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Chapter 16 Virtual Servers
ZyWALL USG 100/200 Series User’s Guide
317
Figure 221 Create a Firewall Rule
NAT Loopback Example
The NAT 1:1 Example on page 313 maps a public IP address to the private IP address of a
LAN1 SMTP mail server to allow users to access the SMTP mail server from the WAN.
LAN1 users can also use an IP address to access the mail server. However, you need to
configure NAT loopback for LAN1 users to use a domain name to access the server.
Figure 222 LAN1 Computer Queries the DNS Server
A LAN1 user computer at IP address 192.168.1.89 queries the domain name (xxx.LAN-
SMTP.com in this example) from a public DNS server and gets the SMTP server’s 1-1 NAT
mapped public IP address of 1.1.1.1.
192.168.1.21
xxx.LAN-SMTP.com = ?
LAN1
DNS
192.168.1.89
xxx.LAN-SMTP.com = 1.1.1.1
1.1.1.1