Can a Smart TV piggy back the internet of a HDMI device?
from xavier666@lemmy.umucat.day to selfhosted@lemmy.world on 05 Nov 08:11
https://lemmy.umucat.day/post/782966

I am unsure if this is the right community but here it goes.

I want to buy a smart TV and I will plug a HDMI device into it. I want to stream my games and movies to the TV via moonlight/jellyfin. I heard about ACR and how it can be used to recognize content running on our TV which will be then sold off to advertisement companies/data brokers.

Say I have isolated the traffic of the TV (the OS of the TV specifically) to a separate VLAN. But the connected HDMI device is connected to the internet. Can the TV use this network to effectively “phone home”? Do HDMI devices have this capability?

PS: I know modern HDMI dongles can also share data but I at least have the option to change the device/use a mini PC.

#selfhosted

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empireOfLove2@lemmy.dbzer0.com on 05 Nov 08:23 next collapse

Ethernet over HDMI does exist as a standard, but iirc it requires the device manufacturer on both ends of the cable to have a special implementation, and also requires a special cable that has the Ethernet data lanes included. I’m not sure any modern displays implement it anymore, it kinda died because it sucked and wasn’t that useful.

xavier666@lemmy.umucat.day on 05 Nov 08:44 next collapse

Ethernet over HDMI

Thanks for this. Looks like it’s a rare protocol.

Excerpt from the article

If you have an HEC-compatible device, it will most likely be self-described somewhere in the user’s manual. Unfortunately, this technology is rarely implemented, and you would be hard-pressed to find a device that uses HEC. Through our research, we were unable to find any modern consumer device that uses HEC.

I am slightly relieved.

Blackmist@feddit.uk on 05 Nov 15:00 collapse

They can barely make the other device turn on reliably, let alone have enough planets aligned to let the other device access the internet.

MTK@lemmy.world on 05 Nov 08:29 next collapse

It’s very very unlikely that your TV and your device connected to it both support and enable ethernet over HDMI by default. But if you are unsure you can test it by connecting and seeing if the TV is getting a connection.

Personally I also opened my TV and disconnected the wifi card since in theory the TV could also just try to connect to any open wifi in the area without me knowing, but to each their own threat model.

xavier666@lemmy.umucat.day on 05 Nov 08:39 collapse

But if you are unsure you can test it by connecting and seeing if the TV is getting a connection

I might be a bit paranoid but I suspect that in such a scenario, the TV will report that there is no connection but will keep on sending data to remote servers.

Fortunately in my area there are no open WiFi networks but disconnecting the WiFi card is a good suggestion. Wish we had physical kill-switches in all devices.

MTK@lemmy.world on 05 Nov 08:45 next collapse

You can sniff the network and see if the TV is connecting anywhere.

non_burglar@lemmy.world on 05 Nov 16:15 collapse

Don’t trust the TV, put short or suricata on that in passive bridge mode. Heck, even TCP-dump should see some activity when you turn on the TV.

metaStatic@kbin.earth on 05 Nov 08:24 next collapse

I wouldn't trust modern e-waste as far as I could throw it.

do you NEED a terrestrial receiver?

xavier666@lemmy.umucat.day on 05 Nov 08:48 collapse

Right now, I have one of those cheap google sticks. But I want to eventually shift to an open-source solution using an RPi or a mini-pc.

grue@lemmy.world on 05 Nov 08:50 next collapse

Demonstrating the need for jail breaking firmware for smart TVs (and repealing the DMCA anti-circumvention clause that enforces Tivoization) in two different ways at once:

  1. You can’t use ethernet-ovet-HDMI on your smart TV because you don’t have enough control over it even though it’s running Linux.
  2. You only care about the feature in the first place because you don’t have enough control over it even though it’s running Linux.
GreenShimada@lemmy.world on 05 Nov 10:07 next collapse

Agreeing with @empireOfLove2@lemmy.dbzer0.com that you’re not going to stumble into internet over HDMI between two devices. This is a zero percent concern, IMO.

xavier666@lemmy.umucat.day on 05 Nov 10:38 collapse

Security by obsoleteness

jaaake@lemmy.world on 05 Nov 15:31 collapse

It’s not just the obsoleteness of it, it’s the fact that any device that is on the other end of the TV’s HDMI cable would need to be actively routing internet traffic into the HDMI connection. What device would do that? Any device that’s using the TV as output for itself has no reason to also include network access.

Auli@lemmy.ca on 05 Nov 13:03 next collapse

Noo long answer Noooo. Even if device had it you need a cable that supports it.

bluGill@fedia.io on 05 Nov 14:41 collapse

Yes. However as others have already said odds are you don't have the right devices. Still if you really work at it everything exists. Start by selecting one of the few TVs that support it, then get a good HDMI cable, make sure you have a video card that supports it, with drivers for the OS (you might have to write them yourself), then just setup networking. This would be an interesting hack, I'd love to see someone get it working and show their setup, but it is otherwise useless and will be a lot of work.

AbidanYre@lemmy.world on 05 Nov 15:35 collapse

I think you misread OP’s intent.

bluGill@fedia.io on 05 Nov 16:09 collapse

After verifying that OP's intent was met I gave a more fun answer that abused the letter of what was asked.