ZyWALL User's Guide

Chapter 16 Virtual Servers
ZyWALL USG 100/200 Series User’s Guide
320
Figure 227 Create a Policy Route
Now the LAN1 SMTP server replies to the ZyWALL’s LAN1 IP address and the ZyWALL
changes the source address to 1.1.1.1 before sending it to the LAN1 user’s computer. The
source in the return traffic matches the original destination address (1.1.1.1) and the LAN1
user can use the LAN1 SMTP server.
Figure 228 NAT Loopback Successful
192.168.1.21
LAN1
192.168.1.89
Source 1.1.1.1
SMTP
NAT
Source 192.168.1.21
SMTP