3Com 3CRWDR101A-75 manual Firewall, Router limits access for incoming traffic at the WAN port

Firewall 67

Firewall	From these screens, you can configure settings for the firewall.
	Your Router is equipped with a firewall that will protect your network
	from a wide array of common hacker attacks including Ping of Death
	(PoD) and Denial of Service (DoS) attacks. You can turn the firewall
	function off if needed. Turning off the firewall protection will not leave
	your network completely vulnerable to hacker attacks, but 3Com
	recommends that you leave the firewall enabled whenever possible.
	SPI Stateful Packet Inspection (SPI) - The Intrusion Detection Feature of the
	Router limits access for incoming traffic at the WAN port.
	This feature is called a "stateful" packet inspection, because it examines
	the contents of the packet to determine the state of the communications;
	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.
	Figure 53 Firewall Screen

To enable the firewall function:

1Select the level of protection (High, Medium, or Low) that you desire from the Firewall level drop-down menu.

2Click Apply.