5. The IRC server sends a return message to your modem router using the NAT-assigned source port (for
example, port 33333) as the destination port and also sends an “identify” message to your modem router
with destination port 113.
6. When your modem 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 modem router
restores the original address information replaced by NAT and sends this reply message to your computer.
7. When your modem 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 modem router replaces
the message’s destination IP address with your computer’s IP address and forwards the message to
8. When you finish your chat session, your modem router eventually senses a period of inactivity in the
communications. The modem 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
Nighthawk AC1900 WiFi VDSL/ADSL Modem Router Model D7000v2