The firewall implementation must apply ingress filters entering the network to the external interface in the inbound direction.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
SRG-NET-000205-FW-000121	SRG-NET-000205-FW-000121	SRG-NET-000205-FW-000121_rule		Medium

Description
Filters 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 filters for restricting access to services on the router itself as well as for filtering traffic passing through the router. It should be noted that some operating systems default filters are applied to the outbound queue. The more secure solution is to apply the filter to the inbound queue for three reasons: The device can protect itself before damage is inflicted. The input port is still known, and can be filtered. *It is more efficient to filter packets before forwarding them.

Description

Filters 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 filters for restricting access to services on the router itself as well as for filtering traffic passing through the router. It should be noted that some operating systems default filters are applied to the outbound queue. The more secure solution is to apply the filter to the inbound queue for three reasons: *The device can protect itself before damage is inflicted. *The input port is still known, and can be filtered. *It is more efficient to filter packets before forwarding them.

STIG	Date
Firewall Security Requirements Guide	2014-07-07

Details

Check Text ( C-SRG-NET-000205-FW-000121_chk )
Review the configuration of the firewall implementation and verify that ingress filters are applied to external interfaces in an inbound direction. If the ingress filters are not applied to the external interfaces in an inbound direction, this is a finding.

Fix Text (F-SRG-NET-000205-FW-000121_fix)
Apply the ingress filters to external interfaces in an inbound direction.