I have two FireTVs in my house. My Home Assistant are on a different network than my FireTVs. There is a firewall between the two networks not allowing communication.
Every once and a while, Home Assistant will tell me it has discovered a FireTV HomeKit Device.
How is it finding a FireTV on an unrelated network?
I am trying to determine which one of the two FireTVs its discovering, but there isn't anything useful that tells me which. Is there a way outside of connecting the TVs to the same network?
I set up HomeKit integration to talk to my Ecobee thermostat. It is on the same network as Home Assistant.
HomeKit uses mDNS (aka Bonjour) for device discovery over Ethernet & WiFi.
If you have one logical subnet over two interfaces with a transparent firewall, then it may be that some mDNS announcements are getting through on firewall boot up before the firewall rules are installed.
If you have two separate subnets with a router/firewall between then then by default mDNS won't be routed from one to the other. But some routers support mDNS mirroring. If this is switched on, then it might be bypassing your firewall rules or again, might get a few announcements through at boot time before they are installed.
If you can give us more information about your firewall (make, model, firmware version, config etc.) we might be able to advise.
Alarming isn’t it? Somehow they are leaking data. What else is being exfiltrated? I recommend a WireShark session on each of the network segments to see what is happening behind the scenes. You may have a network misconfiguration or something else you overlooked or are not aware of.
Don’t be tempted to initially filter WireShark traffic just by the FireTV MAC, as there may be dynamic MACs at work, or MITM activity happening. Start broad, identify known unrelated devices to exclude, and then start to narrow down to understand what is left over to more closely look at. Hint: When the FireTV is initially powered on is a good place to start looking at what activity it triggers.