Find a port number for programs and processes [Guide]

Programs, apps, and procedures rely on a unique port number for a smooth-running data flow. A simple explanation would be to depict the relation between these endpoints and IP addresses. In this case, an IP address indicates a device set to receive information online. The port number goes further, instructing how and where a device needs to process it. Each internet-connected device innately knows all standardized ports with assigned numbers. However, there are cases when you might need to tweak ports for easier access or performance.

What is a port number? 

A port number is a standard number representing different requests, programs, and processes. In network communications, they help servers and computers identify the incoming and outgoing connections. 

So, ports enable devices to differentiate between types of traffic. All well-known procedures like browsing, emails, torrenting, or streaming have individually assigned port numbers. 

So how do devices and servers understand each other and can identify specific ports? Well, all of them can recognize these standardized port numbers automatically. 

You can see port numbers as extensions of IP addresses. The latter pinpoint particular devices, while port numbers represent services and applications within them. Essentially, these numbers are instructions for how a device needs to handle incoming or outgoing traffic. 

Port numbers are 16-bit unsigned integers and can be anything between 0 to 65535. Of course, some of them are more well-known than others. For instance, HTTP traffic runs through the 80 port, while FTP travels via port 20. 

Some common port numbers and port types

There are three types of port numbers. Let’s examine each category and illustrate it with a brief port number list. 

System ports

Such port numbers range from 0 to 1023 and are well-known ports. Essentially, they represent the most common processes in networking. 

• File Transfer Protocol (FTP) - 20, 21. 
• Secure Shell (SSH) - 22.
• Telnet - 23. 
• Simple Mail Transfer Protocol (SMTP) - 25. 
• IPSec - 50, 51.
• Domain Name System (DNS) - 53. 
• Dynamic Host Configuration Protocol (DHCP) - 67,68. 
• Trivial File Transfer Protocol (TFTP) - 69.
• Hypertext Transfer Protocol (HTTP) - 80. 
• Simple File Transfer Protocol (SFTP) - 115. 
• Hypertext Transfer Protocol Secure (HTTPS) - 443. 

Registered ports 

These port numbers range from 1024 to 49151. IANA assigns them for particular services, like companies using them for their server applications. Registered port numbers are not universal, and they do not warrant the need for a well-known port. 

• SOCKS proxy - 1080. 
• OpenVPN - 1194.
• Point-to-Point Tunneling Protocol (PPTP) - 1723.
• Diablo II game - 4000.
• League of Legends - 5000-5500. 
• Steam game client traffic - 27000–27015.

Dynamic ports 

These port numbers, also known as private, get assigned to a process or program at a time of need. They range from 49152 to 65535. Users or companies can use them for their internal procedures. 

• Certificate Management over CMS - 49152–65535.
• Mumble - 64738.

How do ports work? 

Most application data transfers online use either TCP or UDP. Such traffic also relies on port numbers linked to one or both of these protocols. For instance, DHCP uses UDP ports 67 and 68. However, HTTP strictly uses TCP port 80. So, ports can communicate differently, depending on the purpose and protocols. 

For instance, the TCP protocol is more reliable, and it prioritizes data integrity and security, meaning it operates slower. Thus, it is the choice for email services and web pages. However, some data exchanges can greatly benefit from UDP, which splendidly works in speed-sensitive situations. 

Usually, port numbers work seamlessly, and users won’t need to tweak or fix anything. However, their operation can hinder certain goals, like a firewall preventing specific port numbers from passing. Common fixes include port forwarding, which enables devices outside your home network to connect to your device. 

What is my port number on Windows and macOS? 

If you need to configure your firewall or grant access to certain programs, you will need to know your port number. The process differs depending on the operating system you have. 

On Windows: 

1. First, you need to have admin rights on your Windows device. 
2. Open the Start menu and type cmd. 

3. In the Command Prompt window, write netstat -a and hit enter. 

On macOS: 

1. Open Spotlight Search by hitting Command+Spacebar and entering the word terminal. 

2. Type netstat -an and press enter. 

3. You should see all ports and numbers.