tunnel challenge stuff

HMI software stack:

• vanilla HTML/CSS/JS webpage as UI
• display webpage fullscreen using Chromium in kiosk mode
• use websocat to convert TCP socket connections to WebSocket
• nginx for static hosting

bonus bits

• mock WebSocket server

  websocat -s 8081

• mock TCP server

  socat stdio tcp-listen:8079

  or

  nc -lp 8079

  (both of these need while :; do ... ; done loops to keep them running indefinitely)
• forward TCP server to WebSocket

  websocat --text ws-listen:127.0.0.1:8081 tcp:127.0.0.1:8079