Soldered, wired, and coded

The Internet Watchdog

A Raspberry Pi that fixes the internet connection itself, and falls back to mobile data with a secure tunnel home when it can’t.

My Raspberry Pi carries a USB UMTS SIM card on a cheap data plan and constantly monitors whether the internet connection is up.

If it is down for too long, the Pi first tries to repair it itself: Restarting the router, or power-cycling it through a smart plug. If that does not bring the connection back, it fails over to mobile internet via UMTS, using the Sakis3G library, opens an SSH reverse proxy tunnel, and sends me the access details.

That way I never lose contact with my smart home hub and home automation, even when the primary line is completely down.

What it does

Continuously monitors internet availability

Self-repair: Router restart or smart-plug power cycle

Automatic fallback to mobile internet (UMTS / Sakis3G)

Opens an SSH reverse proxy tunnel over mobile data

Sends access details so I can always reach the smart home hub

Under the hood

  • Raspberry Pi
  • USB UMTS modem
  • Sakis3G
  • SSH reverse tunnel
  • Smart plug power cycling
  • Shell scripting