TCP Encrypted Messaging Server

A lightweight, production-ready TCP server designed for encrypted communication with clients over persistent connections. Built using Node.js and Redis, this server supports chunked message delivery, ACK handling, AES-GCM encryption, and a scalable event loop with heartbeat detection.

Features

• 🔐 AES-256-GCM based encryption
• 🔁 Persistent bi-directional TCP communication
• 🧩 Supports chunked/streamed packets with null-byte delimiter
• 🔂 Retry logic with acknowledgments for event delivery
• 🧵 Handles multiple client connections concurrently
• 💓 Heartbeat detection with ping/pong to track live clients
• 💾 Redis-backed queueing for event and usage tracking
• 🔄 Handles reconnects, client state cleanup
• 🧪 Ready for unit/integration testing
• 🧰 Modular and extensible design

Folder Structure

TCP_CLIENT/
├── client/                 # Minimal client example for testing
├── connections/            # Handles socket-level logic per client
├── crypto/                 # Encryption utilities (e.g., DH, AES)
├── services/               # Redis and other backend services
├── shared/                 # Shared helpers like packet encoder/decoder
├── utils/                  # Logging, configuration, helpers
├── tests/                  # Automated test cases
├── .env                    # Environment configuration (Redis, port, etc.)
├── package.json            # Dependencies and scripts
├── socket-server.js        # Server entrypoint
└── README.md               # This file

Getting Started

Prerequisites

• Node.js >= 18
• Redis >= 6 (with optional password protection)

Installation

git clone https://github.com/joy-acharya/tcp-encrypted-server.git
cd tcp-encrypted-server
npm install
cp .env.example .env

Configuration

Edit the .env file with your Redis settings:

PORT=9000
REDIS_HOST=127.0.0.1
REDIS_PORT=6379
REDIS_PASSWORD=yourpassword

Running the Server

node src/socket-server.js

Testing with Client

Use the provided client simulator to test chunked handshake, reconnections, and heartbeat:

node client/multi-client-simulator.js

API Overview

Client Message Types

• handshake — Initial connection: { type: "handshake", clientId: "101" }
• ack — Acknowledges a server event: { type: "ack", eventId: "evt123" }
• client-event — Sends data from client to server: { type: "client-event", ... }
• pong — Heartbeat response to server's ping

Server Message Types

• server-event — Pushes an event to the client
• ping — Periodic heartbeat check to ensure client is alive

Security

• AES-256-GCM encryption for all payloads
• Each packet includes IV + AuthTag for decryption
• Key derived using Diffie-Hellman + HKDF (planned extension)

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss your idea.

License

MIT

Author

Developed with ❤️ by Joy Acharya