Be less of an asshole, it’s free. I’ve been sniffing packets from cable modems since the 90s. I even remember the mac address of my first network card - 00a0cc52cac7, because mediaone gave out persistent hostnames based on your mac address before they were bought by at&t. I once putty’d into my machine from Katmandu just because I could. Incidentally, when I called at&t support to find out if this would continue, their support rep had no idea what I was talking about, and after I mentioned mac addresses, he suggested I call apple.

Pretty common thing to say among white trash moms (and very possibly among non-white trash moms too, but my experience is limited…)

Every broadband connection I’ve had looks at the mac address of whatever is behind the modem, the modem essentially passes it through.

Yes. Linux can (usually though not always) drive a wifi card as an access point.

I did this 20 years ago, I can do it again…