The Port Forwarding Screen - ZyXEL Communications P-660H-61 User Manual

Table 41 Network > NAT > General (continued)
LABEL
Max NAT/Firewall
Session Per User
Apply
Cancel

9.3 The Port Forwarding Screen

Use this screen to forward incoming service requests to the server(s) on your local network.
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.
The most often used port numbers and services are shown in
to RFC 1700 for further information about port numbers.
Note: 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.
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.
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
ADSL Router Series User's Guide
DESCRIPTION
When computers use peer to peer applications, such as file sharing applications, they
need to establish NAT sessions. If you do not limit the number of NAT sessions a single
client can establish, this can result in all of the available NAT sessions being used. In
this case, no additional NAT sessions can be established, and users may not be able to
access the Internet.
Each NAT session establishes a corresponding firewall session. Use this field to limit the
number of NAT/Firewall sessions client computers can establish through the ZyXEL
Device.
If your network has a small number of clients using peer to peer applications, you can
raise this number to ensure that their performance is not degraded by the number of
NAT sessions they can establish. If your network has a large number of users using peer
to peer applications, you can lower this number to ensure no single client is exhausting
all of the available NAT sessions.
Click this to save your changes.
Click this to restore your previously saved settings.
Chapter 9 Network Address Translation (NAT)
Appendix F on page 351. Please refer
153