ZyXEL Communications P-660 series Guia do Utilizador descarregar pdf (Página 80)

Chapter 6 Network Address Translation (NAT) Screens

P-660R-F1 Series User’s Guide

6.4 Port Forwarding

A port forwarding set is a list of inside (behind NAT on the LAN) servers, for example, web or FTP,

that you can make visible to the outside world even though NAT makes your whole inside network

appear as a single computer to the outside world.

You may enter a single port number or a range of port numbers to be forwarded, and the local IP

address of the desired server. The port number identifies a service; for example, web service is on

port 80 and FTP on port 21. In some cases, such as for unknown services or where one server can

support more than one service (for example both FTP and web service), it might be better to

specify a range of port numbers. You can allocate a server IP address that corresponds to a port or

a range of ports.

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.

6.4.1 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.

6.4.2 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.

Table 26 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

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