ZyXEL p-2802h-i1 Manual Do Utilizador

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Chapter 9 Network Address Translation (NAT) Screens
P-2802H(W)(L)-I Series User’s Guide
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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.
9.4.1  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.
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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.
9.4.2  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 and services are shown in 
refer to RFC 1700 for further information about port numbers. 
9.4.3  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.