ZyXEL P-660N-T1A User Guide - Page 153
The Port Forwarding Screen
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Chapter 9 Network Address Translation (NAT) Table 41 Network > NAT > General (continued) LABEL DESCRIPTION Max NAT/Firewall Session Per User 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. Apply Cancel Click this to save your changes. Click this to restore your previously saved settings. 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 Appendix F on page 351. Please refer 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 153