ZyXEL Communications ZyWALL 300 User Manual

Chapter 19 Firewall

ZyWALL USG 300 User’s Guide

Your customized rules take precedence and override the ZyWALL’s default settings. The 
ZyWALL checks the schedule, user name (user’s login name on the ZyWALL), source IP 
address, destination IP address and IP protocol type of network traffic against the firewall 
rules (in the order you list them). When the traffic matches a rule, the ZyWALL takes the 
action specified in the rule. 

For example, if you want to allow a specific user from any computer to access one zone by 
logging in to the ZyWALL, you can set up a rule based on the user name only. If you also 
apply a schedule to the firewall rule, the user can only access the network at the scheduled 
time. A user-aware firewall rule is activated whenever the user logs in to the ZyWALL and 
will be disabled after the user logs out of the ZyWALL.

Firewall rules are grouped based on the direction of travel of packets to which they apply.

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The LAN, WAN, DMZ, and WLAN are default zones. Refer to 

 for more information on zones.

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If you create a new zone, there is no default firewall rule for it and any packets 
sent to or from the new zone are allowed.

The following table shows you the default firewall rules that inspect packets going through the 
ZyWALL.

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The ZyWALL checks the firewall rules before the application patrol rules for 
traffic going through the ZyWALL. 

If you want to use a service, make sure both the firewall and application patrol allow the 
service’s packets to go through the ZyWALL. 

You can use the firewall to block a service with a static port number. To block a service using 
a flexible/dynamic port number by inspecting the service’s packets, you need to use 
application patrol. See the chapter about application patrol for more information.