P-661H/HW Series User’s Guide

7.4.1 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.

Note: 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.

7.4.2 Port 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 are shown in the following table. Please refer to RFC 1700 for further information about port numbers. Please also refer to the Supporting CD for more examples and details on port forwarding and NAT.

Table 51 Services and Port Numbers

SERVICES

PORT NUMBER

 

 

ECHO

7

 

 

FTP (File Transfer Protocol)

21

 

 

SMTP (Simple Mail Transfer Protocol)

25

 

 

DNS (Domain Name System)

53

 

 

Finger

79

 

 

HTTP (Hyper Text Transfer protocol or WWW, Web)

80

 

 

POP3 (Post Office Protocol)

110

 

 

NNTP (Network News Transport Protocol)

119

 

 

SNMP (Simple Network Management Protocol)

161

 

 

SNMP trap

162

 

 

PPTP (Point-to-Point Tunneling Protocol)

1723

 

 

7.4.3 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.

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Chapter 7 Network Address Translation (NAT) Screens