Router Mode Application Example: Port Triggering For Internet Relay Chat - NETGEAR WAC124 User Manual

AC2000 802.11ac Wireless Access Point/Router WAC124
8. Click the Apply button.
Your settings are saved.
Router mode application example: Port triggering for
Internet Relay Chat
Some application servers, such as FTP and IRC servers, send replies to multiple port
numbers. Using port triggering, you can tell the access point/router to open more
incoming ports when a particular outgoing port starts a session.
An example is Internet Relay Chat (IRC). Your computer connects to an IRC server at
destination port 6667. The IRC server not only responds to your originating source port
but also sends an "identify" message to your computer on port 113. Using port triggering,
you can tell the access point/router, "When you initiate a session with destination port
6667, you must also allow incoming traffic on port 113 to reach the originating
computer."
The following sequence shows the effects of this port triggering rule:
1. You open an IRC client program to start a chat session on your computer.
2. Your IRC client composes a request message to an IRC server using a destination
port number of 6667, the standard port number for an IRC server process. Your
computer then sends this request message to your access point/router.
3. Your access point/router creates an entry in its internal session table describing this
communication session between your computer and the IRC server. Your access
point/router stores the original information, performs Network Address Translation
(NAT) on the source address and port, and sends this request message through the
Internet to the IRC server.
4. Noting your port triggering rule and observing the destination port number of 6667,
your access point/router creates another session entry to send any incoming port
113 traffic to your computer.
5. The IRC server sends a return message to your access point/router using the
NAT-assigned source port (for example, port 33333) as the destination port and also
sends an "identify" message to your access point/router with destination port 113.
6. When your access point/router receives the incoming message to destination port
33333, it checks its session table to see if a session is active for port number 33333.
Finding an active session, the access point/router restores the original address
information replaced by NAT and sends this reply message to your computer.
7. When your access point/router receives the incoming message to destination port
113, it checks its session table and finds an active session for port 113 associated
with your computer. The access point/router replaces the message's destination IP
address with your computer's IP address and forwards the message to your computer.
Router Mode: Manage Port
Forwarding and Port Triggering
237 User Manual