NearLock

Automatic PC lock when your Bluetooth device disconnects

NearLock monitors a paired Bluetooth device (like your phone) and automatically locks your Windows PC when you walk away. When you return and your device reconnects, you simply unlock your PC as usual.

Features

• Bluetooth Classic & BLE detection - Works with both classic Bluetooth and Bluetooth Low Energy devices
• System tray application - Runs quietly in the background with status indicator
• First-run wizard - Easy setup to select your Bluetooth device
• Live log viewer - Monitor connection status in real-time
• Start on boot - Optional automatic startup with Windows
• Low resource usage - Minimal CPU and memory footprint
• Single instance - Prevents multiple instances from running

How It Works

1. NearLock continuously monitors the connection status of your selected Bluetooth device
2. When the device disconnects (you walk away), a countdown starts (default: 20 seconds)
3. After the countdown, a confirmation scan is performed to avoid false positives
4. If the device is still not detected, your PC is automatically locked
5. When you return and your device reconnects, simply unlock your PC normally

Requirements

• Windows 10/11 (64-bit recommended)
• Bluetooth adapter enabled on your PC
• Paired Bluetooth device (phone, smartwatch, etc.)
• PowerShell 5.1+ (included with Windows 10/11)

⚠️ Important: Phone Link Required for Reliable Detection

For reliable presence detection, your phone must be connected via Phone Link (Mobile Connecté). Simply having Bluetooth enabled is not enough - modern phones don't continuously advertise their presence to save battery.

Setup Phone Link:

1. Install "Link to Windows" app on your phone
2. Open Phone Link on your PC (pre-installed on Windows 10/11)
3. Pair your phone following the instructions
4. Keep Phone Link running for continuous Bluetooth connection

Installation

Option 1: Download Release (Recommended)

1. Download NearLock.exe from the Releases page
2. Place it in a folder of your choice (e.g., C:\Program Files\NearLock)
3. Run NearLock.exe
4. Follow the first-run wizard to select your Bluetooth device

Option 2: Run from Source

1. Clone this repository
2. Run NearLock-Single.ps1 with PowerShell:

   powershell -ExecutionPolicy Bypass -File NearLock-Single.ps1

Usage

System Tray Icon

NearLock runs in the system tray with a colored eye icon indicating status:

Icon Color	Status
🟢 Green	Device connected
🟠 Orange	Searching for device
⚫ Grey	Disabled or no device configured

Tray Menu Options

• Auto-lock: Enabled/Disabled - Toggle automatic locking on/off
• Settings... - Change Bluetooth device or configure startup options
• View Logs - Open live log window to monitor activity
• Exit - Close NearLock

Settings

Access settings from the tray menu to:

• Change Device - Select a different paired Bluetooth device
• Start on boot - Enable/disable automatic startup with Windows

Building from Source

Prerequisites

• PowerShell 5.1 or later
• ps2exe (for compiling to EXE)

Build Steps

1. Clone the repository:

   git clone https://github.com/baptisteba/NearLock.git
   cd NearLock

2. Install ps2exe (if not already installed):

   Install-Module ps2exe -Scope CurrentUser

3. Compile to EXE:

   Invoke-ps2exe -inputFile "NearLock-Single.ps1" -outputFile "NearLock.exe" -noConsole -title "NearLock" -version "1.2.1.0"

Configuration

Configuration is stored in %LOCALAPPDATA%\NearLock\config.json:

{
  "deviceMAC": "AA:BB:CC:DD:EE:FF",
  "deviceName": "My Phone",
  "startOnBoot": true
}

Logs are stored in %LOCALAPPDATA%\NearLock\logs\.

Technical Details

Detection Methods

NearLock uses multiple detection methods for reliability:

1. Bluetooth Classic API - Uses Windows bthprops.cpl to check device connection status (requires Phone Link)
2. BLE GATT Proximity - Uses WinRT to attempt GATT connection with uncached mode for accurate presence detection
3. Radio Scan - Performs active Bluetooth inquiry as fallback confirmation before locking

Timing Parameters

Parameter	Default	Description
Poll interval	4 seconds	How often to check device status
Lock threshold	20 seconds	Time before locking after disconnect
Grace period	30 seconds	Delay after system wake before monitoring

Security

• Uses Windows native LockWorkStation() API to lock the PC
• No network communication - all processing is local
• No data collection or telemetry

Troubleshooting

Device not detected

1. Ensure your Bluetooth device is paired in Windows Settings
2. Make sure Bluetooth is enabled on both your PC and device
3. Try re-pairing the device

False locks

If NearLock locks your PC while you're still nearby:

• Your device may have intermittent Bluetooth connectivity
• Try moving closer to your PC
• Check for Bluetooth interference from other devices

High CPU usage

If you notice high CPU usage:

• Check the logs for repeated errors
• Try restarting NearLock
• Ensure your Bluetooth driver is up to date

License

MIT License - see LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Acknowledgments

• Inspired by the macOS/iOS Near Lock app
• Uses Windows Bluetooth APIs via P/Invoke
• Built with PowerShell and Windows Forms