How Port Forwarding Differs From Port Triggering - NETGEAR WNR612v2 - Wireless-N 150 Router User Manual

Wireless-N 150 Router WNR612v2 User Manual
The user of a remote computer opens Internet Explorer and requests a Web page from
1.
www.example.com, which resolves to the public IP address of your router. The remote
computer composes a Web page request message with the following destination
information:
The destination address is the IP address of www.example.com, which is the address
•
of your router.
The destination port number is 80, the standard port number for a Web server
•
process.
The remote computer then sends this request message through the Internet to your
router.
Your router receives the request message and looks in its rules table for any rules covering
2.
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 router
modifies the destination information in the request message:
The destination address is replaced with 192.168.1.123.
Your router then sends this request message to your local network.
Your Web server at 192.168.1.123 receives the request and composes a return message
3.
with the requested Web page data. Your Web server then sends this reply message to your
router.
Your router performs Network Address Translation (NAT) on the source IP address, and
4.
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.
You usually can determine this information by contacting the publisher of the application or
user groups or news groups.

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.
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Port triggering does not need to 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,
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and the IP address must never change.
Port triggering requires specific outbound traffic to open the inbound ports, and the
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triggered ports are closed after a period of no activity.
Port forwarding is always active and does not need to be triggered.
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Chapter 6: Fine-Tuning Your Network | 57