User's Manual

Specify Internet Port Settings
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AC1200 WiFi Cable Modem Router Model C6220
4. Noting your port triggering rule and observing the destination port number of 6667, your
modem 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 modem router using the NAT-assigned
source port (for example, port 33333) as the destination port. The IRC server 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 your computer.
8. When you finish a 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.