The router must be configured to have Internet Control Message Protocol (ICMP) unreachable notifications disabled on all external interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-78223	SRG-NET-000362-RTR-000113	SV-92929r1_rule		Medium

Description
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis.

STIG	Date
Router Security Requirements Guide	2019-09-27

Details

Check Text ( C-77779r1_chk )
Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP unreachable notifications out to any external interfaces. If ICMP unreachable notifications are enabled on any external interfaces, this is a finding.

Fix Text (F-84951r1_fix)
Disable ICMP unreachable notifications on all external interfaces.