What are Ports in Networking

When you ask for a website from the web server, how does it distinguish your device from your colleague’s when both are connected to the same Wi-Fi network? This is possible because of the Ports in networking. Network ports are different from USB ports, Ethernet ports, or HDMI ports. Network ports are not visible and have no physical appearance. In this article, we will learn about ports in networking, also known as virtual ports or network ports, how they work, and their importance. We will also briefly look at their role in cybersecurity.

• What Are Ports?
• What Are Network Ports?
• Why Are Network Ports Called “Virtual Ports”?
• How Do Network Ports Work?
• What Is the Importance of a Network Port?
• Categorizing Port Numbers: Well-Known, Registered, and Dynamic
• Difference Between TCP and UDP Ports
• Network Ports and Cybersecurity: Protecting Your Digital Gateways
• Conclusion

What are Ports?

Ports are communication endpoints that allow communication between different devices and their applications, enabling data exchange. They can be physical ports and virtual ports. Virtual ports are also known as network ports.

1. Physical Ports

Physical ports in a computer serve as the hardware interface, used to directly connect hardware devices to the local device. For example:

• USB ports – for keyboards or flash drives
• HDMI ports – for monitors and projectors
• Ethernet ports – for wired internet connections

2. Network Ports or Virtual Ports

Network Ports are used to establish communication between applications on different devices. They are also used to identify specific processes or services on a device.

• Port 80 – It is used for HTTP web traffic.
• Port 22 – It is used for SSH (Secure Shell) connections.

Let us look at network ports in detail.

What are Network Ports?

As discussed previously, Network ports, also known as virtual ports, are used to connect the applications, services, or processes on different devices for data exchange. They work with the IP addresses to ensure that the right application gets the data they requested. It is done via network port numbers. A network port number gets assigned to the IP address, which specifies the location of the application. Ports in networking are broadly divided into two categories: TCP and UDP Ports. These TCP and UDP ports are further divided into well-known ports, registered ports, and Dynamic or private ports. We shall learn about them in detail in further sections.

Get CompTIA Network+ Certified – Build a Strong Foundation in Networking!

Enroll Now and boost your career with globally recognized certification and job-ready skills!

Explore Program

Why are Network Ports called “Virtual Ports”?

• Network Ports are called “virtual” connection points because network ports do not physically exist as hardware. They are created as well as managed by the operating system. These “virtual ports” exist in software and work in the background.
• A virtual port allows a computer to handle multiple communication streams at once, when it usually has only one physical connection, via an Ethernet port or a Wi-Fi card.
• Each port is represented by a port number, for example, 80 for HTTP, and the operating system uses this number to direct incoming and outgoing network traffic to the correct application.

How Do Network Ports Work?

Network ports operate in combination with IP addresses to ensure accurate delivery of information over a network. An IP address and port number together function like a postal system, where the IP address is the location and the port number is the specific recipient (application). So, let us explore exactly how ports and IP addresses work together.

Let us look at the step-by-step working of IP addresses and ports to deliver your data.

Step 1: Finding the IP address

Every device connected to a network has a unique IP address. The IP address indicates the locality in which the device lies. For example, your router is connected to the network (let’s say your local ISP). The router will have an IP address that identifies it within the network. Your system will have a private IP address assigned by the router using DHCP. The data will first reach this IP address (the router device).

Step 2: MAC Address

Once the package has reached the locality, it needs to find the house. The house will be your computer device, and the package is the data. It could be a desktop, laptop, or printer. It finds that through the MAC address. Routers use MAC addresses to deliver the data to the right device within the local network.

Note: MAC addresses are only used within the local network and are not used once the data goes beyond the local network.

Step 3: Network Ports

Once the data has found the house, the package needs to go to the correct room. The room is an application or a service that can be found on your computer device (house). The data finds the application through the port numbers. Each application uses a network port number to interact with the network. The network port number tells the device which application or service should handle the data. For example,

• Port 80 is the port for a Web browser (HTTP)
• Port 443 is the port for Secure Web Browser (HTTPS)
• Port 25 is the port for the Email server (SMTP)

The operating system uses the port number to deliver the data to the proper application.

Let us suppose you open a browser and visit a website.

• Your computer uses a random high-numbered port (54832, for example) as the source port.
• It sends a request to the destination port 80 (HTTP) on the web server.
• The web server responds to your port 54832 with the website data.

What is the Importance of a Network Port?

The importance of ports in networking cannot be overstated, especially in enabling communication across services on the internet. It is crucial for achieving multitasking on a single device without interfering with the ongoing communication.

• The primary network port functionality is to properly direct the individual data packets to their intended application. This is a very important step after the IP address is found. The OS will locate the exact software and forward the data to it. This is how ports and IP addresses work together.
• Ports allow multiple services to run simultaneously on a single network device. For example, your computer can have a web browser, an email client, and an online game running simultaneously, all communicating through their port number in networking. This ability to multiplex various applications and services is an important characteristic for today’s multitasking operating systems.
• Every network connection involves a source port and a destination port. When your computer initiates a connection, it uses a dynamic port in networking, also known as an ephemeral port, which ranges from 49152 – 65535 as a source port. This sends data to a specific destination port on the server. The server then uses the source port to send data back, establishing robust network communication ports.
• Some common port numbers are accepted universally for particular services. For example, ports 80 and 443 are reserved ports for HTTP and HTTPS web traffic, respectively. This standardization is especially done for well-known ports (0-1023), which helps guarantee that different systems on the Internet can communicate reliably. Examples of well-known ports are Port 22 for SSH and Port 25 for SMTP.

Categorizing Port Numbers: Well-Known, Registered, and Dynamic

Port numbers in networking are numbers used to distinguish between different services or applications running on the same device. Some are assigned by the operating systems, and some are already registered. Therefore, port numbers can be categorized into three broad categories: Well-known ports, registered ports, and private ports. Let us look at each of them comprehensively.

Well-Known Ports (0-1023): The Standard Services

Well-known ports are reserved for the most common and fundamental network services. They are standardized by the Internet Assigned Numbers Authority (IANA) and are essential for core internet functions.

Some of the common, well-known ports are

• Ports 20 & 21: File Transfer Protocol (FTP) – It is used for transferring files between computers.
• Port 22: Secure Shell (SSH) – This port handles secure remote access to computers.
• Port 53: Domain Name System (DNS) – It is responsible for translating domain names into IP addresses.
• Port 80: Hypertext Transfer Protocol (HTTP) – This port is used for accessing websites.

Registered Ports (1024-49151): For Specific Applications

Registered ports are also registered with the IANA, but they are not as well-known as the above ports. These registered port numbers are used for specific applications or services. Developers use them for their custom applications to avoid conflicts with well-known services. They apply for these ports, and then IANA assigns them a port number after validation.

For example:

• Port 8080 is often used as an alternative HTTP port, especially for web proxies or development servers.
• Port 1433 is reserved for Microsoft SQL Server and is used for database communication.
• Port 3306 is reserved for MySQL.

Dynamic or Private Ports (49152-65535): Ephemeral and Temporary

When your computer connects to a website, it usually picks a random port from a range known as private or ephemeral ports. These aren’t listed with the IANA, and you typically won’t assign them manually. Instead, the operating system takes care of the dynamic port assigning, choosing one on the fly whenever a client, like your browser, needs to talk to a well-known or registered port. The moment the session ends, the ephemeral port is freed up and can be reused. Because they’re handed out as needed, people also call them dynamic ports in the world of networking.

Difference between TCP and UDP ports

Network port numbers can also be categorized into TCP and UDP ports. TCP is a secure connection established by confirming the identity of the destination IP before performing any data exchange. UDP is an unreliable and connectionless protocol that sends data without confirming the identity of the destination. TCP is a reliable connection as compared to UDP, which is an unreliable connection. We have compiled the difference between TCP and UDP in the table below.

Network Ports and Cybersecurity: Protecting Your Digital Gateways

Network ports play a crucial role in cybersecurity.

• In cybersecurity, firewalls and virtual ports protect users from unwanted network activity. Organizations have different levels of safety against attacks in cyberspace, and control port access by configuring firewalls to either block or allow traffic on certain ports. Protocols such as Network Address Translation (NAT) use network port numbers to identify and allow several internal devices to communicate through one public IP address. This makes NAT a key security feature, as it redirects incoming traffic to the correct internal device based on port mappings.
• Continuous monitoring of network communication ports can help detect unusual activity. Unexpected traffic or an unusual volume of traffic on active ports could signal an attempted breach or an ongoing attack. Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) use port information to identify malicious patterns.

Advance Your Career with IIT-Certified Cyber Security Training!

Enroll Now and become a certified cyber security professional with one of India’s premier institutes!

Explore Program

Conclusion

Throughout this article, you have learned that network ports, also known as virtual ports, are responsible for establishing communication between applications and services of two or more devices. Unlike physical ports like USB or Ethernet, they are not physically visible. We understood that each application and service has a unique port number assigned to it, through which they can communicate. Network ports are important for multitasking through a network and for security reasons. Network ports make connections in two ways: TCP and UDP. One requires a handshake to establish, whereas the other does not. As a student of cybersecurity and forensics, you must understand the various network ports and their importance in computer networks and connections.

To deepen your understanding, explore our Cybersecurity Course and prepare for interviews with this Cybersecurity Interview Questions Guide.

What are Ports in Networking? – FAQs