What is Port Address?

A port address is a numeric identifier associated with a specific process or service on a computer network. In networking, the term "port" refers to a communication endpoint or a specific process running on a device. Ports are used to distinguish different types of communication services or network processes running on the same device.

Key Points about Port Addresses:

• 16-Bit Number: A port address is represented by a 16-bit unsigned integer, allowing for a total of 65,536 possible port numbers (ranging from 0 to 65,535).
• Well-Known Ports: The Internet Assigned Numbers Authority (IANA) maintains a list of well-known port numbers assigned to specific services. For example, port 80 is commonly associated with HTTP (Hypertext Transfer Protocol), and port 443 is associated with HTTPS (HTTP Secure).
• Dynamic or Private Ports: Port numbers in the range from 49152 to 65535 are typically designated for dynamic or private use. These ports are not assigned to specific services by IANA and can be used by applications as needed.
• Transport Layer: Port addresses operate at the transport layer (Layer 4) of the OSI model. The combination of an IP address and a port number uniquely identifies a process or service on a network.
• Communication Establishment: In networking, when two devices communicate, they establish a connection using a combination of IP addresses and port numbers. This combination is known as a socket.

Example:

In the address "192.168.1.1:80," the IP address is "192.168.1.1," and the port number is "80." This indicates communication with the HTTP service on port 80.

Common Port Numbers:

• Port 20, 21: FTP (File Transfer Protocol)
• Port 22: SSH (Secure Shell)
• Port 25: SMTP (Simple Mail Transfer Protocol)
• Port 53: DNS (Domain Name System)
• Port 80: HTTP (Hypertext Transfer Protocol)
• Port 443: HTTPS (HTTP Secure)
• Port 110: POP3 (Post Office Protocol 3)
• Port 143: IMAP (Internet Message Access Protocol)
• Port 3306: MySQL database

Understanding and managing port addresses is crucial for network administrators, security professionals, and developers, as it plays a fundamental role in enabling communication and ensuring the secure and efficient operation of networked services.

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