ZyXEL Communications G-2000 Plus - Manual (Page 168)

ZyAIR G-2000 Plus User’s Guide
167 Chapter 12 Remote Management Screens
Figure 72 Security
The following table describes the labels in this screen.
Table 56 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
on
The ZyAIR 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. Otherwise select LAN & WAN to reply to both
incoming LAN and WAN Ping requests.
Do not respond to
requests for
unauthorized
services
Select this option to prevent hackers from finding the ZyAIR by probing for unused
ports. If you select this option, the ZyAIR will not respond to port request(s) for
unused ports, thus leaving the unused ports and the ZyAIR unseen. By default this
option is not selected and the ZyAIR 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 ZyAIR's firewall mechanism
before reaching this anti-probing mechanism. Therefore if the firewall mechanism
blocks a probing packet, the ZyAIR 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 [on|off]" to change this policy. When the firewall
mechanism blocks a UDP packet, it drops the packet without sending a response
packet.
Apply Click Apply to save your customized settings and exit this screen.
Reset Click Reset to begin configuring this screen afresh.