What is a Network Port?

Ports are a fundamental aspect of connectivity and data transfer. But what is a network port? Contrary to what many believe, a port isn’t just a physical connection. It’s also a logical connection that programs use to exchange information. In this article, learn what a network port is, which port types exist, how to utilize a port number, and how a port keeps your network connections more efficient.

What is a Network Port?

A network port is a process-specific or an application-specific software construct serving as a communication endpoint, which is used by the Transport Layer protocols of the Internet Protocol suite, such as User Diagram Protocol (UDP) and Transmission Control Protocol (TCP).

A specific network port is identified by its number commonly referred to as a port number, the IP address with which the port is associated, and the type of transport protocol used for the communication.

A port number is a 16-bit unsigned integer that ranges from 0 to 65535.

How does it work?

Generally, ports are a way for your computer to know which program to forward data to when information arrives from the network. For example, if a message arrives on port 443 on a server, the computer knows to forward it to the web server software. But if something arrives on port 21, the computer knows to forward it to the File Transfer Protocol (FTP) server.

Computers don’t open these network connections; programs running on computers do. You won’t typically encounter them directly while browsing the Internet because your operating system and applications handle them seamlessly.

However, understanding ports becomes crucial for troubleshooting network issues or configuring advanced settings like port forwarding. If you have trouble with your port connections, you can use the WhatIsMyIP port scanner tool to assess the status of the ports.

Benefits of Network Port

Network ports offer several key benefits:

• Efficient Communication: By providing designated entry points for data, network ports enable efficient and organized communication between devices.
• Enhanced Security: Port-based communication allows network administrators to implement security measures such as firewalls and access controls, safeguarding against unauthorized access and potential threats.
• Scalability: With the use of ports, networks can easily scale to accommodate growing numbers of devices and services without sacrificing performance or reliability.
• Interoperability: Standardized port numbers facilitate interoperability between different systems and devices, ensuring seamless communication across diverse network environments.

How do they affect cyber security?

Network ports are a major factor in network security and cybersecurity in general.

Port scanning, for example, tries all ports at an address to see which ones are open and listening. Attackers can use this to find vulnerable services that they can then attack.

Firewalls take the port number into consideration when determining whether to allow or block communication. They are configured to only allow communication to the specific ports needed for a service and block other unneeded ports so they cannot be exploited.

As an example of ports in use, say a company wants to have a website, email, and secure file transfer service on the internet. Its firewall would allow inbound connections to ports 80 and 443 for web traffic, port 25 for inbound email, and port 22 for Secure Shell FTP (SFTP). It forwards these ports to the specific servers for each type of service. The firewall will block all other ports.

So, if an employee incorrectly tries to use FTP on port 21 instead of SFTP, it will be blocked. Or, for instance, if an attacker tries to connect to port 3389 for Windows Remote Desktop to gain control of a server, the firewall will block the connection.

Some examples

Network ports are typically divided into three ranges: well-known ports (0-1023), registered ports (1024-49151), and dynamic/private ports (49152-65535). Well-known ports are reserved for use by specific protocols and applications, registered ports are typically used for custom or third-party applications, and dynamic/private ports are available for use by any application.

Here are some of the most common network ports and their associated protocols:

• Port 80: HTTP (Hypertext Transfer Protocol)
• Port 443: HTTPS (Hypertext Transfer Protocol Secure)
• Port 22: SSH (Secure Shell)
• Port 23: Telnet
• Port 25: SMTP ( Simple Mail Transfer Protocol )
• Port 53: DNS (Domain Name System)
• Port 69: TFTP (Trivial File Transfer Protocol)
• Port 8080: HTTP Alternate
• Port 143: IMAP (Internet Message Access Protocol)

Conclusion

I hope it helped you understand what network ports are and their basic functions. As a quick recap, network ports identify a server or protocol and help keep the session between hosts. There are many topics I weeded out just to stay focused on network ports as my goal was to help those wanting to get a better understanding of the concept without going through a complete networking class.