Stealth Block

Stealth Block is a system-wide content filter that blocks advertisements, trackers, malicious domains, IP addresses, and even entire applications before they can load or run. Unlike browser extensions that only work in one application, Stealth Block protects your entire system - every browser, every app, every connection.

How Stealth Block Works

Stealth Block operates at multiple system levels to provide comprehensive blocking:

• DNS-level blocking - Blocks domains by modifying the Windows hosts file, preventing connections before they start
• Firewall-level blocking - Uses Windows Firewall to block IP addresses and application network access
• Process-level blocking - Monitors and terminates blocked applications before they can run

This multi-layered approach ensures that blocked content cannot bypass protection by using different protocols or methods. Blocked domains simply fail to resolve, blocked IPs cannot be reached, and blocked applications are prevented from running or accessing the network.

Opening Stealth Block

Access Stealth Block from Settings → Tools → Stealth Block, or use the quick access buttons in the Dashboard or footer toolbar. The interface is organized into four main tabs: URLs & Websites, IP Addresses, Applications, and Settings.

Blocking URLs & Websites

The URLs & Websites tab allows you to block specific domains system-wide. When a domain is blocked, all applications on your computer (browsers, apps, games) cannot connect to that domain.

Adding a Blocked URL

1. Open the URLs & Websites tab
2. Enter a domain or URL in the input field (e.g., example.com or https://website.com)
3. Click "Block URL"
4. If Admin Protection is enabled, enter your password when prompted

URL Format:

You can enter URLs in several formats - Stealth Block will automatically parse them:

• example.com - Blocks the domain and all subdomains
• www.example.com - Blocks the specific subdomain
• https://example.com - Protocol is optional and ignored
• http://www.example.com - Both protocol and www are optional

When you block a domain, it's added to your Windows hosts file, redirecting all connections to that domain to localhost (127.0.0.1), effectively blocking them.

Managing Blocked URLs

Each blocked URL appears in the list with:

• The domain name
• The date it was added
• A Remove button to unblock it

Click the Remove button (trash icon) next to any URL to unblock it. Changes take effect immediately.

Use Cases for URL Blocking

• Block malicious or phishing websites
• Prevent applications from connecting to tracking servers
• Block unwanted content or services
• Create a custom blocklist for specific domains

Blocking IP Addresses

The IP Addresses tab allows you to block network connections to specific IP addresses using Windows Firewall rules. This is useful when you know the IP address of a malicious server or want to block connections to specific network endpoints.

Adding a Blocked IP

1. Open the IP Addresses tab
2. Enter a valid IPv4 address (e.g., 192.168.1.1)
3. Click "Block IP"
4. If Admin Protection is enabled, enter your password when prompted

IP Format:

Enter a valid IPv4 address in standard format (e.g., 192.168.1.1). Stealth Block validates the IP address format before adding it to the block list.

When you block an IP address, Stealth Block creates a Windows Firewall rule that blocks all outbound connections to that IP address. This prevents any application on your system from connecting to that IP.

Managing Blocked IPs

Each blocked IP appears in the list with:

• The IP address
• The date it was added
• A Remove button to unblock it

Click the Remove button to unblock an IP address. The firewall rule is automatically removed.

Use Cases for IP Blocking

• Block known malicious IP addresses
• Prevent connections to specific servers
• Block IPs identified in security reports
• Create network-level restrictions

Blocking Applications

The Applications tab allows you to block Windows applications in two different ways: blocking their network access, or completely preventing them from running. This is one of Stealth Block's most powerful features.

Adding an Application to Block

1. Open the Applications tab
2. Click the "Browse" button
3. Navigate to and select the application's executable file (.exe)
4. Click "Add App"
5. If Admin Protection is enabled, enter your password when prompted

After adding an application, it appears in the list with two toggle switches that control how it's blocked.

Application Blocking Modes

Each blocked application has two independent blocking options:

Important Notes:

• You can enable either blocking mode, but not both simultaneously. Enabling one automatically disables the other.
• When "Block Completely" is enabled, Stealth Block monitors your running processes every 10 seconds and automatically terminates any instances of blocked applications.
• When a completely blocked application is detected, a modal notification appears showing the application name and explaining that it has been blocked.
• Blocked applications are terminated immediately - they cannot run even if launched from different locations or with different names (as long as the executable path matches).

How Complete Blocking Works

When you enable "Block Completely" for an application, Stealth Block:

1. Starts a background process monitor that checks running processes every 10 seconds
2. Compares running process names against your blocked applications list
3. Automatically terminates any matching processes using Windows taskkill
4. Displays a notification modal informing you that the application was blocked

The process monitoring is optimized to run efficiently without impacting system performance. It only activates when you have at least one application with "Block Completely" enabled.

Application Blocked Notification

When a completely blocked application attempts to run, Stealth Block displays a full-screen modal notification that:

• Shows the name of the blocked application
• Explains that the application has been terminated
• Indicates it was blocked based on your security settings
• Provides an "OK" button to dismiss the notification

This notification ensures you're always aware when a blocked application attempts to run, providing transparency about Stealth Block's actions.

Managing Blocked Applications

Each blocked application in the list shows:

• The application name (extracted from the executable filename)
• The full path to the executable file
• Two toggle switches for "Block Network" and "Block Completely"
• A Remove button to remove the application from the block list

Toggle the switches to enable or disable blocking modes. Changes take effect immediately. When you disable "Block Completely," the process monitoring stops checking for that application. When you disable "Block Network," the firewall rule is removed.

Use Cases for Application Blocking

Block Network Access:

• Prevent applications from "calling home" or sending telemetry
• Allow local functionality while blocking internet access
• Stop applications from downloading updates or content
• Prevent data exfiltration from specific applications

Block Completely:

• Prevent unwanted software from running entirely
• Block applications that cannot be uninstalled normally
• Enforce security policies on shared computers
• Prevent children or other users from running specific applications
• Block malware or suspicious applications

Adblock Feature

Stealth Block includes a system-wide adblock feature that blocks advertisements, trackers, and malicious domains using predefined blocklists. This feature works at the DNS level, blocking domains before connections are even attempted.

Enabling Adblock

1. Open the Settings tab in Stealth Block
2. Find the "Adblock" section (marked as BETA)
3. Toggle the Adblock switch to On
4. Choose the adblock mode that fits your needs (see Adblock Modes below)
5. If Admin Protection is enabled, enter your password when prompted

When enabled, Stealth Block loads domains from predefined blocklist files and adds them to your hosts file, blocking them system-wide. The blocklists are continuously updated and include thousands of known ad networks, tracking domains, and malicious sites.

Adblock Modes

Stealth Block's adblock has two intensity levels you can pick from:

Switching Modes. When you enable adblock, choose the mode that fits your tolerance for false positives. You can switch modes at any time - Stealth removes the previous mode's domains and applies the new mode's list.

DNS Cache Flush. After applying either mode, Stealth automatically flushes the DNS cache so changes take effect immediately.

Viewing Blocked Domains

After enabling Adblock, you can view all blocked domains:

1. In the Adblock section, click "Show Domains"
2. The domain management interface appears
3. You'll see the "Blocked Domains" tab showing all domains currently blocked by adblock

The blocked domains list can contain thousands of entries. Use the search box to find specific domains. The list uses virtual scrolling for performance, so it can handle large numbers of domains efficiently.

Domain Search

The search feature allows you to quickly find domains in the blocked list:

• Type any part of a domain name in the search box
• Results filter in real-time as you type
• The search shows how many domains match your query
• When you have search results, a "Safelist All Results" button appears to quickly safelist all matching domains

The Safelist

The safelist allows you to exempt specific domains from adblock blocking. Domains in the safelist will always be allowed, even if they appear in the blocklists.

Adding Domains to Safelist:

1. Click the "Safelist" tab in the domain management interface
2. Enter a domain name in the input field (e.g., teams.microsoft.com)
3. Click "Add to Safelist"

You can also add domains directly from the blocked domains list:

1. Find the domain in the "Blocked Domains" tab (use search if needed)
2. Click the "Safelist" button next to the domain
3. The domain is immediately moved to the safelist

Bulk Safelisting:

When you have search results showing, you can safelist all matching domains at once:

1. Enter a search query that matches the domains you want to safelist
2. Click "Safelist All Results" button
3. All matching domains are added to the safelist immediately

Removing from Safelist:

To remove a domain from the safelist:

1. Go to the "Safelist" tab
2. Find the domain in the list
3. Click the "Remove" button next to it

Automatic Safelisting:

Stealth Block automatically safelists essential domains to ensure system functionality:

• FVTAL domains - All FVTAL and Stealth-related domains are automatically safelisted and cannot be removed. This ensures Stealth authentication, updates, and core functionality always work.
• Microsoft domains - Microsoft, Office, Outlook, and related domains are automatically safelisted to ensure Windows and Office functionality.

These essential domains appear in the safelist with badges indicating their importance. FVTAL domains cannot be removed - attempting to do so will show an error message.

Adblock Statistics

The Adblock section displays:

• Total number of blocked domains (shown in the "Blocked domains" count)
• Total number of safelisted domains (shown in the "Safelisted domains" count)
• Real-time blocking statistics during your session

The domain lists are resizable - you can drag the resize handle to adjust the height of the domain list display for better visibility.

Recovery & Cleanup

Adblock writes to a marked section of your Windows hosts file (# STEALTH ADBLOCK START / # STEALTH ADBLOCK END). If Stealth crashes or is force-killed mid-update, that section can be left in a dirty state. Stealth Block detects this on startup and offers automatic recovery, with manual fallbacks:

Settings & Configuration

Admin Protection

Admin Protection adds a password requirement for modifying blocked items. This is useful for:

• Preventing unauthorized changes on shared computers
• Protecting your block list from accidental modifications
• Enforcing security policies in managed environments

Enabling Admin Protection:

1. Go to the Settings tab
2. Find the "Admin Protection" section
3. Toggle the Admin Protection switch to On
4. Enter a password (minimum 4 characters) in both password fields
5. Click "Set Password"

Once enabled, you'll be prompted for your password whenever you:

• Add a URL, IP, or application to the block list
• Remove a blocked item
• Toggle application blocking modes
• Enable or disable adblock
• Modify safelist entries

Managing Admin Protection:

• Change Password - Click "Change Password" to set a new admin password
• Remove Password - Click "Remove Password" to disable Admin Protection entirely

If you forget your admin password, you can disable Admin Protection by removing the password, which requires entering the current password. If you've truly forgotten it, you may need to reset Stealth Block settings.

System Status

The System Status section shows the current operational state of Stealth Block's blocking mechanisms:

If either status shows as inactive (red), Stealth Block cannot use that blocking method. This typically means:

• Stealth is not running with administrator privileges
• Windows Firewall is disabled or restricted
• System permissions are preventing access

Run Stealth as administrator to ensure full functionality.

Session Management

The Session Management section displays:

• Session Active - Whether Stealth Block is currently active and monitoring
• Total Active Blocks - The total number of items currently blocked (URLs + IPs + Applications)

This gives you a quick overview of how many items are currently being blocked by Stealth Block.

Management Actions

The Management Actions section provides system-wide controls:

Status Bar

The status bar at the top of Stealth Block shows:

• System Status - Overall operational status (Active/Inactive) with a colored indicator
• Total Blocked Count - Total number of items currently blocked (URLs + IPs + Applications)
• Admin Protection Status - Shows "Admin Protection Enabled" when password protection is active

The status indicators update in real-time as you add or remove blocked items.

If the marker block in the hosts file is missing, malformed, or duplicated, the System Status indicator will turn yellow and a warning appears. Use Refresh Status or Emergency Adblock Cleanup to repair.

How Blocking Persists

Stealth Block's blocking rules persist across application restarts:

• URL blocks - Stored in the Windows hosts file, which persists until manually removed
• IP blocks - Windows Firewall rules persist until removed
• Application blocks - Firewall rules and process monitoring settings are saved and restored on startup
• Adblock - Blocked domains remain in the hosts file until adblock is disabled

When you close Stealth, blocking rules remain active. When you restart Stealth, it automatically restores all your blocking rules and resumes monitoring.

Troubleshooting

Blocked Website Not Working

If a legitimate website doesn't work after enabling adblock or blocking URLs:

1. Check if the domain is in your blocked URLs list
2. If using adblock, check if the domain appears in the blocked domains list
3. Add the domain to your safelist (Settings tab → Adblock section → Safelist tab)
4. Clear your browser cache and restart the browser

Application Still Running When Blocked

If an application with "Block Completely" enabled is still running:

1. Verify the toggle is actually enabled (should show as active/on)
2. Check that the application path in the list matches the actual executable path
3. Manually close the application - Stealth Block monitors every 10 seconds, so there may be a brief delay
4. Ensure Stealth Block is running (check system tray)
5. Try disabling and re-enabling "Block Completely" for that application

Can't Add or Remove Items

If you're unable to add or remove blocked items:

1. Check if Admin Protection is enabled - you'll need to enter your password
2. Verify system status indicators show green (active) for hosts file and firewall access
3. Ensure Stealth is running with administrator privileges
4. Try clicking "Refresh Status" in the Settings tab

Adblock Breaking Websites

If adblock is causing issues with legitimate websites:

1. Add the problematic domain to your safelist
2. If many sites are breaking, you may need to add multiple domains to the safelist
3. Use the search feature to find and safelist related domains (e.g., if example.com breaks, you may need to safelist example.com, www.example.com, api.example.com, etc.)
4. If issues persist, temporarily disable adblock to verify it's the cause

Best Practices

Start Conservative: Begin with URL and IP blocking before using application blocking. Application blocking is more aggressive and can prevent legitimate software from functioning.

Use Safelist Proactively: When enabling adblock, be prepared to add domains to your safelist. Many legitimate services use domains that may be blocked by default blocklists.

Test Before Blocking Completely: Before enabling "Block Completely" for an application, consider testing with "Block Network" first to ensure you don't need the application for local functionality.

Regular Review: Periodically review your blocked items list. Remove items you no longer need to block to keep your configuration clean and maintainable.

Backup Configuration: Use the "Export Blocks" feature to save your configuration before making major changes or before reinstalling Stealth.

Admin Protection: Enable Admin Protection on shared computers or when you want to prevent accidental changes to your blocking rules.

Technical Details

URL Blocking Implementation: URLs are blocked by adding entries to the Windows hosts file (C:\Windows\System32\drivers\etc\hosts). Each blocked domain is redirected to 127.0.0.1 (localhost), preventing DNS resolution and connection.

IP Blocking Implementation: IP addresses are blocked using Windows Firewall outbound rules. Stealth Block creates firewall rules that block all outbound traffic to specified IP addresses.

Application Network Blocking: Uses Windows Firewall to create application-specific rules that block all network traffic from the specified executable.

Application Complete Blocking: Uses process monitoring (tasklist) to detect when blocked applications start, then terminates them using taskkill. Monitoring runs every 10 seconds to balance responsiveness with system performance.

Adblock Implementation: Loads domains from predefined blocklist files and adds them to the hosts file. Blocklists are processed to extract domain names from various formats (hosts file format, plain domain lists, etc.).

All blocking operations require appropriate Windows permissions. Stealth Block will prompt for administrator elevation when needed, or you can run Stealth as administrator for seamless operation.