ZyXEL Prestige 660HW-D1 Wireless Router 91-004-593003B Manual Do Utilizador

P-660H/HW-D Series User’s Guide

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Chapter 10 Firewall Configuration

The following table describes the labels in this screen.

For DoS attacks, the ZyXEL Device uses thresholds to determine when to drop sessions that 
do not become fully established. These thresholds apply globally to all sessions.

You can use the default threshold values, or you can change them to values more suitable to 
your security requirements.

 to configure thresholds.  

Tune these parameters when something is not working and after you have checked the firewall 
counters. These default values should work fine for most small offices. Factors influencing 
choices for threshold values are:

• The maximum number of opened sessions.
• The minimum capacity of server backlog in your LAN network.
• The CPU power of servers in your LAN network.
• Network bandwidth. 
• Type of traffic for certain servers.

Table 62   Firewall: Anti Probing

Respond to PING 

on

The ZyXEL Device does 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 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. 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 changes back to the ZyXEL Device.

Cancel

Click Cancel to begin configuring this screen afresh.