The Cisco switch must be configured to have Internet Control Message Protocol (ICMP) unreachable messages disabled on all external interfaces.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-221084 | SRG-NET-000362-RTR-000113 | CISC-RT-000170 | SV-221084r999693_rule | 2024-12-20 | 3 |
| Description |
|---|
| The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Switches automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis. |
| ℹ️ Check |
|---|
| Review the switch configuration to determine if it is compliant with this requirement. The ip unreachables command must not be found on any interface as shown in the example below: interface Ethernet2/7 no switchport ip address x.22.4.2/30 ip unreachables If ICMP unreachable notifications are sent from any external interfaces, this is a finding. |
| ✔️ Fix |
|---|
| Disable ip unreachables on all external interfaces as shown below: SW1(config)# int e2/7 SW1(config-if)# no ip unreachables SW1(config-if)# end |