ZyXEL Communications ZyWALL USG 300 User Manual page 304

Chapter 16 Virtual Servers
SMTP server's IP address (192.168.1.21). This is also called Destination NAT
(DNAT)
Figure 195 NAT 1:1 Example Virtual Server
LAN
Destination 192.168.1.21 Destination 1.1.1.1
NAT
SMTP
SMTP
192.168.1.21
The ge3 interface has a different IP address than 1.1.1.1, so in order for the
ZyWALL gateway to be able to do ARP resolution correctly, you need to create a
ge3 virtual server entry. In the Network > Virtual Server screen, click the +
symbol and create a new virtual server entry as shown next. This entry maps TCP
port 25 (SMTP) traffic coming to IP address 1.1.1.1 on ge3 to the IP address of
the SMTP server (192.168.1.21 defined in the LAN_SMTP object). In this
example the SMTP server also uses port 25, so the Mapped Port is set to 25. The
following sections describe how to manually configure corresponding policy routes
for NAT 1:1 mapping and loopback so the options to have the ZyWALL
automatically create them are not selected here.
Figure 196 Create a Virtual Server
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