added bluetooth face hack by Systemic (in Slack)

docs/hacks.md

@@ -36,3 +36,67 @@ Some of this guide will work with other framebuffer-based displays.
 - Reboot.
 
 And you should be good!
+
+---
+### Pwnagotchi face via Bluetooth
+Last tested on | Pwnagotchi version | Working? | Reference
+---------------|--------------------|----------|-----------|
+2019 October 6 | Unknown | :white_check_mark: | on Android
+2019 October 6 | Unknown | :white_check_mark: | on iPad iOS 9.3.5
+
+A way to view your Pwnagotchi's ~~face~~ UI wirelessly via Bluetooth on a separate device. Refresh rate is the same as the e-ink display (every few seconds). This is NOT Bluetooth tethering; this is only Bluetooth as a server on pi side; you connect the Bluetooth and get a DHCP IP address and that's it. This hack cannot leverage the data connection.
+
+Contributed by Systemic in the Slack.
+
+##### 1. First Step
+- Comment out the Bluetooth disable line from `/boot/config.txt` : `#dtoverlay=pi3-disable-bt`
+- Change `/root/pwnagotchi/config.yml` to have `0.0.0.0` instead of `10.0.0.2` to listen as well on Bluetooth.
+- Then launch the following commands:
+
+##### 2. Install required packages.
+
+```sudo apt-get install bluez bluez-tools bridge-utils dnsmasq```
+
+##### 3. Configure Bluetooth and start it.
+```sudo modprobe bnep
+sudo brctl addbr pan0
+sudo brctl setfd pan0 0
+sudo brctl stp pan0 off
+sudo ifconfig pan0 172.26.0.1 netmask 255.255.255.0
+sudo ip link set pan0 up
+```
+
+```cat <<- EOF > /tmp/dnsmasq_bt.conf```
+
+```bind-interfaces
+port=0
+interface=pan0
+listen-address=172.26.0.1
+dhcp-range=172.26.0.2,172.26.0.100,255.255.255.0,5m
+dhcp-leasefile=/tmp/dnsmasq_bt.leases
+dhcp-authoritative
+log-dhcp
+```
+
+```EOF```
+
+```sudo dnsmasq -C /tmp/dnsmasq_bt.conf
+sudo bt-agent -c NoInputNoOutput&
+sudo bt-adapter -a hci0 --set Discoverable 1
+sudo bt-adapter -a hci0 --set DiscoverableTimeout 0
+sudo bt-adapter -a hci0 --set Pairable 1
+sudo bt-adapter -a hci0 --set PairableTimeout 0
+sudo bt-network -a hci0 -s nap pan0 &
+```
+
+##### 4. Finally: on your phone, you have to disable all existing interfaces:
+
+- Shutdown WiFi.
+- Shutdown mobile data.
+- Connect to the newly available Bluetooth device (which has the name of your Pwnagotchi).
+   - Once connected, you can test: `http://172.26.0.1:8080`
+- You can also install bettercap's UI (`sudo buttercap` then `ui.update`) 
+   - You'll need to change the http caplets to change `127.0.0.1` to `0.0.0.0`.
+- You can connect to the shell with a terminal emulator ...
+
+Happy tweaking.