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)