🌐 “LANComms-LANTP”

A LAN-based chat system with authentication, admin moderation, and a custom transport protocol.

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📖 Overview

LANTP Chat Server is a multi-user chat system built over a custom application protocol (LANTP/1.0) using raw TCP sockets in Python. It supports authenticated logins, real-time messaging, and admin moderation tools, all running on a local network — no external dependencies.

This project was developed as part of a Computer Networks (CN) course to demonstrate low-level socket programming, protocol design, and session management.

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🚀 Key Features

• 🔐 User Authentication

  • Signup and admin approval flow
  • Passwords hashed with SHA-256

• 🧩 Custom Protocol – LANTP/1.0

  • Structured text-based packets
  • Types: SYS, MSG, AUTH_OK, AUTH_FAIL, CMD_RESP, PING, PONG

• 💬 Global & Private Messaging

  • Global chat visible to all users
  • Private DMs via @username

• ⚙️ Admin Controls

  • /kick, /mute, /unmute, /unban, /whois, /announce

• 🧱 Threaded Server Architecture

  • Concurrent client handling
  • Real-time broadcast updates

• 📡 Heartbeat (PING/PONG)

  • Detects disconnected or frozen clients

• 🗃️ Persistent Storage

  • JSON-based user database, pending signups, and chat logs

• 🪶 Lightweight & Pure Python

  • No frameworks, no dependencies

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⚙️ Folder Structure

LANTP_Chat_Server/
│
├── server/
│   ├── server.py         # main server logic (LANTP + commands)
│   ├── server_data/      # config, user data, pending signups
│   └── logs/             # daily log files
│
├── client/
│   └── client.py         # terminal-based LANTP client
│
├── README.md
│
└── LANTP_SPEC.md

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🧩 LANTP/1.0 – LAN Transmission Protocol

A minimal, human-readable text protocol that structures all communication between the client and server.

📦 Packet Format

LANTP/1.0
TYPE: MSG
FROM: test_user
TO: (optional)
CONTENT: Hello, this is a test message!
<END>

🔗 See LANTP_SPEC.md for full protocol documentation.

🔍 Supported Message Types

Type	Direction	Description
SYS	Server → Client	System messages, joins, leaves, or notices
MSG	Both	Normal chat messages
AUTH_OK	Server → Client	Login success confirmation
AUTH_FAIL	Server → Client	Authentication failure
CMD_RESP	Server → Client	Response to a user command (/help, /users)
PING/PONG	Both	Heartbeat keepalive messages
ERR	Server → Client	Protocol or logic errors

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💻 Command Reference

Command	Description	Role
/help	Show list of available commands	All
/users	List all currently online users	All
@username <msg>	Send a private message	All
/kick <user> [reason]	Disconnect user and apply temporary ban	Admin
/mute <user> [minutes]	Mute user temporarily	Admin
/unmute <user>	Unmute user	Admin
/unban <user>	Remove ban early	Admin
/whois <user>	Get info: IP, role, uptime	Admin
/announce <msg>	Broadcast a server-wide announcement	Admin
exit	Disconnect from the chat	All

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🧠 Example Interaction

Client

> LOGIN alex password123
✅ Authenticated. You can now chat! Type /help for commands.

> /users
👥 Online users:
  - alex
  - root [Admin]

> @root Hello admin!
[PM → root]: Hello admin!

Server

🚀 LANTP/1.0 Server running on port 5555
[Admin Action] root muted alex for 5m
[Admin Action] root kicked user1 (Reason: spam)
[TIMEOUT] user2 disconnected (no PONG in 90s)

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🧰 Setup Instructions

Requirements

• Python 3.10 or later
• Local network or localhost setup

Server Setup

cd server
python server.py

• On first launch, you’ll be asked to create an admin account and set a port.
• All data will be stored inside server_data/.

Client Setup

cd client
python client.py

• Enter the server’s IP and port.
• Use SIGNUP <user> <pass> to request registration.
• The admin must approve your signup before LOGIN works.

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🧾 Logging

• All system events (logins, commands, disconnects, timeouts) are saved in:

  server/logs/YYYY-MM-DD.log
  

• Example entry:

  [12:45:22] root (admin) logged in from 127.0.0.1:52341
  [12:47:10] [ADMIN] root muted alex for 2m
  [12:48:33] alex: test message
  [12:52:14] alex (user) disconnected
  

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🧱 Technical Summary

Layer	Technology
Language	Python 3
Transport	TCP (socket module)
Architecture	Multi-threaded server / client
Protocol	LANTP/1.0 (custom text-based)
Data Storage	JSON
Logs	Per-day text logs

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🧩 Future Work

• 🔄 Persistent session recovery after disconnect
• 🔒 TLS or local encryption for passwords
• 💾 Optional SQLite backend for user data
• 🪟 GUI client (Tkinter/PyQt)
• 📡 LANTP/2.0 draft — structured key–value framing with checksums

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👥 Author

Developed independantly by Bashar Mohammad Wakil (24BCE1964) as part of a Computer Networks B.Tech project (VIT)