🖧 Decentralized LAN Communication Suite

Peer-to-Peer Chat • Video Calls • File Transfer • Distributed Drive • (Optional) SMTP Mail
A CCN-based communication platform running entirely on a LAN environment.

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🚀 Overview

This project is a fully decentralized communication system built using Computer Communication Networks (CCN) concepts.
Instead of routing communication through heavy centralized servers, devices inside a Local Area Network (LAN) communicate directly using P2P connections.

Think of it as a simplified combination of:

• 🟢 WhatsApp → Messaging
• 🔵 Zoom → Video/Audio Calls
• 🟣 AirDrop → File Transfer
• 🟠 Google Drive → Shared Distributed Storage
• 🟡 Gmail → Optional SMTP Mail Integration

But everything runs peer-to-peer — private, fast, and independent of the internet.

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🧱 Features

1️⃣ Real-Time Chat (P2P)

• One-to-one and group chat.
• Messages sent over WebRTC Data Channels → direct device-to-device.
• Zero message storage on the server.
• Automatic fallback via Socket.IO when WebRTC channels fail.

2️⃣ Video & Audio Calls (Mini Zoom)

• Real-time media streaming using WebRTC.
• Direct encrypted P2P transmission.
• Multi-peer meeting rooms with signaling server coordination.
• Low latency since media does not pass through backend.

3️⃣ Fast File Transfer (AirDrop-like)

• Large files split into chunks.
• Chunks transferred via WebRTC Data Channels.
• Receiver reassembles the file in sequence.
• Encryption before sending.
• Real-time progress UI.
• Fallback server upload/download if P2P breaks.

4️⃣ Distributed Shared Drive (P2P Google Drive)

• Files encrypted → split into fragments → stored across multiple peers.
• Backend holds metadata mapping fragments to peer devices.
• Redundant fragments ensure availability even when peers go offline.
• Enables a private, self-controlled cloud drive experience inside a LAN.

5️⃣ Optional SMTP Email Integration

• Basic email sending using NodeMailer (SMTP).
• Shows integration of classic communication with P2P architecture.

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🏗 System Architecture

🔹 Hybrid Client–Server + Peer-to-Peer Model

The backend server performs only:

• Peer discovery
• Room management
• Forwarding WebRTC signaling messages (SDP offer/answer + ICE candidates)
• Distributed storage metadata management

📌 Actual chat, calls, and file data never go to the server.
All real communication is direct P2P.

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🛠 Tech Stack

Frontend

• React.js
• Vite
• WebRTC (Media Streams + Data Channels)

Backend

• Node.js
• Express.js
• Socket.IO
• Metadata storage utilities
• File chunking + encryption utilities

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🔄 WebRTC Connection Flow

1. Peer A joins a room and creates an SDP Offer
2. Offer is sent to Peer B through the signaling server
3. Peer B responds with an SDP Answer
4. Both peers exchange ICE Candidates
5. Direct encrypted P2P channel established
6. Chat, calls, files flow directly between peers

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📁 File Transfer Process

• File is divided into small chunks
• Chunks are streamed over WebRTC DataChannel
• Receiver reassembles them in order
• Encryption ensures privacy
• Real-time progress tracking
• Server fallback for failure recovery

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☁️ Distributed Storage Workflow

1. File encrypted
2. File split into fragments
3. Fragments distributed across multiple peer devices
4. Backend stores mapping:

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▶️ Running the Project

Backend

cd backend
npm install
node server.js

Frontend

cd frontend
npm install
npm run dev