The administrator must bind the egress ACL filtering packets leaving the network to the internal interface on an inbound direction.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-14688	NET0921	SV-15381r2_rule		Medium

Description
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 3 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.

Description

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 3 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.

STIG	Date
Perimeter Router Security Technical Implementation Guide Cisco	2018-08-23

Details

Check Text ( C-12847r2_chk )
Review the router configuration and verify that all internal interfaces have been configured with an ACL or filter on an inbound direction.

Fix Text (F-14153r1_fix)
Bind the ingress ACL to the external interface (inbound) and the egress ACL to the internal interface (inbound).