What is an open port and how to secure them

I have open ports. What now?

Learn what an open port is,

Why open ports could be a security risk, and

How System Mechanic’s Network Scanner can help you identify and manage them

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What are open ports?

The term port refers to a conduit or communication endpoint used to connect to another device over a network. An open port identifies a specific application or service, assigns a numerical value to it, and then transmits the data from one side to the other.

An example of this would be using your home computer to visit a web page. Your device uses a dedicated port number (443) on servers specifically assigned to Hypertext Transfer Protocol (HTTPS) to connect you to the Internet.

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What are the two types of open ports?

All devices connected to the internet primarily use two Transport Layer Network Protocols, Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) by opening a port from one device to another to communicate and send data. Both send information via packets, or units of data grouped together. Computers using TCP establish a reliable connection directly with the computer they are sending data to, which guarantees that packets are received.

Devices using UDP also connect directly to one or more devices they are sending data to, but their data is streamed without any acknowledgement that the packets are received by the other device.

Note that a closed port rejects or ignores packets either because it is unreachable or there’s no application able to receive the incoming information.

What are some of the top ports likely to be in use on my network?

There are 65,535 available ports that your router and network devices can use to establish network and internet connections. The most common and well-known are below port 1000, for example

FTP 21
POP3 110
POP3 SSL 995
IMAP 143
SMTP 25 (Alternate: 26)
MySQL 3306
cPanel 2082
CPanel SSL 2083

Are all open ports bad?

TLDR; no. And to help illustrate this point, we’ll share this analogy with you:

“That’s like asking if an unlocked door on your house is bad. It depends on why it’s unlocked and if you know or not. If you unlocked it, because you’re expecting a friend to enter, then it’s good.If it’s unlocked in the middle of the night, and you didn’t know, it’s potentially bad.

If you have a port open for a good reason, then it might be ok but still presents some risk. Ideally, you’d have a way to validate who is accessing the service at each port. This is what firewall rules do.”

Ports are essential and allow us to communicate over a network. And while open ports are not inherently dangerous, a misconfigured server or router with shoddy security rules, or vulnerable software can be dangerous.

Scan for open ports with System Mechanic

How can I monitor and secure open ports?

If you have a PC or Windows device, you can install PC privacy and performance software like iolo’s System Mechanic which has a built-in Network Scanner utility that searches for open ports.


Scanning for open ports using System Mechanic

  1. From the performance dashboard, click on the dropdown and select “Toolbox” from the list.
  2. Next, click on “Network Scanner”.
  3. Click on “Open Ports” and then the red “Scan Now” button.
  4. If discovered, “Suspicious Open Ports” will display a list of questionable ports by IP address
    1. Note: All links provided are completely safe to click on
  5. Research port numbers using a search engine like Google
  6. To block an open port, from the Windows task manager type in “Firewall & network protection”
  7. Next, click on “Advanced settings”
  8. In the left menu click on “Inbound Rules” and then “New Rule”
  9. Select the “Port” radio button and then click “Next”
  10. Enter the specific port number in the field and then click “Next”
  11. Finally, select “Block the connection”

It’s a good idea to scan your PC for open ports regularly to help identify possible security vulnerabilities or open pathways that could be potentially exploited by hackers.

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What is iolo's Whole Home License?

The Whole Home License® is iolo’s licensing policy that allows you to install and keep your software running on all of your compatible devices within the same home. Previously, users were allowed to install and license their iolo software simultaneously on a maximum of three PCs. Under the Whole Home License, a single activation key allows you to use your iolo software on all of your PCs, other than any PCs you use for business purposes. What you need to know about Whole Home Licensing

  • You, your spouse, and your relatives living within the same household may use the same license on any number of PCs that you own which are not used for business.
  • For full legal terms and conditions, see https://www.iolo.com/company/legal/eula/

To install your iolo product on additional PCs:

  1. On the additional computer, download the latest version of your iolo product. Choose from the list of downloads offered here.
  2. Follow the steps in the installation wizard, and enter the same Activation Key that you used to install on your original computer.

You can view the Activation Key on the original computer from within System Mechanic > red menu bar > key icon > Activation Key.