ZyXEL Communications NBG420N Manual Do Utilizador

Chapter 13 Firewall

NBG420N User’s Guide

Click Security > Firewall > Services. The screen appears as shown next. 
If an outside user attempts to probe an unsupported port on your NBG420N, an ICMP 
response packet is automatically returned. This allows the outside user to know the NBG420N 
exists. Use this screen to prevent the ICMP response packet from being sent. This keeps 
outsiders from discovering your NBG420N when unsupported ports are probed.
You can also use this screen to enable service blocking, enter/delete/modify the services you 
want to block and the date/time you want to block them.

Figure 98   Security > Firewall > Services 

The following table describes the labels in this screen.

Log

Select whether to create a log for packets that are traveling in the selected 

direction when the packets are blocked (Log All) or forwarded (Log Forward). Or 

select Not Log to not log any records.
To log packets related to firewall rules, make sure that Access Control under Log 

is selected in the Logs > Log Settings screen. 

Apply

Click Apply to save the settings. 

Reset

Click Reset to start configuring this screen again. 

Table 57   Security > Firewall > General 

Table 58   Security > Firewall > Services

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 NBG420N 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 all 

incoming LAN and WAN Ping requests.