The most commonly used ports are the TCP/IP ports, which are used for communication over the Internet. There are many other ports. However, only the common and most used ones are explained in this article.
TCP and UDP Ports
Protocol is a set of instructions that is to be followed. Likewise, there are certain instructions that are to be followed in communication of data over the Internet. Basically, there are two types of protocols used over the Internet, viz., TCP and UDP. TCP stands for transmission control protocol and UDP stands for user datagram protocol. Now, you must be wondering, why are these protocols required in simple communication over the Internet! The answer to this question is that, the communication must be safe, quick, and reliable. In TCP, the data transfer from one computer to another is done directly. To be more precise, the two devices intended to start a conversation connect to each other and start transferring data. These two computers or devices remain connected throughout the period of transfer and get disconnected after the transfer of data is completed. On the other hand, in UDP the data is converted into data packets and are sent over the Internet. There is no direct connection between the two devices intended to communicate. UDP transfer of data does not guarantee a reliable transfer of data. The speed communication in UDP is slower as compared to the TCP.
Every computer and device connected to the Internet has its own IP address. This address is unique to every computer and device. When some information is sent over the Internet, the IP address acts as an address of each of the device. The data is sent with the IP address of the receiver device and it is accepted with the help of TCP or UDP ports. When information is sent over the Internet, it also includes the IP address and the port of the receiver device. These ports are called TCP/IP ports. There are certain ports that are commonly used over the Internet. The IANA (Internet Assigned Numbers Authority) has registered all the TCP/IP port numbers.
Commonly Used Port Numbers
Here is a list that includes all the ports that are used for transferring the information over the Internet.
| Keywords | Protocols Used | Port Number | Description |
| tcpmux | TCP, UDP | 1 | TCP port service multiplexer |
| echo | TCP, UDP | 7 | Echo |
| discard | TCP, UDP | 9 | Discard |
| msp | TCP, UDP | 18 | Message Send Protocol |
| ftp | TCP, UDP | 21 | File transfer protocol |
| ssh | TCP, UDP | 22 | Remote login protocol |
| telnet | TCP, UDP | 23 | Telnet |
| smtp | TCP, UDP | 25 | Simple Mail Transfer Protocol |
| domian | TCP, UDP | 53 | Domain Name Sever |
| www | TCP, UDP | 80 | World Wide Web or also known as HTTP |
| rtelnet | TCP, UDP | 107 | Remote Telnet Services |
| pop 2 | TCP, UDP | 109 | Post Office Protocol 2 |
| pop 3 | TCP, UDP | 110 | Post Office Protocol 3 |
| sftp | TCP, UDP | 115 | Simple File Transfer Protocol |
| snmp | TCP, UDP | 161 | Simple Network Management Protocol |
| bgp | TCP, UDP | 179 | Border Gateway Protocol |
The port numbers used in the data communication do not distinguish the device identity, but are used to specify the service that is to be provided. For example, HTTP is used for web services or FTP for file transfer. Thus, the port indicates the type of service provided.