14 common network ports you should know

14 common network ports you should know

Here are some of the most often-encountered network ports and their associated services.

14 common network ports you should know
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The physical ports on your computer allow communicate with peripheral devices such as your keyboard and mouse and to connect with internet devices via Ethernet cables.

Witin computer networking, ports serve a similar purpose. When a computer system seeks to connect to another computer, the port serves as a communication endpoint. It is also possible for different services running on the same computer to expose various ports and communicate with one another using these ports. In simple terms, if a software application or service needs to communicate with others, it will expose a port. Ports are identified with positive 16-bit unsigned integers, ranging from 0 to 65535. Other services use this port number to communicate with the service or app. Port numbers are divided into three ranges: well-known ports, registered ports, and dynamic or private ports.

Well-known ports (also known as system ports) are numbered from 0 through 1023. For example, to connect to the host example.com via SSH, I would use this command:

ssh username@example.com -v

In this example, -v stands for verbose, and you should see output similar to this:

debug1: Connecting to example.com [<IP Addr>] port 22

As shown, SSH is trying to connect to example.com using port number 22. You may use the -p option to specify another port number; otherwise, SSH will default to 22.

The Internet Assigned Numbers Authority (IANA) has assigned port numbers to commonly used services like SSH, FTP, HTTP, HTTPS, and others. Here are some of the most common ones:

Port Number

Usage

20

File Transfer Protocol (FTP) Data Transfer

21

File Transfer Protocol (FTP) Command Control

22

Secure Shell (SSH)

23

Telnet - Remote login service, unencrypted text messages

25

Simple Mail Transfer Protocol (SMTP) E-mail Routing

53

Domain Name System (DNS) service

80

Hypertext Transfer Protocol (HTTP) used in World Wide Web

110

Post Office Protocol (POP3) used by e-mail clients to retrieve e-mail from a server

119

Network News Transfer Protocol (NNTP)

123

Network Time Protocol (NTP)

143

Internet Message Access Protocol (IMAP) Management of Digital Mail

161

Simple Network Management Protocol (SNMP)

194

Internet Relay Chat (IRC)

443

HTTP Secure (HTTPS) HTTP over TLS/SSL

 

In my work, I most commonly come across ports 80, 443, 20, 21, 22, 23, 25, and 53. Knowing these ports can help you work more efficiently.

What ports do you use the most, and why?

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About the author

Kedar Vijay Kulkarni - I am a Software Quality Engineer at Red Hat working with CloudForms(upstream ManageIQ) project and primarily looking at integration of Ansible with CloudForms and Remote Consoles for various Cloud/Infrastructure Providers. In my free time I try to Travel, watch interesting videos, learn about new technologies.