ZyXEL Communications P-2612HW-F1 User Manual page 369

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 203 Advanced > Remote Management > ICMP
The following table describes the labels in this screen.
Table 120 Advanced > Remote Management > ICMP
LABEL
ICMP
Respond to
Ping on
Do not respond
to requests for
unauthorized
services
P-2612HW-F1 User's Guide
DESCRIPTION
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.
The ZyXEL Device will not respond to any incoming Ping requests when
Disable is selected.
• Select LAN to reply to incoming LAN Ping requests.
• Select WAN to reply to incoming WAN Ping requests.
• Select LAN & WAN to reply to both incoming LAN and WAN Ping
requests.
• Select WLAN & WAN to reply to both incoming WLAN and WAN Ping
requests.
• Select WLAN & LAN to reply to both incoming WLAN and LAN Ping
requests.
• Select WLAN to reply to incoming WLAN Ping requests.
Select this option to prevent hackers from finding the ZyXEL Device by
probing for unused ports. If you select this option, the ZyXEL Device will
not respond to port request(s) for unused ports, thus leaving the unused
ports and the ZyXEL Device unseen. If this option is not selected, 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 rule checks before reaching this anti-probing mechanism.
Therefore if a firewall rule stops a probing packet, the ZyXEL Device
reacts based on the firewall rule to either 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.
Chapter 20 Remote Management
369