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 Chapter 17 NAT

ZyWALL USG 50 User’s Guide

Here is more detailed information about NAT on the ZyWALL.

Suppose a NAT 1:1 rule maps a public IP address to the private IP address of a 
LAN SMTP e-mail server to give WAN users access. NAT loopback allows other 
users to also use the rule’s original IP to access the mail server. 

Firewall

By default the firewall blocks incoming connections from external 
addresses. After you configure your NAT rule settings, click the Firewall 
link to configure a firewall rule to allow the NAT rule’s traffic to come in.

The ZyWALL checks NAT rules before it applies To-ZyWALL firewall rules, 
so To-ZyWALL firewall rules do not apply to traffic that is forwarded by 
NAT rules. The ZyWALL still checks other firewall rules according to the 
source IP address and mapped IP address.

OK

Click OK to save your changes back to the ZyWALL.

Cancel

Click Cancel to return to the NAT summary screen without creating the 
NAT rule (if it is new) or saving any changes (if it already exists).

Table 93   Configuration > Network > NAT > Add (continued)