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V-216567

CAT II (Medium)

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

Rule ID

SV-216567r856186_rule

STIG

Cisco IOS Router RTR Security Technical Implementation Guide

Version

V3R4

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. Redirect ICMP messages are commonly used by attackers for network mapping and diagnosis.

Check Content

Review the router configuration to verify that the no ip redirects command has been configured on all external interfaces as shown in the example below.

interface GigabitEthernet0/1
 ip address x.x.x.x 255.255.255.0
 no ip redirects

If ICMP Redirect messages are enabled on any external interfaces, this is a finding.

Fix Text

Disable ICMP redirects on all external interfaces as shown in the example below.

R4(config)#int g0/1
R4(config-if)#no ip redirects