I'm getting ready to start networking at my local college and I can't wait to ask a bunch of questions, many of which have been answered on here thankfully. But I have one that is left unanswered: What are the possible security flaws of Port Triggering? I'm still wrapping my head around it, but is this description accurate?
Local machine "1" is sending data through (out of) a general port for a service (e.g. IRC) to the internet. This port is now occupied with outgoing traffic and cannot intake external traffic? Thus it tells the router to forward (open) a port for that same external service to return data to local machine "1".
My "flow chart":
Local Machine1 192.168.0.5:6667 --> LAN --> Router --> ISP --> IRC Server --> ISP --> Router --> Local Machine1:6668
Note if anyone could improve this wikipedia page (add citations) the human race would greatly appreciate you for it. It would also be a good idea to add some of the following tags: port-triggering Let me know if you do eh, cheers.