ZyXEL Communications ZyXEL ZyWALL USG-1000, User Manual

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ZyWALL USG 2000 User’s Guide
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Virtual Servers
16.1 Virtual Servers Overview
Virtual servers are computers on a private network behind the ZyWALL that you
make available outside the private network. If the ZyWALL has only one public IP
address, you can make the computers in the private network available by using
ports to forward packets to the appropriate private IP address.
Suppose you want to assign ports 21-25 to one FTP, Telnet and SMTP server (A in
the example), port 80 to another (B in the example) and assign a default server IP
address of 192.168.1.35 to a third (C in the example). You assign the LAN IP
addresses and the ISP assigns the WAN IP address. The NAT network appears as a
single host on the Internet.
Figure 165 Multiple Servers Behind NAT Example
16.1.1 What You Can Do in the Virtual Server Screens
Use the Virtual Server screens (see Section 16.2 on page 274 ) to view and
manage the list of virtual servers and see their configuration details. You can also
create new virtual servers and edit or delete existing ones.
16.1.2 What You Need to Know About Virtual Servers
Virtual server is also known as port forwarding or port translation.
Note: The virtual server changes the destination address of packets. This is also
known as Destination NAT (DNAT).