Ports allow computers to send and receive data over a network and facilitate communication between different applications or devices.
Ports are typically associated with the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), which are two fundamental protocols in computer networking. Each of these protocols has its own set of ports. TCP is used for reliable, connection-oriented communication, while UDP is used for connectionless, unreliable communication.
Ports are identified by numbers ranging from 0 to 65535. They are divided into three ranges:
Well-known ports (0 to 1023): These ports are reserved for specific services or applications, such as HTTP (port 80), HTTPS (port 443), FTP (port 21), SSH (port 22), and more. They are standardized and commonly used for widely known services.
Registered ports (1024 to 49151): These ports are used by various applications and services, but they are not as well-known or standardized as the well-known ports. They are typically assigned by the Internet Assigned Numbers Authority (IANA) upon request.
Dynamic or private ports (49152 to 65535): These ports are available for dynamic allocation by applications and services. They are used for temporary purposes and are not assigned to any specific application or service.
When a computer wants to communicate with a specific service on another computer, it needs to know the IP address of the destination machine and the port number associated with the service it wants to access. Together, the IP address and port number create a unique address, allowing the data to reach the correct application or service on the target device.
| Port Number | Name | Service |
| Port 20 | ftp-data | File Transfer Protocol data |
| Port 21 | ftp | File Transfer protocol port |
| Port 22 | ssh | Secure Shell service |
| Port 23 | telnet | The telnet service |
| Port 25 | smtp | Simple Mail transfer Protocol |
| Port 49 | tactacs | Terminal Access Controller |
| Port 53 | domain | DNS |
| Port 69 | tftp | Trivial File Transfer Protocol |
| Port 80 | http | Hyper Text Transfer Protocol |
| Port 88 | kerberos | Kerberos Authentication |
| Port 110 | pop3 | Post Office Protocol Version 3 |
| Port 119 | nntp | Network News Transfer Protocol |
| port 123 | ntp | Network Time Protocol |
| Port 137 | netbios | NETBIOS Name Service |
| Port 143 | imap | Internet Message Access Protocol |
| Port 161 | snmp | Simple Network Managment |
| Port 162 | snmtrap | Traps for SNMP |
| Port. 389 | ldap | Lightweight Directory Access Protocol |
| Port 443 | https | Secure Hypertext Transfer Protocol |
| Port 444 | snpp | Simple Network Paging Protocol |
| Port 445 | microsoft | Server Message Block |
| Port 500 | isakmp | Internet Key Exchange |
| Port 514 | syslog | UNIX System Logging Service |
| Port 636 | idaps | Secure LDAP |
| Port 1433 | ms-sql-s | Microsoft SQL Server |
| Port 1512 | wins | Microsoft Internet Name Server |
| Port 1701 | l2tp | Layer 2 Tunneling Protocol |
| Port 1723 | PPTP | Point to Point Transfer Protocol |
| Port 1812 | radius | Radius Authentication & Accounting |
| Port 3389 | rdp | Remote Desktop Protocol |