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V-269889

CAT II (Medium)

The Dell OS10 Router must be configured to have Internet Control Message Protocol (ICMP) unreachable notifications disabled on all external interfaces.

Rule ID

SV-269889r1052052_rule

STIG

Dell OS10 Switch Router Security Technical Implementation Guide

Version

V1R2

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.

Verify the "ip unreachables" command is not configured on any external interfaces. Note: the default setting has ICMP unreachable notifications disabled, so if "ip unreachables" is not present in the interface configuration then it is disabled. 
 !
 interface ethernet1/1/4
  ip unreachables

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

Fix Text

Disable ICMP unreachable notifications on all external interfaces.

OS10(config)# interface ethernet 1/1/4
OS10(conf-if-eth1/1/4)# no ip unreachables