Firewall Terminology

    Router

        machine has 2 interfaces, makes routing & policy decisions

        may be unix host with IP forwarding, or dedicated hardware

    Packet Filter

        Prevent unwanted packets from passing

        Allow selectively

        May redirect to inside

    Proxy (aka application gateway)

        Can forward around filter

            Listens on one interface

        Needed if

            forwarding off

            nat/masquerading for multi-connection protocols (ftp, icq, H323)