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    Stateless Firewall Filter Types

    This topic covers the following information:

    Firewall Filters

    The Junos OS standard stateless firewall filters support a rich set of packet-matching criteria that you can use to match on specific traffic and perform specific actions, such as forwarding or dropping packets that match the criteria you specify. You can configure firewall filters to protect the local router or to protect another device that is either directly or indirectly connected to the local router. For example, you can use the filters to restrict the local packets that pass from the router’s physical interfaces to the Routing Engine. Such filters are useful in protecting the IP services that run on the Routing Engine, such as Telnet, SSH, and BGP, from denial-of-service attacks.

    Note: If you configured targeted broadcast for virtual routing and forwarding (VRF) by including the forward-and-send-to-re statement, any firewall filter that is configured on the Routing Engine loopback interface (lo0) cannot be applied to the targeted broadcast packets that are forwarded to the Routing Engine. This is because broadcast packets are forwarded as flood next hop traffic and not as local next hop traffic, and you can only apply a firewall filter to local next hop routes for traffic directed toward the Routing Engine.

    Service Filters

    A service filter defines packet-filtering (a set of match conditions and a set of actions) for IPv4 or IPv6 traffic. You can apply a service filter to the inbound or outbound traffic at an adaptive services interface to perform packet filtering on traffic before it is accepted for service processing. You can also apply a service filter to the traffic that is returning to the services interface after service processing to perform postservice processing.

    Service filters filter IPv4 and IPv6 traffic only and can be applied to logical interfaces on Adaptive Services PICs, MultiServices PICs, and MultiServices DPCs only. Service filters are not supported on Branch SRX devices.

    Simple Filters

    Simple filters are supported on Gigabit Ethernet intelligent queuing (IQ2) and Enhanced Queuing Dense Port Concentrator (EQ DPC) interfaces only. Unlike standard filters, simple filters support IPv4 traffic only and have a number of restrictions. For example, you cannot configure a terminating action for a simple filter. Simple filters always accept packets. Also, simple filters can be applied only as input filters. They are not supported on outbound traffic. Simple filters are recommended for metropolitan Ethernet applications.

    Modified: 2017-08-31