D6200 WiFi DSL Modem Router
1.The user of a remote computer opens a browser and requests a web page from www.example.com, which resolves to the public IP address of your WiFi DSL modem router. The remote computer composes a web page request message with the following destination information:
•Destination address. The IP address of www.example.com, which is the address of your WiFi DSL modem router.
•Destination port number. 80, which is the standard port number for a web server process.
The remote computer then sends this request message through the Internet to your WiFi DSL modem router.
2.Your WiFi DSL modem router receives the request message and looks in its rules table for any rules covering the disposition of incoming port 80 traffic. Your port forwarding rule specifies that incoming port 80 traffic should be forwarded to local IP address 192.168.1.123. Therefore, your WiFi DSL modem router modifies the destination information in the request message:
The destination address is replaced with 192.168.1.123.
Your WiFi DSL modem router then sends this request message to your local network.
3.Your web server at 192.168.1.123 receives the request and composes a return message with the requested web page data. Your web server then sends this reply message to your WiFi DSL modem router.
4.Your WiFi DSL modem router performs Network Address Translation (NAT) on the source IP address, and sends this request message through the Internet to the remote computer, which displays the web page from www.example.com.
To configure port forwarding, you need to know which inbound ports the application needs. Usually you can determine this information by contacting the publisher of the application or the relevant user groups and newsgroups.
How Port Forwarding Differs from Port Triggering
The following points summarize the differences between port forwarding and port triggering:
•Port triggering can be used by any computer on your network, although only one computer can use it at a time.
•Port forwarding is configured for a single computer on your network.
•Port triggering does not require that you know the computer’s IP address in advance. The IP address is captured automatically.
•Port forwarding requires that you specify the computer’s IP address during configuration, and the IP address can never change.
•Port triggering requires specific outbound traffic to open the inbound ports, and the triggered ports are closed after a period of no activity.
•Port forwarding is always active and does not need to be triggered.
Advanced Settings
118
