CISC-RT-000170 - The Cisco router must be configured to have Internet Control Message Protocol (ICMP) unreachable messages disabled on all external interfaces.

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Information

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.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

Disable ip unreachables on all external interfaces as shown below.

RP/0/0/CPU0:R3(config)#int g0/0/0/1
RP/0/0/CPU0:R3(config-if)#ipv4 unreachables disable

Alternative - DODIN Backbone

Configure the PE router to rate limit ICMP unreachable messages as shown in the example below.

RP/0/0/CPU0:R3(config)#icmp ipv4 rate-limit unreachable df 1000
RP/0/0/CPU0:R3(config)#icmp ipv4 rate-limit unreachable 60000
RP/0/0/CPU0:R3(config)#end

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Cisco_IOS-XR_Router_Y21M04_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-5, CAT|II, CCI|CCI-002385, Rule-ID|SV-216746r531087_rule, STIG-ID|CISC-RT-000170, STIG-Legacy|SV-105837, STIG-Legacy|V-96699, Vuln-ID|V-216746

Plugin: Cisco

Control ID: c3b7a604e53ebe8d8274ff19cdb69086e18d5efe4a20d34ba8e6cb54ba3d8e8c