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Task

Java-Based Alarm System with Local Email Notification

Overview

This project is a simulated home alarm system built in Java, designed to send email alerts via a local-only SMTP server when triggered. It mimics real-world alarm sensors using keyboard input and operates fully offline — no external internet connectivity required. The system is designed to run on a full Linux system with a permanent network connection, and it uses standard SMTP commands over a raw TCP socket to deliver messages locally.

Key Features

  • Offline Operation
    Uses a local SMTP server (e.g., Postfix) to send email without internet access.

  • Manual Sensor Simulation
    Simulates motion sensors or door sensors through key presses (m for motion, d for door).

  • Email Alert via SMTP
    Manually sends raw SMTP commands over TCP (no external libraries used) to deliver mail.

  • Local Mail Delivery
    Sends messages to the local Linux user’s inbox (/var/mail/username) for verification.

Built From Scratch With:

  • Java Sockets – connects to SMTP server over TCP (port 25)
  • Raw SMTP Protocol Commands – HELO, MAIL FROM, RCPT TO, DATA, QUIT
  • Standard Input (System.in) – listens for specific keypresses to simulate triggers
  • Local Mail Tools – uses mail or mailx to read messages from /var/mail/$USER

How It Works (Step-by-Step)

  1. SMTP Server Setup – Installed and configured Postfix to accept local mail only.
  2. Raw SMTP Socket Programming – Java connects directly to localhost on port 25.
  3. Send Mail via SMTP Commands – Program sends proper SMTP commands to deliver a message.
  4. Receive Email Locally – Local user receives the email; verified using Linux mail tool.
  5. Simulate Alarm Input – Java program waits for specific key presses to simulate an alarm trigger and send alerts.