V-216670

Discussion

Vulnerability assessments must be reviewed by the System Administrator, and protocols must be approved by the Information Assurance (IA) staff before entering the enclave. ACLs are the first line of defense in a layered security approach. They permit authorized packets and deny unauthorized packets based on port or service type. They enhance the posture of the network by not allowing packets to reach a potential target within the security domain. The lists provided are highly susceptible ports and services that should be blocked or limited as much as possible without adversely affecting customer requirements. Auditing packets attempting to penetrate the network that are stopped by an ACL will allow network administrators to broaden their protective ring and more tightly define the scope of operation.

Check Content

This requirement is not applicable for the DODIN Backbone.

Review the router configuration to verify that the ingress ACL is in accordance with DoD 8551.1.

Step 1: Verify that an inbound ACL is configured on all external interfaces.

interface GigabitEthernet0/2
 ip address x.11.1.2 255.255.255.254
 ip access-group EXTERNAL_ACL_INBOUND in

Step 2. Review the inbound ACL to verify that it is filtering traffic in accordance with DoD 8551.1.

ip access-list extended EXTERNAL_ACL_INBOUND
 permit tcp any any established
 permit tcp host x.11.1.1 eq bgp host x.11.1.2
 permit tcp host x.11.1.1 host x.11.1.2 eq bgp
 permit icmp host x.11.1.1 host x.11.1.2 echo
 permit icmp host x.11.1.1 host x.11.1.2 echo-reply
 …
 …    < must be in accordance with DoD Instruction 8551.1>
 …
deny   ip any any log-input

If the router does not filter traffic in accordance with the guidelines contained in DoD 8551.1, this is a finding.