ZyXEL Prestige 660HW-D1 Wireless Router 91-004-593003B Manual Do Utilizador

P-660H/HW-D Series User’s Guide

137

Chapter 8 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.

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.

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. 

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.

Table 47   Services and Port Numbers

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