ARST-RT-000380 - The Arista perimeter router must be configured to filter egress traffic at the internal interface on an inbound direction.

Information

Access lists are used to separate data traffic into that which it will route (permitted packets) and that which it will not route (denied packets). Secure configuration of routers makes use of access lists for restricting access to services on the router itself as well as for filtering traffic passing through the router.

Inbound versus Outbound: It should be noted that some operating systems default access lists are applied to the outbound queue. The more secure solution is to apply the access list to the inbound queue for three reasons:

- The router can protect itself before damage is inflicted.
- The input port is still known and can be filtered upon.
- It is more efficient to filter packets before routing them.

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

Solution

This requirement is not applicable for the DODIN backbone.

Step 1: Configure an egress ACL bound to the internal interface in an inbound direction to filter traffic leaving the network.

Leaf2(config)#ip access-list WAN_OUT
Leaf2(config-acl-WAN_OUT)#10 permit tcp any host 180.20.10.1 eq ssh telnet
Leaf2(config-acl-WAN_OUT)#20 permit ip any 190.16.10.0/24
Leaf2(config-acl-WAN_OUT)#30 permit udp any host 67.56.10.2 eq bootps snmp
Leaf2(config-acl-WAN_OUT)#40 deny tcp any 208.73.210.0 0.0.1.255
Leaf2(config-acl-WAN_OUT)#50 deny udp any 208.73.210.0 0.0.1.255
Leaf2(config-acl-WAN_OUT)#60 deny icmp any any
Leaf2(config-acl-WAN_OUT)#70 permit ip any any

Step 2: Apply the ACL inbound on all external interfaces.

Leaf2(config)#interface ethernet 8
Leaf2(config-if-Et8)# ip access-group WAN_OUT in

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_Arista_MLS_EOS_4-2x_Y24M07_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7a., CAT|II, CCI|CCI-001097, Rule-ID|SV-256019r882399_rule, STIG-ID|ARST-RT-000380, Vuln-ID|V-256019

Plugin: Arista

Control ID: e01600b49924400018c133fd5a89aa52b031b2a1df1cd59fb667d3f739cf6c5e