ZyXEL Communications vantage cnm ユーザーズマニュアル

 Chapter 6 Device Security Settings

Vantage CNM User’s Guide

The following table describes the labels in this screen.

Click Device Operation in the menu bar and then click Device Configuration > Security > 
Firewall > Threshold in the navigation panel to bring up the next screen. The global values 
specified for the threshold and timeout apply to all TCP connections.

Figure 54   Device Operation > Device Configuration > Security > Firewall > Threshold

Table 43   Device Operation > Device Configuration > Security > Firewall > Anti-Probing

Respond to PING 
on

Select the interfaces on which you want the device to reply to incoming Ping 
requests. 

Do not respond to 
requests for 
unauthorized 
services.

Select this option to prevent hackers from finding the device by probing for unused 
ports. If you select this option, the device will not respond to port request(s) for 
unused ports, thus leaving the unused ports and the device unseen. If this option 
is not selected, the 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 device's firewall rule checks 
before reaching this anti-probing mechanism. Therefore if a firewall rule stops a 
probing packet, the 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.

Apply

Click Apply to save your changes back to the device.

Reset

Click Reset to begin configuring this screen afresh.