The Most Common Ports in Linux

As a software developer with over ten years of experience, I have worked with Linux, one of the most popular operating systems among developers. One of the key features of Linux is its use of ports, which allow software applications to communicate with each other over a network. In this article, I will explore the most common ports in Linux and their uses.

What Are Ports?

A port is a logical construct that represents a communication endpoint in a network. It allows two applications to communicate with each other over a network by using a specific protocol. Ports are identified by a number, ranging from 0 to 65535. In Linux, there are two types of ports: TCP and UDP.

TCP Ports

TCP (Transmission Control Protocol) is a reliable and connection-oriented protocol that ensures data is delivered in the correct order and without errors. TCP ports are used for applications that require a stable and continuous connection, such as web servers, email servers, and FTP servers.

Port 22 – SSH

One of the most common TCP ports in Linux is port 22, which is used for SSH (Secure Shell) connections. SSH is a secure way to access a remote machine and execute commands. System administrators commonly use it to manage Linux servers remotely. To connect to a remote machine using SSH, you must install an SSH client on your local machine.

If you want to change that port at your convenience, you can follow our tutorial on How to change the SSH server port.

ssh user@hostname

Port 80 – HTTP

Another common TCP port in Linux is port 80, which is used for HTTP (Hypertext Transfer Protocol) connections. HTTP is the protocol used for transferring data over the World Wide Web. When you visit a website, your browser sends an HTTP request to the web server, which responds with the requested data. Port 80 is used by web servers to listen for incoming HTTP requests.

Port 443 – HTTPS

Port 443 is used for HTTPS (HTTP Secure) connections. HTTPS is a secure version of HTTP that encrypts data in transit to prevent eavesdropping and tampering. HTTPS is commonly used for online transactions and other sensitive data transfers. Web servers use port 443 to listen for incoming HTTPS requests.

UDP Ports

UDP (User Datagram Protocol) is a connectionless and unreliable protocol that does not guarantee data delivery or order. UDP ports are used for applications that require high-speed and real-time communication, such as online gaming and streaming media.

Port 53 – DNS

One of the most common UDP ports in Linux is port 53, which is used for DNS (Domain Name System) resolution. DNS is the protocol used for translating human-readable domain names into IP addresses. When you type a URL into your browser, the browser sends a DNS request to a DNS server, which responds with the corresponding IP address. Port 53 is used by DNS servers to listen for incoming DNS requests.

Port 123 – NTP

Another common UDP port in Linux is port 123, which is used for NTP (Network Time Protocol) synchronization. NTP is the protocol used for synchronizing the clocks of computers in a network. It is essential for ensuring that all devices in a network have the same time, which is critical for security and accuracy. Port 123 is used by NTP servers to listen for incoming NTP requests.

Conclusion

Ports are a crucial part of network communication in Linux. They allow applications to communicate with each other over a network by using specific protocols. In this article, we have explored the most common ports in Linux and their uses, including SSH (port 22), HTTP (port 80), HTTPS (port 443), DNS (port 53), and NTP (port 123). Understanding these ports and their functions can help developers and system administrators better manage their networks and ensure that their applications are communicating effectively.

If you want to learn more about ports and their uses in Linux, there are many great resources available online. Two external sources that I recommend for further reading are the Linux Documentation Project’s guide to TCP and UDP ports and the official IANA (Internet Assigned Numbers Authority) port number assignments.

In conclusion, as a software developer who has worked with Linux for many years, I can attest to the importance of understanding ports and their uses in network communication. By familiarizing yourself with the most common ports in Linux, you can improve your ability to manage networks and troubleshoot issues with your applications.

📕 Related articles about Linux

Was this article helpful?

YesNo

The Most Common Ports in Linux

What Are Ports?