Chapter 17 Network Address Translation (NAT)

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

17.5.2Port Forwarding: Services and Port Numbers

Use the Port Forwarding screen to forward incoming service requests to the server(s) on your local network. See Appendix D on page 653 for a list of commonly used services and port numbers.

The ZyWALL provides the additional safety of the DMZ ports for connecting your publicly accessible servers. This makes the LAN more secure by physically separating it from your public servers.

17.5.3 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 221 Multiple Servers Behind NAT Example

17.5.4 Port Translation

The ZyWALL can translate the destination port number or a range of port numbers of packets coming from the WAN to another destination port number or range of port numbers on the local network. When you use port forwarding without port translation, a single server on the local network can use a specific port number and be accessible to the outside world through a single WAN IP address. When you use port translation with port forwarding, multiple servers on the local network can use the same port number and still be accessible to the outside world through a single WAN IP address.

 

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ZyWALL 2 Plus User’s Guide