Block Screen

4 min read Updated Sep 23, 2026

Introduction

The Block Screen is GuacamoleID's primary security feature. When the application detects that you've stepped away or an unauthorized person is in front of your computer, it immediately displays a full-screen overlay that prevents access to your desktop and applications.

How the Block Screen Works

GuacamoleID continuously monitors for your presence using facial recognition. The Block Screen activates when:

  1. You Walk Away: The camera no longer detects your registered face
  2. Intruder Detected: An unregistered face appears in front of the camera
  3. Shoulder Surfing: Someone else is detected looking at your screen (if enabled)
  4. Manual Lock: You manually trigger the block screen
  5. Inactivity Timeout: No activity detected for the configured period

Block Screen Appearance

When activated, the Block Screen:

  • Covers all open applications and the desktop
  • Displays the GuacamoleID logo and status message
  • Shows a live camera preview (optional)
  • Provides a registration button for new users
  • Detects key presses and sends the system to Windows lock screen

Custom Background Image

You can personalize the Block Screen with your own background image:

  1. Go to Settings > Block Screen
  2. Enable Custom Background Image
  3. Click Browse and select your image
  4. The image will be displayed when the screen is blocked

Unblocking the Screen

To unlock and return to your desktop:

  1. Face Recognition: Simply look at the camera - GuacamoleID will recognize you and unlock automatically
  2. Windows Login: If face recognition fails, press any key to be taken to the Windows lock screen where you can use your password

The unlock process is seamless - just position yourself in front of the camera and the screen unblocks within seconds.

Blocking Speed

Configure how quickly the screen blocks after losing recognition:

Speed Description Best For
Slow Longer delay before blocking Casual home use
Medium Balanced response time General office work
Fast Quick blocking Sensitive environments
Very Fast Immediate blocking High-security settings

To change the blocking speed: 1. Go to Settings > Block Screen 2. Select your preferred Blocking Speed 3. Changes take effect immediately

Anti-Spoofing Protection

The Block Screen includes anti-spoofing measures to prevent unauthorized access using photos or videos of authorized users. See the Anti-Spoofing Protection page for detailed information.

Available anti-spoofing levels:

Level Description
Off No anti-spoofing (not recommended)
Passive (Beta) Background analysis without user interaction
Active Requires user interaction for verification
Depth Vision Uses IR depth camera for 3D verification

Registering from the Block Screen

New users can register their face directly from the Block Screen:

  1. When the Block Screen is displayed, click the Register button in the bottom-left corner
  2. Follow the face registration process
  3. Once registered, the screen will unlock

This feature allows new authorized users to gain access without requiring someone to unlock the computer first.

Block Screen Settings

Access all Block Screen settings through Settings > Block Screen:

Display Options

  • Show Camera Preview: Display live camera feed on the block screen
  • Custom Background: Use your own background image
  • Display Time: Show current time on the block screen

Security Options

  • Blocking Speed: How quickly to activate blocking
  • Anti-Spoofing Level: Protection against photo/video attacks
  • Allow Registration: Enable/disable registration from block screen

Behavior Options

  • Key Press Action: What happens when a key is pressed (Windows lock screen)
  • Mouse Action: Response to mouse movement while blocked

Windows Lock Screen Integration

When the Block Screen is active and a key is pressed:

  1. GuacamoleID detects the keypress
  2. The system transitions to the Windows lock screen
  3. This provides an additional layer of security
  4. Users can log in with Windows credentials if face recognition fails

This integration ensures that even if someone bypasses the GuacamoleID block screen, they still face Windows authentication.

Troubleshooting

Block Screen Activates Too Frequently

  • Adjust the Blocking Speed to a slower setting
  • Ensure your face is well-lit and visible to the camera
  • Check camera positioning and angle
  • Consider creating a low-light profile if lighting varies

Block Screen Won't Unblock

  • Ensure adequate lighting on your face
  • Position yourself directly in front of the camera
  • Clean the camera lens
  • Check that your profile is active
  • Press any key to use Windows lock screen as fallback

Block Screen Appears Briefly Then Disappears

  • This indicates momentary loss of recognition
  • Improve lighting conditions
  • Reduce camera obstructions
  • Create profiles for different conditions

Custom Background Not Displaying

  • Verify the image file exists and is accessible
  • Try using a different image format (JPG, PNG)
  • Check that the feature is enabled in settings