Acutis Firewall

A parental control Android app that blocks adult and dangerous content using a local VPN-based DNS filter. Parents can protect settings with a PIN, manage custom blocklists, and set time-based access rules.

Features

Content Blocking

• VPN-based DNS filtering - Intercepts DNS queries locally to block dangerous domains
• No external server required - All filtering happens on-device for privacy
• Works across all apps - Not limited to browsers

Pre-built Blocklists

• Adult content - Blocks pornographic and explicit material
• Malware/Phishing - Protects against known malicious domains
• Gambling - Optional blocking of gambling sites
• Social Media - Optional blocking of social media platforms

Custom Blocklists

• Create custom lists for specific blocking needs
• Add/remove individual domains
• Enable/disable lists independently
• Wildcard support (*.example.com)

Time-Based Rules

• Daily limits - Set maximum usage time per day (e.g., 1 hour of YouTube)
• Scheduled blocking - Block content during specific hours (e.g., bedtime)
• Day-of-week selection - Apply rules only on certain days
• Target selection - Apply rules to domains, categories, or custom lists

PIN Protection

• Secure settings with a 4-digit PIN
• PIN required to disable blocking or modify settings
• Enabling protections does not require PIN (only disabling)

Screenshots

Main Screen	Blocked Sites	Time Rules	Settings
Toggle protection on/off	Manage blocklist categories	Create time-based rules	Configure app settings

Technical Details

Architecture

• Language: Kotlin
• Min SDK: 29 (Android 10)
• Target SDK: 35 (Android 15)
• UI: Jetpack Compose with Material 3
• Database: Room for blocklists and time rules
• Preferences: Encrypted DataStore for PIN storage
• DI: Hilt for dependency injection
• Background: Foreground Service for VPN

How It Works

1. The app creates a local VPN tunnel using Android's VpnService
2. All DNS queries are routed through the VPN
3. Queries for blocked domains return NXDOMAIN (domain not found)
4. Allowed queries are forwarded to upstream DNS (Cloudflare 1.1.1.1)
5. Time rules are evaluated in real-time for dynamic blocking

Building

Prerequisites

• Android Studio Hedgehog or newer
• JDK 17
• Android SDK 35

Build Steps

# Clone the repository
git clone https://github.com/phasnox/acutis_firewall_android.git
cd acutis_firewall_android

# Build debug APK
./gradlew assembleDebug

# Run unit tests
./gradlew testDebugUnitTest

# Run lint checks
./gradlew lintDebug

Testing

# Run all unit tests
./gradlew testDebugUnitTest

# Run specific test class
./gradlew testDebugUnitTest --tests "com.acutis.firewall.viewmodel.HomeViewModelTest"

Permissions

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE_SPECIAL_USE" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

Privacy

• No data collection - All filtering happens locally on your device
• No external servers - DNS queries go directly to Cloudflare (1.1.1.1)
• No analytics - The app does not track usage or behavior
• Encrypted PIN - PIN is stored using Android's EncryptedSharedPreferences

License

This project is licensed under the MIT License - see the LICENSE file for details.