NETGEAR Nighthawk X6S User Manual page 173

Nighthawk X6S AC3000 Tri-Band WiFi Router Model R7900P
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 router.
3. Your router creates an entry in its internal session table describing this communication session between
your computer and the IRC server.Your 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 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 router using the NAT-assigned source port (for example,
port 33333) as the destination port and also sends an "identify" message to your router with destination
port 113.
6. When your 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 router restores the
original address information replaced by NAT and sends this reply message to your computer.
7. When your 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 router replaces the message's
destination IP address with your computer's IP address and forwards the message to your computer.
8. When you finish your chat session, your router eventually senses a period of inactivity in the
communications. The router then removes the session information from its session table, and incoming
traffic is no longer accepted on port numbers 33333 or 113.
Manage Port Forwarding and Port Triggering
173