Nat 1:1 Virtual Server; Nat 1:1 Policy Route; Figure 92 Nat 1:1 Example Virtual Server; Figure 93 Create A Virtual Server - ZyXEL Communications Unified Security Gateway ZyWALL 1000 User Manual

6.6.2 NAT 1:1 Virtual Server

This section sets up a virtual server rule that changes the destination of SMTP traffic coming
to IP address 1.1.1.1 at the ZyWALL's ge3 (WAN) interface, to the LAN SMTP server's IP
address (192.168.1.21). This is also called Destination NAT (DNAT)

Figure 92 NAT 1:1 Example Virtual Server

192.168.1.21
The ge3 WAN 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). In this example the SMTP
server also uses port 25, so the Mapped Port is set to 25.

Figure 93 Create a Virtual Server

6.6.3 NAT 1:1 Policy Route

This section sets up a policy route for the traffic coming from the LAN SMTP server to the
ZyWALL's ge1 (LAN) interface. It changes the source address from 192.168.1.21 to 1.1.1.1.
This is also called Source NAT (SNAT). It sends the traffic out through ge3 (a WAN
interface).
ZyWALL USG 1000 User's Guide
Destination 192.168.1.21
NAT
SMTP
Chapter 6 Tutorials
Destination 1.1.1.1
SMTP
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