Unit-1 Network, Topic: Internet Protocols

Internet protocols: TCP/IP, SMTP, POP3, HTTP, HTTPS.

Remote login and file transfer protocols: SSH, SFTP, FTP, SCP TELNET, SMTP, TCP/IP.

🌐 TCP/IP (Transmission Control Protocol/Internet Protocol)

  • Foundation of the internet and most networks.
  • Defines how data is packetized, addressed, transmitted, routed, and received.
  • Comprises four layers: Application, Transport, Internet, and Network Access.
  • TCP ensures reliable, ordered delivery of data.
  • IP handles addressing and routing of packets.
  • Supports protocols like HTTP, FTP, SMTP.
  • Enables interoperability across diverse systems.
  • Developed by DARPA in the 1970s.
  • Uses IP addresses to identify devices.
  • Highly scalable and platform-independent.

📧 SMTP (Simple Mail Transfer Protocol)

  • Used for sending emails between servers.
  • Operates at the application layer of TCP/IP.
  • Uses port 25 (or 587 for secure transmission).
  • Push protocol: sends emails from client to server.
  • Works with Mail Transfer Agents (MTAs).
  • Cannot retrieve emails—used only for sending.
  • Often paired with POP3 or IMAP for receiving.
  • Supports plain text; MIME extends it for multimedia.
  • Stateless and connection-oriented.
  • Vulnerable to spam unless secured with SMTP Auth.

📥 POP3 (Post Office Protocol v3)

  • Used to retrieve emails from a mail server.
  • Downloads emails to local device and deletes from server.
  • Operates at the application layer.
  • Uses port 110 (or 995 for SSL).
  • Simple protocol, ideal for offline access.
  • Does not support folder synchronization.
  • Messages are stored locally after download.
  • Limited support for multiple device access.
  • Often used in personal email setups.
  • Superseded by IMAP in modern systems.

🌍 HTTP (Hypertext Transfer Protocol)

  • Protocol for transferring web pages and resources.
  • Operates at the application layer.
  • Uses port 80 by default.
  • Stateless and text-based.
  • Supports methods like GET, POST, PUT, DELETE.
  • Client-server model: browser requests, server responds.
  • Used for HTML, CSS, JS, and media files.
  • No encryption—data is sent in plain text.
  • Basis of the World Wide Web.
  • Easily intercepted without HTTPS.

🔒 HTTPS (HTTP Secure)

  • Secure version of HTTP using SSL/TLS.
  • Encrypts data between client and server.
  • Uses port 443.
  • Prevents eavesdropping and tampering.
  • Essential for secure transactions and logins.
  • Provides authentication via digital certificates.
  • Widely adopted across websites.
  • Supports same HTTP methods securely.
  • Improves trust and SEO rankings.
  • Mandatory for modern web applications.

🔐 SSH (Secure Shell)

  • Protocol for secure remote login and command execution.
  • Encrypts all data exchanged.
  • Uses port 22.
  • Replaces insecure protocols like TELNET.
  • Supports password and key-based authentication.
  • Enables tunneling and port forwarding.
  • Used for server administration and automation.
  • Includes tools like scp and sftp.
  • Highly secure and widely supported.
  • Essential for managing Linux/Unix systems remotely.

📂 SFTP (SSH File Transfer Protocol)

  • Secure file transfer protocol built on SSH.
  • Encrypts both commands and data.
  • Uses port 22.
  • Replaces FTP for secure environments.
  • Supports file upload, download, and management.
  • Works in client-server model.
  • Authentication via SSH keys or passwords.
  • Supports GUI and CLI clients (e.g., FileZilla).
  • Ensures data integrity and confidentiality.
  • Ideal for enterprise-grade file transfers.

📁 FTP (File Transfer Protocol)

  • Transfers files between client and server.
  • Uses ports 20 (data) and 21 (control).
  • Operates in active or passive mode.
  • No encryption—data sent in plain text.
  • Supports anonymous login for public access.
  • Commands include GET, PUT, LS, CD.
  • GUI clients available (e.g., WinSCP, FileZilla).
  • Can be secured using FTPS or replaced by SFTP.
  • Useful for bulk file transfers.
  • Less secure without additional encryption.

🖥️ TELNET

  • Protocol for remote login to another computer.
  • Uses port 23.
  • Sends data in plain text—no encryption.
  • Client-server model.
  • Allows command-line access to remote systems.
  • Replaced by SSH due to security concerns.
  • Useful for testing network services.
  • Supports Network Virtual Terminal (NVT).
  • Lightweight and simple.
  • Not recommended for secure environments.

📦 SCP (Secure Copy Protocol)

  • SCP is a secure file transfer protocol based on SSH (Secure Shell).
  • It allows copying files between a local host and a remote host or between two remote hosts.
  • Uses TCP port 22 for encrypted communication.
  • Combines SSH’s encryption with RCP’s file transfer capabilities.
  • Ensures confidentiality and integrity of data during transfer.
  • Supports authentication via passwords or SSH keys.
  • Preserves file attributes like permissions and timestamps.

error: Content is protected !!