1 Access Port and Service Management

Default Port and Auto-Switching

The default port is 6556; when no port is specified, or the specified one is occupied, the service auto-selects an available port within 6556–9999 and records it in /opt/lynx-board/data/port.json.

Changing the Port

1. Edit the configuration file (create it if missing):

sudo nano /etc/lynx-board/env

Add or modify a PORT=number line; the port can be any unused value within 1–65535, for example:

PORT=8080

2. Restart the service to apply:

sudo systemctl restart lynx-board

3. Confirm the new port is listening:

ss -tlnp | grep lynx-board

Then open http://device-IP:8080 in a browser to verify. If the chosen port happens to be taken, the service still starts — it just switches to another available port (check data/port.json for the actual one).

4. Allow the new port in the firewall or security group and tell members the new address.

Restoring the default port: delete the PORT= line and restart the service to return to 6556.

Login Validity and Access Security

• Login validity defaults to 7 days; adjust JWT_EXPIRES_IN (e.g. 30d, 12h) in the same file, effective after restart.
• Serve external access only through an HTTPS secure proxy; keep the device port internal.

Service Management and Uninstalling

sudo systemctl status lynx-board     # status
sudo systemctl restart lynx-board    # restart
sudo systemctl stop lynx-board       # stop
journalctl -u lynx-board -f          # follow logs

• The service auto-starts on boot, restarts within 5 seconds of a crash, and gets a watchdog check every 60 seconds — normally no manual care needed.
• Uninstall: sudo dpkg -r lynx-board removes the program but keeps data and configuration — reinstalling restores everything; sudo dpkg -P lynx-board purges data and configuration too — always back up first.