You said: HOW IS THIS NOT USER INTERACTION?!?!? I asked if there is a computer on the internal network that doesn't do anything -- that means SENDING NO PACKETS to the router -
Now, I wouldn't place all my bets on his answer and I am calling on someone out there to clear up my question. If NAT really does only allow inbound connections with a preliminary request as he suggests, it seems that the only way to get an "unauthorized" packet behind the router is by some flaw in the firmware of the device.
If you are not offering any services to the Internet, yes. If you are, then you have ports open on the router, redirecting to real machines, which may be running software which can be exploited.
Now, I wouldn't place all my bets on his answer and I am calling on
someone out there to clear up my question. If NAT really does only
allow inbound connections with a preliminary request as he suggests, it
seems that the only way to get an "unauthorized" packet behind the
router is by some flaw in the firmware of the device.
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