Macbook OS Killswitch

README.md

Removing a specific USB device (like a flash drive or security key) triggers an immediate shutdown. It combines the following:

• A launch daemon that monitors USB devices
• A script that checks if your specific USB is still connected
• A shutdown command if it disappears

✅ How to Use

• Edit the DEVICE_NAME at the top of the script to match your USB stick (use system_profiler SPUSBDataType).
• Save the script as setup_usb_killswitch.sh

Run it with:

chmod +x setup_usb_killswitch.sh
sudo ./setup_usb_killswitch.sh

killswitch.sh

#!/bin/bash

# === CONFIGURE YOUR DEVICE HERE ===
DEVICE_NAME="Kingston DataTraveler"
PLIST_NAME="com.user.usbmonitor"
MONITOR_SCRIPT="/usr/local/bin/usb_monitor.sh"
PLIST_PATH="/Library/LaunchDaemons/${PLIST_NAME}.plist"
LOGFILE="/tmp/usb-monitor.log"
SUDOERS_BACKUP="/etc/sudoers.backup"

echo "🔐 Setting up USB Killswitch for device: $DEVICE_NAME"

# --- Step 1: Create the monitor script ---
echo "📄 Creating USB monitor script at $MONITOR_SCRIPT"

cat <<EOF | sudo tee "$MONITOR_SCRIPT" > /dev/null
#!/bin/bash

DEVICE_NAME="$DEVICE_NAME"
LOGFILE="$LOGFILE"

while true; do
  USB_PRESENT=\$(system_profiler SPUSBDataType | grep -q "\$DEVICE_NAME" && echo "yes" || echo "no")

  if [ "\$USB_PRESENT" == "no" ]; then
    echo "\$(date): \$DEVICE_NAME removed, initiating shutdown" >> "\$LOGFILE"
    sudo /sbin/shutdown -h now
    exit
  fi

  sleep 2
done
EOF

sudo chmod +x "$MONITOR_SCRIPT"

# --- Step 2: Create the Launch Daemon plist ---
echo "⚙️ Creating launch daemon at $PLIST_PATH"

cat <<EOF | sudo tee "$PLIST_PATH" > /dev/null
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>$PLIST_NAME</string>
    <key>ProgramArguments</key>
    <array>
        <string>$MONITOR_SCRIPT</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>KeepAlive</key>
    <true/>
</dict>
</plist>
EOF

sudo chown root:wheel "$PLIST_PATH"
sudo chmod 644 "$PLIST_PATH"

# --- Step 3: Load the Launch Daemon ---
echo "🚀 Loading launch daemon..."
sudo launchctl load -w "$PLIST_PATH"

# --- Step 4: Update sudoers for passwordless shutdown ---
echo "🛡️ Updating sudoers to allow passwordless shutdown"

# Backup sudoers file before modifying
echo "📦 Backing up /etc/sudoers to $SUDOERS_BACKUP"
sudo cp /etc/sudoers "$SUDOERS_BACKUP"

SUDOERS_TEMP=$(mktemp)
sudo visudo -cf /etc/sudoers > /dev/null 2>&1
if ! grep -q "/sbin/shutdown" /etc/sudoers; then
  sudo bash -c "echo '%admin ALL=(ALL) NOPASSWD: /sbin/shutdown' >> /etc/sudoers"
  echo "✅ Sudoers updated successfully."
else
  echo "ℹ️ Sudoers already contains shutdown rule. Skipping..."
fi

# --- Final Summary ---
echo ""
echo "✅ USB Killswitch setup complete!"
echo "💡 Unplugging '$DEVICE_NAME' will trigger immediate system shutdown."
echo "🛠️ Monitor script: $MONITOR_SCRIPT"
echo "📄 LaunchDaemon: $PLIST_PATH"
echo "📜 Log file: $LOGFILE"