16

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.

"The virtual server changes the destination address of packets. This is also known as Destination NAT (DNAT).

 

309

ZyWALL USG 100/200 Series User’s Guide