🌐 Protocols & Ports Explained

1. What Are Protocols?

• Definition: Protocols are standardized rules that define how data is transmitted and received across networks.
• Types:
  • TCP (Transmission Control Protocol): Connection‑oriented, ensures reliable delivery.
  • UDP (User Datagram Protocol): Connectionless, faster but less reliable.
  • Other examples: HTTP, HTTPS, FTP, SMTP, DNS, SNMP.
• Role: They act like languages — ensuring both sender and receiver understand each other.

2. What Are Ports?

• Definition: A port is a numeric identifier (0–65535) that specifies which application or service should handle incoming data.
• Analogy: Think of the IP address as a building, and ports as apartment numbers inside that building.
• Categories:
  • Well‑known ports (0–1023): Reserved for standard services.
  • Registered ports (1024–49151): Assigned to user or vendor applications.
  • Dynamic/private ports (49152–65535): Temporary, used for client connections.

3. Common Protocols & Ports

4. How Protocols & Ports Work Together

• When you visit https://example.com:
  • Browser uses HTTPS protocol.
  • Data is sent to port 443 on the server.
  • Server responds using the same protocol and port.
• This ensures the right application (web server) handles the request.

5. Security Considerations

• Open ports can be exploited if services are misconfigured.
• Firewalls control which ports are accessible.
• Best practice: Only keep necessary ports open, and secure protocols (HTTPS, SSH) should replace insecure ones (HTTP, Telnet).

✅ Summary:

• Protocols = rules of communication.
• Ports = numbered endpoints for services.
• Together, they ensure data flows to the correct application securely and efficiently.