My dishwasher has a MAC address. So do dozens of other things in my house, and I have no idea what most of them send home.
Is there a router (OpenWrt or similar) that blocks every new device by default, then lets me unblock it by picking its make and model from a crowdsourced allowlist to let through only what it needs to function?
So the best option would be to just keep the machine blocked, or limit it to an "IoT" VLAN that doesn't have Internet connectivity. And if the dishwasher needs the Internet to simply work, get rid of it.
Otherwise you can flash pfsense or opnsense on to compatible hardware which can also be configured with pfBlockerNG or similar to provide the same blocking functionality plus firewall functionality but it's probably a bit harder to set up.
I'm imagining software that does what my router does now - displays all devices connected to my network. When they are attached, they get a DHCP address but all other network access is blocked by default - so they probably don't work. It has a web page showing just blocked devices. You enter the make / model / year. Since devices don't work until you've entered it, there is likely just one, so it should be easy.
The TL;DR is to change the default from "everything is allowed" to "everything is blocked, apart from endpoints required by the device". Blocking is pretty easy software / hardware wise, but knowing "endpoints required by the device" is much harder.
Commercial entities maintaining blocklists are incentivised to sell access to make a little extra on the side - see Adblock Plus’s “Acceptable Ads” programme. Brave is another example - they inserted affiliate codes. The only arrangement I've seen that works over the long term is open source maintained lists - like uBlock Origin.
This would be far safer than what we have now. It would not just make snooping much harder; blocking access by default (even from internal devices) defangs most CVEs. It would probably prevent many devices auto patching - but that doesn't matter so much now the internet can't get to them, and on the upside it makes it hard for Samsung to upgrade their $3,000 fridges to display ads. Getting to keep the device you paid for would be a nice change.
All this seems kinda obvious to me, which is why this is an "Ask HN". If I've thought of it, then it's highly likely someone is already 10 steps ahead and has already done it.