ZyXEL Communications FMG3024-D10A User Manual

Chapter 13 Firewall

FMG3024-D10A / FMG3025-D10A Series User’s Guide

Note: Incorrectly configuring the firewall may block valid access or introduce security 

risks to the Device and your protected network. Use caution when creating or 

deleting firewall rules and test your rules after you configure them.

Consider these security ramifications before creating a rule:

Does this rule stop LAN users from accessing critical resources on the Internet? For example, if IRC 
is blocked, are there users that require this service?

Is it possible to modify the rule to be more specific? For example, if IRC is blocked for all users, will 
a rule that blocks just certain users be more effective?

Does a rule that allows Internet users access to resources on the LAN create a security 
vulnerability? For example, if FTP ports (TCP 20, 21) are allowed from the Internet to the LAN, 
Internet users may be able to connect to computers with running FTP servers.

Does this rule conflict with any existing rules?

Once these questions have been answered, adding rules is simply a matter of entering the 
information into the correct fields in the web configurator screens.