ZyXEL Communications P-2602 manual Remote Management Icmp, Remote Management Configuration

P-2602H(W)(L)-DxA Series User’s Guide

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

Note: If you want your device to respond to pings and requests for unauthorized services, you may also need to configure the firewall anti probing settings to match.

Figure 148 Remote Management: ICMP

The following table describes the labels in this screen.

Table 111 Remote Management: ICMP

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 ZyXEL Device 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 to	Select this option to prevent hackers from finding the ZyXEL Device by probing for
requests for	unused ports. If you select this option, the ZyXEL Device will not respond to port
unauthorized	request(s) for unused ports, thus leaving the unused ports and the ZyXEL Device
services	unseen. By default this option is not selected and the ZyXEL Device 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 ZyXEL Device's firewall
	mechanism before reaching this anti-probing mechanism. Therefore if the firewall
	mechanism blocks a probing packet, the ZyXEL Device reacts based on the
	corresponding firewall policy to send a TCP reset packet for a blocked TCP packet
	or an ICMP port-unreachable packet for a blocked UDP packets or just drop the
	packets without sending a response packet.
Apply	Click Apply to save your customized settings and exit this screen.
Cancel	Click Cancel to begin configuring this screen afresh.

276 Chapter 21 Remote Management Configuration