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Chapter 22 Firewall

ZyWALL USG 50 User’s Guide

The ZyWALL then sends it to the computer on the LAN1 in Subnet 1. 

Figure 222   Using Virtual Interfaces to Avoid Asymmetrical Routes    

Click Configuration > Firewall to open the Firewall screen. Use this screen to 
enable or disable the firewall and asymmetrical routes, set a maximum number of 
sessions per host, and display the configured firewall rules. Specify from which 
zone packets come and to which zone packets travel to display only the rules 
specific to the selected direction. Note the following.

• If you enable intra-zone traffic blocking (see the chapter about zones), the 

firewall automatically creates (implicit) rules to deny packet passage between 

the interfaces in the specified zone.

• Besides configuring the firewall, you also need to configure NAT rules to allow 

computers on the WAN to access LAN devices. See 

more information.

• The ZyWALL applies NAT (Destination NAT) settings before applying the firewall 

rules. So for example, if you configure a NAT entry that sends WAN traffic to a 

LAN IP address, when you configure a corresponding firewall rule to allow the 

traffic, you  need to set the LAN IP address as the destination. See 

 for an example.

LAN1