Port Number in Networking

What are port numbers? Are port numbers unique when the data is trasmitted from sender to receiver or vice-versa? How are they different from protocol number?

Every service needs a identity on Internet. Each Port number represents a service like http, ftp, telnet.

Port numbers are categorised into three ranges:


  1. Well-known ports (0-1023): These ports are reserved for commonly used services, and their assignments are standardized by the Internet Assigned Numbers Authority (IANA). Some well-known port examples include:
  • Port 80: HTTP (Hypertext Transfer Protocol)
  • Port 443: HTTPS (HTTP Secure)
  • Port 21: FTP (File Transfer Protocol)
  • Port 22: SSH (Secure Shell)
  • Port 25: SMTP (Simple Mail Transfer Protocol)
  1. Registered ports (1024-49151): Registered ports are often used by applications and services developed by organizations or software vendors. You can buy these from IANA if you are a company which needs a Port Number.

  2. Dynamic or private ports (49152-65535): These ports dynamically assigned by the operating system when initiating a network connection.

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