The Internet Assigned Numbers Authority (IANA) maintains a list of well-known ports that are standardized for specific types of network services and communication protocols. These ports help ensure that data is properly routed to the appropriate service or application running on a computer or network device. When you reach an IP address, a port is used which allows access to a protocol. If the port is closed or blocked by a firewall, then that port/protocol will be inaccessable through the network. Here are some common ports.
1. Port 20 and Port 21: FTP (File Transfer Protocol)
- Port 20: Used for FTP data transfer (active mode).
- Port 21: Used for FTP control commands, authentication, and initial connection setup.
2. Port 22: SSH (Secure Shell)
- Used for secure remote administration and encrypted file transfers.
3. Port 23: Telnet
- Telnet is an older, insecure protocol used for remote command-line access to network devices.
4. Port 25: SMTP (Simple Mail Transfer Protocol)
- Used for sending email messages between email servers.
5. Port 53: DNS (Domain Name System)
- Used for translating human-readable domain names into IP addresses and vice versa.
6. Port 80: HTTP (Hypertext Transfer Protocol)
- Used for unencrypted web browsing and data transfer.
7. Port 443: HTTPS (Hypertext Transfer Protocol Secure)
- Used for secure, encrypted web browsing and data transfer, such as online banking or e-commerce.
8. Port 110: POP3 (Post Office Protocol version 3)
- Used for receiving email from a mail server.
9. Port 143: IMAP (Internet Message Access Protocol)
- Used for retrieving email messages from a mail server, often with more advanced features than POP3.
10. Port 3389: RDP (Remote Desktop Protocol) – Used for remote desktop and screen sharing on Windows-based systems.
11. Port 443: SNMP (Simple Network Management Protocol) – Used for monitoring and managing network devices and services.
12. Port 3306: MySQL – Used for communication with MySQL database servers.
13. Port 5432: PostgreSQL – Used for communication with PostgreSQL database servers.
14. Port 22: SFTP (SSH File Transfer Protocol) – Used for secure file transfer over SSH connections.
15. Port 119: NNTP (Network News Transfer Protocol) – Used for retrieving newsgroup messages from Usenet servers.
16. Port 5060: SIP (Session Initiation Protocol) – Used for managing voice and video calls over the internet, commonly used in VoIP services.
17. Port 67 and Port 68: DHCP (Dynamic Host Configuration Protocol) – Port 67: Used by DHCP servers to offer configuration settings to client devices. – Port 68: Used by DHCP clients to request and receive configuration settings from DHCP servers.
18. Port 69: TFTP (Trivial File Transfer Protocol) – Used for simple, lightweight file transfers, often in network booting or firmware updates.
Network administrators and security professionals often use this port information to configure firewalls, routers, and other network devices to control access and ensure the proper functioning of network services.
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