Title

The Juniper perimeter router must be configured to filter ingress traffic at the external interface on an inbound direction. (Cat II impact)

Discussion

Firewall 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 firewall filters 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.

Check Content

This requirement is not applicable for the DODIN Backbone. Review the router configuration to verify that the ingress firewall filter is bound to the external interface in an inbound direction. [edit interfaces] <external interface> { unit <number> { family inet { filter { input inbound-ipv4; } } family inet6 { filter { input inbound-ipv6; } } } } Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter. The deny-all filter is created once per family and can be reused across multiple lists. For example: input-list [ permit_mgt permit_routing_protocols default-deny ]; If the router is not configured to filter traffic entering the network at the external interface in an inbound direction, this is a finding.

Fix Text

This requirement is not applicable for the DODIN Backbone. Bind the ingress firewall filter to the external interface (inbound). set interfaces <external interface name> unit <number> family inet filter input inbound-ipv4 set interfaces <external interface name> unit <number> family inet6 filter input inbound-ipv6

Additional Identifiers

Rule ID: SV-254013r844072_rule

Vulnerability ID: V-254013

Group Title: SRG-NET-000205-RTR-000004

Expert Comments

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