OpenKVM

DIY KVM device for remote-controlling a computer. KVM stands for Keyboard & Video & Mouse.

A side system on a rackmount server, IPMI in Dell Server for example.

Unlike the IP-KVM, this project respects VNC protocol.

Just like the MIT license says, no warranty or guarantee.

My dev walkthrough is in WALKTHROUGH.md.

And do NOT use for any illegal purposes.

TODO

• Remove OpenCV, see WALKTHROUGH.md
• Installation script
  • Register as a system service
  • Start on boot
• VNC authentication
  • DES encryption in Golang can NOT directly apply to VNC Authentication
  • Http Basic Auth in web page and API
• More effective to calculate the difference between frames
  • Balance between the power of SBC and the network efficiency
  • Or achieve more support for noVNC, beyond rfc6143
• OTG as keyboard and mouse, see Linux USB Gadget API
• Using a single command to get the frame for Video, like

  v4l2-ctl --device=/dev/video0 --stream-mmap --stream-count=1 --stream-to=- --set-fmt-video="width=640,height=480,pixelformat=MJPG"

Dev Environment

Hardware

NONE of them is sponsored, use them at your own risk!

Essential hardware are:

• A computer that can run Golang
  • An old computer
  • SBC
    • RaspberryPi
    • OrangePi
    • BTT-Pi
    • etc...
  • Maybe an Android phone?
• HDMI Recorder, see WALKTHROUGH.md for more details.
  • Or a webcam with an always-on monitor.
    • I know...this is a stupid way -- pointing a camera to a screen.
• Keyboard & Mouse Emulator
  • ESP32-S3
  • ESP32-S2
  • Arduino?
  • Some other device that supports USB HID output.
    • HID over BLE is not recommended, because it may not work in BIOS.
• Relay and/or delayed relay

My Gears

• SBC: OrangePi 3 LTS
  • ¥241 RMB ≈ $34 USD
• HDMI Recorder: hagibis UHC07
  • ¥69 RMB ≈ $10 USD
  • ⚠️ This device ONLY supports 1920x1080 and 3840x2160.
• Keyboard & Mouse: ESP32-S3
  • I bought a third-party one of WeAct ESP32 S3 (A) DevKitC 1.
  • ¥52 RMB ≈ $7.5 USD
• 5V relay * 2, 5V delayed relay * 1
  • ¥15 RMB ≈ $2 USD

Others

• Test Device:
  • RaspberryPi 2B
  • A Windows computer
  • Ubuntu 24.04 x86_64
• Some SD cards.
• Some USB Type-C2C/C2A cables.
• A HDMI cable.
• Some power supplies.

It costs about ¥300 RMB ≈ 40 USD.

Price is for reference only, the actual price may vary.

Software

• GO
• OpenCV
• PlatformIO
• noVNC

Diagram

飞书文档, FeiShu Doc

Installation

Debian ARM64

1. Install GO dev kit

   sudo apt-get update
   sudo apt-get install -y wget curl ffmpeg v4l-utils
   GO_ZIP="go1.23.3.linux-arm64.tar.gz"
   wget "https://go.dev/dl/$GO_ZIP"
   sudo rm -rf /usr/local/go && sudo tar -C /usr/local -xzf "$GO_ZIP"

2. Pull this repo

   sudo apt-get update
   sudo apt-get install -y git
   git clone https://github.com/allape/openkvm.git

3. Get noNVC

   git clone --depth 1 https://github.com/novnc/noVNC.git
   
   # [Optional] You can run noVNC separately
   python3 -m http.server --directory noVNC/ 8081

4. Flash ESP32-S3
   • PIO: See WALKTHROUGH.md for reason of removal.
   • Arduino
     • Open Perferences -> Additional Board Manager URLs -> Add https://espressif.github.io/arduino-esp32/package_esp32_dev_index.json
       • Click HERE for more details
     • Open km/esp32s3-arduino/main/main.ino with Arduino IDE
     • Select board ESP32S3 Dev Module and corresponding port
     • Click Upload
5. Run or build repo

   cd openkvm
   
   go mod tidy
   go mod download
   
   cp kvm.new.toml kvm.toml
   
   # Find out serial port
   dmesg | grep tty
   
   # Edit this file to apply your settings
   vim kvm.toml
   
   # Should run with super user privilege
   sudo go run .
   
   #go build -o openkvm .
   #sudo ./openkvm

6. Open browser and go to http://ip:8080/vnc.html, then click Connect
   • Hostname and port may vary depending on your settings
7. Open http://ip:8080/ui/button.html to control the relay

Credits

• Listed in go.mod
• Roboto Font
• noVNC
• PlatformIO
• ESP-IDF
• ESP32-Arduino
• Raspberry Pi Imager
• KeyMap