Pairing Bluetooth Keyboard with Raspberry Pi 3, without GUI

In brief 

The latest Raspberry Pi 3 now comes with its own built in  Bluetooth 4.1/Low Energy (LE) support. Here below, I just share how I did the pairing between my bluetooth keyboard and the raspberry pi.

Infrastructure  

- Raspberry Pi 3, running Raspbian Jessie Lite
- Bluetooth Keyboard (in my case Active Strike Pro mini )
- On my laptop, I run Debian 8
- The Raspberry Pi 3 (rpi) is already connected through the Wi-Fi and it has a static local IP assigned (192.168.0.28). Therefore I could accept any time the rpi via SSH :
  $ ssh pi@192.168.0.28

Steps

1. Install the BlueTooth library on rpi as a 'pi' user :
 $ sudo apt-get update
 $ sudo apt-get upgrade
 $ sudo apt-get install bluetooth


2. On the rpi, start the interactive bluetoothctl command line (as a pi user NOT AS ROOT):
 $ bluetoothctl -a
 [NEW] Controller B8:27:EB:1A:8A:A7 raspberrypi [default]
 Agent registered
 [bluethooth]# 

 3. Power up the controller:
  [bluethooth]# power on
  Changing power on succeeded
  [CHG] Controller B8:27:EB:1A:8A:A7 Powered: yes

 4. Set the controller to look only for keyboards:
  [bluethooth]# agent KeyboardOnly
  Agent registered

5. Set the controller to make the keyboard as a default agent:
  [bluethooth]# default-agent
  Default agent request successful

6. Set the controller in the 'pairable' mode:
  [bluethooth]# pairable on
  Changing pairable on succeeded

7. Enable the 'pairing mode' of your Bluetooth Keyboard (in Active Strike Pro mini, by pressing :  Fn + C) and scan with your rpi controller:
  [bluethooth]# scan on
  Discovery started

  [CHG] Controller B8:27:EB:1A:8A:A7 Discovering: yes

  [NEW] Device 20:73:00:16:12 Bluetooth 3.0 Keyboard 

  ... 




8. Do the pairing, wait for the PIN code:
  [bluethooth]# pair 20:73:00:16:12
  Attempting to pair with 20:73:00:16:12

  [CHG] Device 20:73:00:16:12 Connected: yes

  [agent] PIN code: 785148

9. Quickly, type the PIN code on the keyboard and press Enter:
  [CHG] Device 20:73:00:16:12 Modalias: usb:v04E8p7021d011B
  [CHG] Device 20:73:00:16:12 UUIDs
           0001000-0000-8000-00805f9b34fb
  [CHG] Device 20:73:00:16:12 Paired: Yes   

  Pairing successful  

10. Make the device a trusted device
  [bluethooth]# trust 20:73:00:16:12

  [CHG] Device 20:73:00:16:12 trust succeeded

  Changing 20:73:00:16:12 trust succeeded




11. Connect to the device
  [bluethooth]# connect 20:73:00:16:12
  Attempting to connect with 20:73:00:16:12 

  [CHG] Device 20:73:00:16:12 Connected: yes

  Connection successful




12. Leave the bluetoothctl command line
  [bluethooth]# quit

Done !