Boot sequence, init, captive portal, and recovery

How boot sequence runs

1. Make RasPi calling your own startup script. In /etc/rc.local:

nohup /home/pi/Orchids/init.sh &

2. In /home/pi/Orchids/init.sh:

• Detect WiFi SSID set or got already an IP by DHCP.
• If no SSID and no IP then activate Captive portal => Call captive script and exit.
• From here normal boot continues:
  • Kill all uncontrolled ssh sessions if any, including remaining of recovery script.
  • Call reverse HTTP and reverse SSH recovery script.

How Captive script works

Purpose:

Configure RasPi with SSID and password of your WiFi. Advanced purpose: set static IP for WLAN or for LAN interface.

Principle:

• Switch the RasPi into AP mode with known SSID (OrchidCareAP, for instance) and with no password (for simplicity).
• Optional: Run HTTP server and Captive portal page with SSID and passphrase fields (at least).
• Accept SSH (or optional HTTP) connections in order to configure your WiFi SSID + passphrase.
• Once configured, propose user to reboot the RasPi. Automatic reboot may cause problems and recommended to be supervised by user.

How Recovery script works

Purpose:

Make sure the connection from VPS to RasPi works. If not then recover it. RasPI <--ReverseSSH/HTTP--> VPS <--SSH/HTTP--> User

Principle (similar for HTTP and SSH):

• Access VPS from RasPi to VPS.
• Try to get relevant info from RasPi: curl or SSH to appropriate reversed port (10080 or 10022).
• Count failures.
• If exceeded count limit then kill all reverse tunnel processes and try to establish new ones and reset the counter.