ZyXEL Communications HS100/HS100W manual Configuring Security, Icmp

HomeSafe User’s Guide

14.8 Configuring Security

To change your HomeSafe’s security settings, click REMOTE MGMT, then the Security tab. The screen appears as shown.

If an outside user attempts to probe an unsupported port on your HomeSafe, an ICMP response packet is automatically returned. This allows the outside user to know the HomeSafe exists. Your HomeSafe supports anti-probing, which prevents the ICMP response packet from being sent. This keeps outsiders from discovering your HomeSafe when unsupported ports are probed.

	Figure 14-8 Remote Management : Security
The following table describes the labels in this screen.
	Table 14-7 Remote Management : Security
LABEL	DESCRIPTION
ICMP	Internet Control Message Protocol is a message control and error-reporting protocol
	between a host server and a gateway to the Internet. ICMP uses Internet Protocol
	(IP) datagrams, but the messages are processed by the TCP/IP software and directly
	apparent to the application user.
Respond to Ping	The HomeSafe will not respond to any incoming Ping requests when Disable is
on	selected. Select LAN to reply to incoming LAN Ping requests. Select WAN to reply to
	incoming WAN Ping requests. Otherwise select LAN & WAN to reply to both
	incoming LAN and WAN Ping requests.
Do not respond	Select this option to prevent hackers from finding the HomeSafe by probing for
to requests for	unused ports. If you select this option, the HomeSafe will not respond to port
unauthorized	request(s) for unused ports, thus leaving the unused ports and the HomeSafe
services	unseen. By default this option is not selected and the HomeSafe will reply with an
	ICMP Port Unreachable packet for a port probe on its unused UDP ports, and a TCP
	Reset packet for a port probe on its unused TCP ports.
	Note that the probing packets must first traverse the HomeSafe's firewall mechanism
	before reaching this anti-probing mechanism. Therefore if the firewall mechanism
	blocks a probing packet, the HomeSafe reacts based on the firewall policy, which by
	default, is to send a TCP reset packet for a blocked TCP packet. You can use the
	command "sys firewall tcprst rst [onoff]" to change this policy. When the firewall
	mechanism blocks a UDP packet, it drops the packet without sending a response
	packet.

14-10 Remote Management Screens