Справочник Пользователя для ZyXEL p-334

Prestige 334 User’s Guide

Chapter 13 Remote Management Screens

148

Do not respond to 

requests for 

unauthorized 

services

Select this option to prevent hackers from finding the Prestige by probing for 

unused ports. If you select this option, the Prestige will not respond to port 

request(s) for unused ports, thus leaving the unused ports and the Prestige unseen. 

By default this option is not selected and the Prestige 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 Prestige's firewall mechanism 

before reaching this anti-probing mechanism. Therefore if the firewall mechanism 

blocks a probing packet, the Prestige 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.

Table 44   Security