frbncis/pi-crust

Pi Zero W based approach to using Barrier with devices on disparate networks

Pi Crust

THIS IS A WORK IN PROGRESS!

Use Raspberry Pi Zero W as hardware barrier client for machines that you can't install the software barrier client on!

The Pi Zero W will connect with your barrier server and sends keyboard and mouse controls to the client machine as if it was a USB keyboard and mouse.

In theory, as long as the machine supports USB HID devices, Pi Crust should be able to control it.

How Does this Work?

It's pretty simple.

The Pi Zero W runs the barrier client and behaves just like another barrier client.

When control changes to the Pi Zero W via barrier, the barrier client will emit X11 mouse and keyboard events. Those events are then captured and forwarded over the USB OTG interface to the end host.

How To Run

Rough instructions at the moment.

1. Install dependencies on the Pi Zero W on fresh Raspberry Pi OS Lite installation

sudo apt-get install --no-install-recommends xserver-xorg
sudo apt-get install --y barrier xinit x11-xserver-utils xserver-xorg-video-dummy

2. Configure the Pi Zero W for keyboard emulation https://www.isticktoit.net/?p=1383

3. Configure the dummy X11 display: https://gist.github.com/divinity76/ce210b5dbcd9ea7d0585ac403caef577

4. On the machine with the keyboard and mouse, start barriers.

5. On the Pi Zero W, configure barrierc (some steps in the barrier intsall seem to have been missed)

mkdir -p ~/.local/share/barrier/SSL/Fingerprints
nano ~/.local/share/barrier/SSL/Fingerprints/TrustedServers.txt
# Add Server Fingerprint to TrustedServers.txt

5. Install dev dependencies on your Pi Zero

sudo apt-get install libx11-dev

6. Clone the code to your Pi Zero

7. Using tmux, start X11 and barrierc

• X11

startx

• barrierc

barrierc -d DEBUG1 -f --name kvm-01 --enable-crypto --restart 10.160.0.196

8. Compile the code in this repository and run it to forward X11 keyboard/mouse events over to USB.

make all && ./bin/kvm /dev/hidg0

References/Credits

• https://github.com/debauchee/barrier - Provides the network transport for mouse and keyboard commands between computers
• https://www.isticktoit.net/?p=1383 - Tobias Girstmair's instructions on using the Pi Zero W as a USB device, as well as his sample code for USB HID scancodes.
• https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf - USB HID Usage Tables
• https://wiki.osdev.org/USB_Human_Interface_Devices - Human readable description on how USB HID devices work
• https://gist.github.com/javiercantero/7753445 - Sample code for interfacing with X11.
• https://gist.github.com/divinity76/ce210b5dbcd9ea7d0585ac403caef577 - Setting up X11 dummy devices
• http://manpages.ubuntu.com/manpages/xenial/man8/usbhid-dump.8.html - usbhid-dump for viewing USB HID reports coming in for debugging
• https://eleccelerator.com/tutorial-about-usb-hid-report-descriptors/ - amazing tutorial on USB HID report descriptors
• https://eleccelerator.com/usbdescreqparser/ - USB HID report descriptor parser

pi-crust's Issues

Wrong usage message

Hi Francis,

I am trying to set up the pi-crust. When I try the last command I get the following error:
Usage: ./bin/kvm <device file> <layout> <unicode>
But looking at the code in src/xreadkeys.cpp I see that the program needs 2 parameter: P_DEV_KEYBOARD and P_DEV_MOUSE. I think that the first parameter should be "/dev/hidg0" which is the keyboard on my pi (it works I think, I could test it) but I am absolutely not sure about P_DEV_MOUSE.
On https://www.isticktoit.net/?p=1383 I could not find a config to set up a mouse driver.

What do I have to pass as a second parameter? Do I have to add a config section in /usr/bin/isticktoit_usb for the mouse device?

Thanks in advance and best regards,
Boris