ZyXEL Communications 200 Series - Manual (Page 309)

ZyWALL USG 100/200 Series 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 211 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 310 ) 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.
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The virtual server changes the destination address of packets. This is also
known as Destination NAT (DNAT).