The Cisco router 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-216653 | SRG-NET-000362-RTR-000111 | CISC-RT-000150 | SV-216653r855814_rule | 2024-11-25 | 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. The following command should not be found in the router 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 |
|---|
| Disable gratuitous ARP as shown in the example below: R5(config)#no ip gratuitous-arps |