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martin_0004
Asked: 2016-04-28 11:23:03 +0800 CST

bluetoothctl - What is a bluetooth agent?

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I am using the bluetoothctl utility to set up Bluetooth connections between computers and Raspberry Pis.

In bluetoothctl, I can see there is something called an "agent", and by looking at most of tutorials, this "agent" has to be set "on" to create connections. I am trying to understand what is a bluetooth agent.

1) What is a bluetooth agent ?

2) What is the "default-agent" command in bluetoothctl for ? Can it be the same for all connections ?

3) What is the impact of not using an agent when setting up a connection ?

4) By looking at man bluetoothctl, it is said that agents can be set a capability. What is an agent capability ? What values could be put there ?

5) Do agents only exist with bluetooth ? Are there let's say wifi agents too ?

I am fairly new to the world of Bluetooth, and the documentation for bluetoothctl is quite limited... Any information would be appreciated.

bluetooth

1 Answers

  1. Best Answer

    The Bluetooth agent is what manages the Bluetooth 'pairing code'. It can either respond to a 'pairing code' coming in, or can send one out.

    The default-agent should work for you. You say you're new to Bluetooth, so I suggest you go with the default for now.

    Not using an agent will mean the 2 devices cannot negotiate the 'pairing code'.

    An example might help, so here's an example of what worked for me on my Raspberry Pi 3 called Shep:

    pi@shep:~/bluetooth $ bluetoothctl
[NEW] Controller B8:27:EB:B0:BC:22 shep [default]
[NEW] Device 18:9E:FC:94:8C:33 iPhone4
[bluetooth]# agent on
Agent registered
[bluetooth]# default-agent
Default agent request successful
[CHG] Device 18:9E:FC:94:8C:33 Connected: yes
[CHG] Device 18:9E:FC:94:8C:33 Connected: no

    Here I asked the iPhone to pair with Shep, and iPhone sent 680044.

    [CHG] Device 18:9E:FC:94:8C:33 Connected: yes
Request confirmation
[agent] Confirm passkey 680044 (yes/no): yes

    Or see the following if you want to set the pass key in advance:

    http://www.heatxsink.com/entry/how-to-pair-a-bluetooth-device-from-command-line-on-linux

    Setup bluetooth-agent to pass the expected pairing code

    $ bluetooth-agent 0000 &

    Obviously the '0000' could be any number.

    These agents and 'pairing codes' are specific to Bluetooth rather than Wi-Fi.

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