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V-283853

CAT II (Medium)

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

Rule ID

SV-283853r1203808_rule

STIG

Nokia Service Router OS 25.x Router Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-002385

Discussion

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.

Check Content

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.

Use the command below to verify "ICMP Unreachable" is set to Disable:

- show router interface "TO-PE2" detail | match "Unreachables"
Unreachables     : Disabled
Unreachables     : Number - 100         Time (seconds)   - 10

If ICMP unreachable notifications are enabled on any external interfaces, this is a finding.

Fix Text

Disable ICMP unreachable notifications on all external interfaces, as shown in the example below: 

- configure router interface "TO-PE2" icmp no unreachables