. |
| ℹ️ Check |
|---|
| Review the configuration to determine if gratuitous ARP is disabled on all external interfaces as shown in the example below: interface Ethernet2/7 no switchport ip address x.22.4.2/30 no ip arp gratuitous request Note: Gratuitous ARP is enabled on all interfaces by default. If gratuitous ARP is enabled on any external interface, this is a finding. |
| ✔️ Fix |
|---|
| Disable Gratuitous ARP as shown in the example below: SW1(config)# int e2/7 SW1(config-if)# no ip arp gratuitous request SW1(config-if)# end |