P100IH ISDN Router

Field

Description

Option/Example

This field is N/A for One-to-One, Many-to-

One and Server types.

Note: For all Local and Global IPs, the End IP address must begin after the IP Start

address, i.e., you cannot have an End IP address beginning before the Start IP address.

4.5.2NAT Server Sets

A NAT Server Set is a list of LAN side servers mapped to external ports (similar to the old SUA menu 15.1 before).

Multiple Servers Behind NAT

If you wish, you can make inside servers for different services, e.g., web or FTP, visible to the outside users, even though NAT makes your whole inside network appear as a single machine to the outside world. A service is identified by the port number, e.g., web service is on port 80 and FTP on port 21.

As an example (see the following figure), if you have a web server at 192.168.1.36 and an FTP server 192.168.1.33, then you need to specify for port 80 (web) the server at IP address 192.168.1.36 and for port 21 (FTP) another at IP address 192.168.1.33.

Please note that a server can support more than one service, e.g., a server can provide both FTP and DNS service, while another provides only web service.

Figure 4-12 Multiple Servers Behind NAT

NAT

4-13

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ZyXEL Communications 1001H manual NAT Server Sets, Multiple Servers Behind NAT