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nicokaiser / rpi-audio-receiver

Raspberry Pi Audio Receiver with Bluetooth A2DP, AirPlay 2, and Spotify Connect
MIT License
1.38k stars 148 forks source link

connection pin #48

Closed OmegaMatze closed 4 years ago

OmegaMatze commented 4 years ago

Hallo,

i'm glad for your work - installation was easy and is working. I have only one question: how can I enable a PIN or somthing to restrict who can connect to the Pi via Bluetooth?

many Thx!

nicokaiser commented 4 years ago

That's a nice idea! Maybe this could be done by checking the GPIO pins periodically by a script (or even only at startup?) and if a jumper is set, then make the device discoverable via bluetoothctl.

Maybe something like the read/write PIN in this script: https://github.com/adafruit/Raspberry-Pi-Installer-Scripts/blob/master/read-only-fs.sh

janosfoeth commented 4 years ago

Hi, I'm not sure if @OmegaMatze meant a physical GPIO pin on the Pi. Sounds more like he's looking for a 4 digit pin for bluetooth authentication like a password.

Anyways, I like both ideas :)

nicokaiser commented 4 years ago

Oh, I see. I think requiring a Bluetooth PIN is not really supported anymore with the "Secure Simple Pairing Mode" (set in /etc/systemd/system/bthelper@.service.d/override.conf). I did not get any connection working without sspmode...

JasonLG1979 commented 4 years ago

It might be possible with bt-agent it does have a -p, --pin arg. https://manpages.debian.org/buster/bluez-tools/bt-agent.1.en.html

Although I'm not sure how it would work in NoInputNoOutput since we can't provide any feedback? the manpage says:

if the key matches, otherwise it will request the user for manual authorization.

nicokaiser commented 4 years ago

I just added a patch that switches from using an own agent implementation to bt-agent. Also, some instruction on how to enable PIN code pairing. For my setup (with USB Bluetooth dongle) this seems to work well, can anybody test this with the internal Raspberry Bluetooth module?

JasonLG1979 commented 4 years ago

The pin can be up to 6 digits right? If so it might be better for the example to be 123456?

JasonLG1979 commented 4 years ago

The docs for the DisplayPinCode method say this:

Note that the PIN will always be a 6-digit number zero-padded to 6 digits. This is for harmony with the later specification.

I know that is method is for verifying the pin from another device but my thought is what's good for the goose is good for the gander.

JasonLG1979 commented 4 years ago

You might also add that an easy way to get your Bluetooth mac address is to use hciconfig -a.

nicokaiser commented 4 years ago

Note that connections without SSP are not supported on iOS devices. I could not find a way to enable pairing with SSP and PIN.

nicokaiser commented 4 years ago

I reverted the docs about PIN pairing. It just does not work.

So, I'll close this and conclude, once again, that configuring Bluetooth on Linux is a mess and only works with an USB dongle, without a PIN code and thus without additional security (anyone can connect). Sorry.

JasonLG1979 commented 4 years ago

Predefined pins are really kinda a hack anyway. They don't really offer any sort of extra security really since they're so short they wold be crackable in about as fast as you could send 10000 guesses and there's no encryption involved so they can be sniffed. If someone is concerned about having a device that accepts all pairing requests they should just wire up a button to a couple GPIO pins to turn discoverability on and off like was mentioned previously. They make cheap button shims and hats.

https://www.adafruit.com/product/3582