RemoteLAN

A high-performance, custom, LAN-only remote desktop tool for internal office use built with C# / .NET 8 / WPF, designed to work like AnyDesk — every installation can connect out to other machines or accept incoming connections over direct TCP sockets. Zero third-party cloud infrastructure or relay servers required.

• AnyDesk-Style Unified App: Both PC A and PC B install and run the exact same RemoteLAN application.
• Bidirectional Control: Connect from PC A to PC B, or from PC B to PC A, or simultaneously.
• Zero Cloud Relay: Direct TCP socket connections between machines on your trusted local area network.
• Continuous Auto-Discovery & Multi-NIC Deduplication: Automatically discovers active RemoteLAN PCs on your subnet in the background using persistent, stable Machine GUIDs (agent.id). Multi-homed machines (Ethernet + Wi-Fi) are deduplicated into exactly one tile per machine ID, automatically prioritizing wired Ethernet over Wi-Fi with overridable adapter selection.
• System Tray Minimization: Closing the application window (clicking 'X') hides RemoteLAN to the Windows System Tray notification area, keeping the agent server and discovery listening in the background.
• Clean Modern Light Mode UI:
  • Left Vertical Sidebar: Displays This PC's identity, IP address, and alphanumeric session access code with one-click copy, regeneration, and custom code assignment, with a quick-access Settings launcher.
  • Top Horizontal Header: Streamlined remote address input with instant reachability validation before requesting authentication.
  • Interactive Device Grid: Discovered LAN machines shown as square cards with machine name, preferred IP, active connection badge (Ethernet / Wi-Fi), and online badge — click to connect.
• Fast Screen Streaming & Real-Time Lock Screen Control: High-performance DXGI Desktop Duplication engine with automatic GDI fallback and dynamic desktop switching (DesktopManager). Gracefully handles session locks, UAC prompts, and lock screens across session boundaries.
• Windows OS Password Save & Automated Sign-In Screen Unlock: Save remote Windows user passwords per computer. Credentials resolve across stable Machine GUIDs, hostnames, and IP addresses, surviving DHCP changes and multi-NIC adapter transitions. Lock screen unlock employs native Secure Attention Sequence (SendSAS), CapsLock normalization, and hardware scan code synthesis to reliably wake and unlock the Windows logon screen without keystroke drops.
• Persistent Device History & Live Status Indicators: Discovered LAN machines remain saved in device history even when powered down or disconnected. Cards feature real-time status indicators (vibrant green #22C55E when online, slate gray #94A3B8 with card dimming and last-seen timestamp when offline). A 3-dots kebab menu allows configuring OS passwords, forgetting saved credentials, and removing entries from history.
• Automatic Administrator Elevation & Secure Desktop Control: Built-in application manifest and startup elevation routines automatically launch RemoteLAN with Administrator privileges (and seamless transition to SYSTEM token via Winlogon duplication) without requiring manual in-app restart clicks, ensuring full access to the Windows Secure Desktop and sign-in screen.
• Unified Actions Control Center: Consolidated ⚡ Actions ▾ menu in the remote viewer toolbar containing Send Ctrl+Alt+Del, 🔑 OS Login, Send remote input toggle, Lock Remote PC on Session End (off by default), and remote power management (Lock Workstation, Sleep / Suspend, Restart PC..., and Shut Down PC...).
• Interactive Incoming Connection Approval (AnyDesk-Style): When connecting without a saved PIN, the controller PC presents the PIN prompt while concurrently requesting approval in the background. The remote PC displays an incoming connection request dialog with ✓ Accept and ✕ Dismiss buttons. Clicking Accept on the remote PC establishes the session immediately without requiring the controller to enter the access code.
• True Borderless Fullscreen with Peek Toolbar: Fullscreen mode completely expands the remote desktop to fill the screen while hiding toolbars and status bars; hovering near the top edge smoothly reveals the floating peek toolbar.
• Natural Mouse Pointer & Dynamic Resolution: Standard mouse arrow pointer in the remote desktop viewport (eliminating awkward + crosshair cursors), with live dynamic resolution adaptation and aspect-ratio preservation.
• Resilient Input State Management & Bi-directional Input Control: Remote mouse movement, clicks, wheel scrolling, and keyboard keystrokes via Win32 SendInput with letterbox/pillarbox coordinate mapping and scancode keyboard synthesis.
• Modern Rounded App Icon & Full Taskbar Integration: Custom antialiased squircle application icon bundled as multi-resolution .ico (16x16 to 256x256) embedded in the Win32 executable, window taskbar, and installer.
• Dedicated Settings & Security Interface: Comprehensive, modern Light Mode settings window accessible via the ⚙️ Settings button in the left sidebar or system tray context menu:
  • Security PIN Auto-Rotation: Configurable automatic generation of a fresh host PIN after a specified time interval (Never by default, 15m, 30m, 1h, 4h, 8h, 24h). Active sessions remain uninterrupted.
  • Unattended Access Control: Toggle unattended access, configure permanent passwords, and reveal/hide password inputs with dynamic card collapsing.
  • Scrollable & Responsive Content Layout: Smooth vertical scrolling containers across Security, General, and About tabs ensuring zero card cropping regardless of screen resolution or DPI scaling.
  • Unauthorized Access & Brute-Force Protection: Automatic rate-limiting and temporary IP lockout after repeated failed PIN/password attempts, configurable thresholds, lockout durations, and live status countdown.
• About Section & Developer Credentials: Built-in About view providing project details (v1.2.1, GPL-3.0 open source license, technical architecture) and developer credentials (Salman Asmat).
• Semantic Versioning: Adheres strictly to SemVer 2.0.0 (Current version: 1.2.1).

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Architecture

RemoteLAN/
├── RemoteLAN.slnx                    # Solution file
├── src/
│   ├── RemoteLAN/                    # Primary Unified AnyDesk-style Application (Host + Client Viewport)
│   └── RemoteLAN.Protocol/           # Shared wire protocol, framing, messages, discovery models
└── tests/
    └── RemoteLAN.Tests/              # Automated unit, discovery, security, power, input pipeline, and lock recovery test suite (89 tests)

Network Protocols

1. LAN Auto-Discovery (UDP Port 9192)

• Probe: Broadcasts REMOTELAN_DISCOVER_V1 across active local network subnets.
• Response: Replies with REMOTELAN_AGENT_V1|{MachineName}|{TcpPort}|{Version}|{MachineId}|{InterfaceType}|{AdapterIp}.

2. Streaming & Control (TCP Port 9191)

All authentication, desktop video frames, and remote mouse/keyboard inputs multiplex over a single TCP connection:

┌─────────────────┬───────────────────────────────┬──────────────────────────────┐
│ MessageType(1B) │ PayloadLength (4B Big-Endian) │ Payload Bytes (Length bytes) │
└─────────────────┴───────────────────────────────┴──────────────────────────────┘

Message Types

• 0x01 — AuthRequest (PIN verification)
• 0x02 — AuthResponse (Handshake result & remote screen resolution)
• 0x10 — ScreenFrame (JPEG-compressed desktop frame)
• 0x20 — MouseMove (Normalized coordinates 0.0–1.0)
• 0x21 — MouseButton (Left, Right, Middle / Down, Up)
• 0x22 — MouseWheel (Wheel scroll delta)
• 0x30 — KeyboardKey (Virtual Key Code, KeyDown/KeyUp, extended flag)
• 0x35 — SendCtrlAltDel (Remote CAD / wake sign-in screen command)
• 0x36 — PowerAction (Remote system Lock, Sleep, Restart, Shutdown)
• 0x37 — UnlockWithOsPassword (Windows OS lock screen auto-unlock with hardware scan code keystroke injection)

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Quick Start

Prerequisites

• .NET 8.0 SDK or later
• Windows 10/11 or Windows Server

Build

# Build entire solution in Release configuration
dotnet build RemoteLAN.slnx -c Release

Run Tests

# Execute full test suite including bidirectional and discovery tests
dotnet test tests/RemoteLAN.Tests/RemoteLAN.Tests.csproj --verbosity normal

Create Installer (Inno Setup)

To compile and package the standalone Windows installer:

# Execute automated packaging script
.\build-installer.ps1

The compiled installer is output to: dist/RemoteLAN_Setup_v1.2.1.exe

• Fully Self-Contained (.NET 8 Runtime Included): Bundles the complete .NET 8 desktop runtime and CoreCLR libraries directly inside the installer — no separate .NET installation or download required.
• Clean Upgrades: Automatically terminates running processes, cleans old version binaries, and preserves user credentials in %LocalAppData%\RemoteLAN.
• Post-Install Launch Option: Includes an optional checkbox on the final installer page to launch RemoteLAN immediately into the foreground (unchecked by default to preserve silent background startup).
• Automatic Background Startup: Configures Windows Run key (--background) so the host is immediately reachable on boot without displaying the main window.
• Single-Instance Management: Prevents duplicate processes; manual launch signals and brings the active background instance to the foreground.
• System Tray Integration: Closing the window hides to the notification tray; right-click tray icon to open or exit.
• Connection Alert: Main window automatically reveals itself upon incoming remote connection.

Launching RemoteLAN (Works on Any PC)

Run the unified app on both PC A and PC B:

dotnet run --project src/RemoteLAN/RemoteLAN.csproj

How it Works:

1. On PC A:
   • The left sidebar displays PC A's IP address, an alphanumeric session access code (e.g. 7K2M9X), and a Settings button for unattended access and security configuration.
2. On PC B:
   • The left sidebar displays PC B's IP address and its own access credentials.
3. To connect PC A → PC B:
   • On PC A, PC B automatically appears as a square device tile in the discovered devices grid.
   • Click PC B's tile (or enter PC B's IP in the top header and click Connect ➔).
   • RemoteLAN automatically tests reachability. If reachable, it presents the authentication modal with a "Remember password for this device" toggle (or connects instantly if already remembered).
   • Enter PC B's session access code or permanent unattended password and click Connect ➔.
   • A dedicated remote desktop session window opens with full mouse and keyboard control!
4. To connect PC B → PC A:
   • Exact same process in reverse!

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Security

RemoteLAN adheres to strict security standards including constant-time authentication verification (CryptographicOperations.FixedTimeEquals), automated brute-force IP lockouts, command-injection prevention, and isolated memory pipelines for input synthesis and credentials. For complete details, audit findings, supported versions, and vulnerability reporting procedures, see SECURITY.md.