SMC Networks SMC7404BRA EU manual 4-43, Parameter, Defaults, Description, Stateful Packet

			FIREWALL
	Parameter	Defaults	Description
Stateful Packet			This option allows you to select different
Inspection			application types that are using dynamic port
			numbers. If you wish to use Stateful Packet
			Inspection (SPI) for blocking packets, click on
			the “Yes” radio button in the “Enable SPI and
			Anti-DoS firewall protection” field and then
			check the inspection type that you need, such as
			Packet Fragmentation, TCP Connection, UDP
			Session, FTP Service, H.323 Service, and TFTP
			Service.
			It is called a “stateful” packet inspection because
			it examines the contents of the packet to
			determine what the state of the communication
			is, i.e. it ensures that the stated destination
			computer has previously requested the current
			communication. This is a way of ensuring that all
			communications are initiated by the recipient
			computer and are taking place only with sources
			that are known and trusted from previous
			interactions. In addition to being more rigorous
			in their inspection of packets, stateful inspection
			firewalls also close off ports until connection to
			the specific port is requested.
			When particular types of traffic are checked, only
			the particular type of traffic initiated from the
			Internal LAN will be allowed. For example, if the
			user only checks “FTP Service” in the Stateful
			Packet Inspection section, all incoming traffic
			will be blocked except FTP connections initiated
			from the local LAN.
Hacker Prevention
Feature
	Discard Ping	Discard	Prevents a PING on the Gateway’s WAN port
	from WAN		from being routed to the network.

4-43