Chapter 10 Network Address Translation (NAT) Screens

Many residential broadband ISP accounts do not allow you to run any server processes (such as a Web or FTP server) from your location. Your ISP may periodically check for servers and may suspend your account if it discovers any active services at your location. If you are unsure, refer to your ISP.

10.4.1 Default Server IP Address

In addition to the servers for specified services, NAT supports a default server IP address. A default server receives packets from ports that are not specified in this screen.

"If you do not assign a Default Server IP address, the ZyXEL Device discards all packets received for ports that are not specified here or in the remote management setup.

10.4.2Port Forwarding: Services and Port Numbers

Use the Port Forwarding screen to forward incoming service requests to the server(s) on your local network.

The most often used port numbers and services are shown in Appendix F on page 417. Please refer to RFC 1700 for further information about port numbers.

10.4.3 Configuring Servers Behind Port Forwarding (Example)

Let's say 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 80 Multiple Servers Behind NAT Example

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P-2602H(W)(L)-DxA User’s Guide