I control my son's internet access by opening up the (wired) router settings in my browser and filtering out the MAC address to his computer. He has figured out that he can simply unplug his computer from the router and plug it directly into the cable modem (when I'm away from home) and surf that way, bypassing the router altogether.
I can access the modem's settings at 192.168.100.1/ but there's nothing there to enable or disable it.
Short of physically removing the modem, is there a way to disable/enable it via the browser, or even remotely?
Thanks for any suggestions.
Short answer: no.
The cable modem (generally) is owned (and therefore controlled) by the cable company. If you have one issued by your cable company like that, then all you can do MAYBE is see if the cable company is willing to enable a MAC filter on the cable modem. I know this was how Time Warner cable controlled access on their system (at least, they did it several years ago).
Having said all that, you CAN buy a cable modem yourself. I've seen one (I forget the make/model) at my nearest Best Buy store, and you can search their site (and others, I'm sure).
You'd have to speak with your cable provider to make sure that they'll accept one of these units (you can probably find more with Google or even... err... Bing.
Now, the catch: I do not know if any cable modem provides what you want. They're built for simplicity. Personally, I think the ISP might be your best bet. If anything. But if you search around enough, maybe you'll find a cable modem with built in firewall/routing to do what you want. I haven't found one so far.