What is a Port?
A port is a virtual endpoint on a network device, such as a computer or server, used to identify specific applications or services. It’s a numerical identifier that allows different applications to communicate simultaneously over the same network connection.
Benefits:
- Multiple connections: Enables multiple applications to use the same network connection.
- Security: Port filtering can be used to restrict network access.
- Service identification: Clearly defines the application or service associated with a connection.
Use Cases:
Ports are fundamental to network communication:
- Web browsing: Port 80 for HTTP, port 443 for HTTPS.
- Email: Port 25 for SMTP, port 110 for POP3, port 993 for IMAP.
- File transfer: Port 21 for FTP.
- Remote access: Port 22 for SSH.
- Online gaming: Various ports depending on the game.
Key Components:
- Port number: A 16-bit number ranging from 0 to 65535.
- Protocol: The communication protocol used (TCP or UDP).
- Socket: The combination of an IP address and a port number.
- Well-known ports: Standardized ports for common services (e.g., 80 for HTTP).
- Registered ports: Assigned to specific organizations or applications.
- Dynamic or private ports: Used for temporary connections.
