BLE Lock Session

BLE Lock Session is a tool that allows you to automatically lock and unlock your computer screen using the proximity of a Bluetooth device. Ideal for users who want a hands-free lock/unlock experience (see Security Considerations before relying on it).

Features

• Automatic Lock/Unlock: Locks the screen when you move away and unlocks it when you come closer, using a Bluetooth device.
• BLE and Classic Bluetooth: Detects both BLE devices (smartwatches, bands, tags) and Classic devices (phones), even when they are not in discoverable mode.
• Flexible Configuration: Compatible with popular desktop environments or WM in Linux.
• No Python dependencies: Uses the BlueZ tools already present on most Linux systems.

Table of Contents

• Requirements
• Installation
• Configuration
• Usage
• Available Commands
• Security Considerations
• Troubleshooting
• Contributing
• License

Requirements

• Linux (tested on Arch Linux)
• Bluetooth Device
• Python 3.x
• BlueZ - bluetoothctl must be available (package bluez-utils on Arch, bluez on Debian/Ubuntu/Fedora).

No Python packages need to be installed. Classic Bluetooth devices (e.g. phones) are detected via Python's built-in Bluetooth sockets — no extra tools required.

Installation

The recommended way is pipx, which installs the ble-lock-session command from PyPI in an isolated environment:

pipx install ble-lock-session

Alternatively, with pip:

pip install --user ble-lock-session

To try the latest development version instead, install straight from the repository:

pipx install git+https://github.com/azratul/ble-lock-session.git

Or run it straight from a clone, no installation needed:

git clone https://github.com/azratul/ble-lock-session.git
cd ble-lock-session
python ble_lock_session.py --help

Configuration

The configuration file is located at ~/.config/ble-lock-session/config.ini. If it does not exist, it will be created automatically with default values.

You can modify the options in this file or use the following command:

ble-lock-session --config

You will be able to change the following parameters:

• target_address: MAC address of the Bluetooth device. Normally set by --scan, but you can also enter it directly here if you already know it.
• lock_cmd: Command to lock the screen (depending on the desktop environment).
• unlock_cmd: Command to unlock the screen (depending on the desktop environment).
• sleep_time: Time interval between checks, in seconds.
• discover_time: Total time budget for each presence check during --start, shared by Classic and BLE probes, in seconds.
• scan_duration: Overall deadline for --scan, in seconds.
• fail_checks: Consecutive failed checks required before locking (protects against transient Bluetooth failures).

With the defaults, a departure immediately after a successful check locks the session in about 30 seconds in the slowest normal case: one initial 3-second wait, three checks of up to 7 seconds, and two 3-second waits between misses.

Usage

To use BLE Lock Session, you first need to scan and save the address of your Bluetooth device:

ble-lock-session --scan

Then, to start monitoring and automatically lock/unlock:

ble-lock-session --start

You can stop the script with Ctrl + C.

Running as a systemd service

To keep the monitor running in the background without an open terminal, install the bundled user service:

mkdir -p ~/.config/systemd/user
cp ble-lock-session.service ~/.config/systemd/user/
systemctl --user enable --now ble-lock-session

Check its status and logs with:

systemctl --user status ble-lock-session
journalctl --user -u ble-lock-session -f

The unit assumes the ble-lock-session command is in ~/.local/bin (the pipx/pip install --user location). If you installed it elsewhere, edit the ExecStart= line accordingly.

Available Commands

• --scan: Searches for a Bluetooth device and saves the MAC address in the configuration.
• --start: Starts monitoring the configured device for lock/unlock.
• --config: Interactively modifies the current configuration.

Configuration Example (config.ini)

[SETTINGS]
target_address = 00:1A:7D:DA:71:13
lock_cmd = loginctl lock-session
unlock_cmd = loginctl unlock-session
sleep_time = 3
discover_time = 7
scan_duration = 60
fail_checks = 3

Security Considerations

This is a convenience tool, not an authentication mechanism. Presence is detected by Bluetooth MAC address, and MAC addresses can be spoofed by an attacker who knows (or sniffs) your device's address. Treat the automatic unlock as roughly equivalent to leaving your session open while you are nearby — do not rely on it as a security boundary. If that trade-off is not acceptable for your threat model, use only the lock half (set unlock_cmd to something harmless like true) or don't use the tool at all.

Troubleshooting

• The screen locks but never unlocks. On some distributions loginctl unlock-session requires polkit authorization. Check with loginctl unlock-session in a terminal while locked from another TTY; if it prompts or fails, add a polkit rule for your user or use a desktop-specific unlock command.
• The phone is not detected when its screen is off. Phones stop advertising over BLE when idle, so detection relies on the Classic Bluetooth link. That needs Python built with Bluetooth socket support (all major distro packages have it — if yours doesn't, --start prints a note about it) and the phone's Bluetooth radio on. Being paired with the computer makes detection most reliable.
• The phone shows as "connected" to the computer while in range. Expected: the tool keeps a lightweight Bluetooth link open to track presence silently — opening and closing one per check would make desktops that announce Bluetooth connections (e.g. blueman) spam notifications.
• "no Bluetooth adapter available". Make sure bluetoothd is running (systemctl status bluetooth) and the adapter is not blocked (rfkill list).
• The adapter is disabled while monitoring. Adapter errors count as failed checks, so the session locks after fail_checks consecutive failures instead of remaining unlocked indefinitely.
• Locks randomly while the device is next to the computer. Increase fail_checks and/or discover_time with --config; some devices advertise infrequently to save battery.

Contributing

Contributions are welcome! If you want to improve the code, add new features, or fix a bug, feel free to open a pull request.

1. Fork the project.
2. Create a branch for your new feature: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add a new feature'
4. Push the branch: git push origin my-new-feature
5. Open a pull request.

License

This project is licensed under the GPL-3.0 License.

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Thank you for trying BLE Lock Session! If you have any questions or suggestions, feel free to open an issue or contact me.