ZyXEL Communications NBG4615 User Manual

 Chapter 24 Firewall

NBG4615 User’s Guide

Don't enable any local service (such as NTP) that you don't use. Any enabled service could present 
a potential security risk. A determined hacker might be able to find creative ways to misuse the 
enabled services to access the firewall or the network. 

For local services that are enabled, protect against misuse. Protect by configuring the services to 
communicate only with specific peers, and protect by configuring rules to block packets for the 
services at specific interfaces. 

Protect against IP spoofing by making sure the firewall is active. 

Keep the firewall in a secured (locked) room. 

Use this screen to enable or disable the NBG4615’s firewall, and set up firewall logs. Click Security 
> Firewall to open the General screen.

Security > Firewall > General l

The following table describes the labels in this screen.

If an outside user attempts to probe an unsupported port on your NBG4615, an ICMP response 
packet is automatically returned. This allows the outside user to know the NBG4615 exists. Use this 
screen to prevent the ICMP response packet from being sent. This keeps outsiders from discovering 
your NBG4615 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.

Security > Firewall > General 

Enable Firewall

Select this check box to activate the firewall. The NBG4615 performs access 
control and protects against Denial of Service (DoS) attacks when the firewall is 
activated.

Apply

Click Apply to save the settings. 

Cancel

Click Cancel to start configuring this screen again.