Paessler PRTG

PRTG port scanner for monitoring
the status of ports


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    Increase network security
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    Reliably check the status of ports
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    Quickly check for open ports and weak spots
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    Customize notifications and alerts








PRTG is a reliable port scanner that monitors data streams around the clock.


What is a port scanner?

A port scanner is a tool that checks the status of ports. It uses queries to determine whether a port is open, closed, or hidden.

  • Open port: The computer accepts the query, responds, and asks what to do next.
  • Closed port: The computer responds to the query and indicates that the port is in use and therefore unavailable.
  • Hidden port: The computer provides no response to the query. The port may be hidden, filtered, locked, or blocked.

Some port scanners also scan open ports for additional information (such as the operating system in use), but this is not their primary purpose.



What is a port?

Ports are part of a network address (IP address). They ensure connections and data packets are assigned correctly and allow for the processing of services on the Internet. This may involve the transfer of data, the retrieval of an email, or the sending or receiving of a web page. Ports use a transport protocol to transmit information. Each port is assigned a non-random number. These numbers range from 0 to 65535, with 1 to 1023 used for Internet protocols. 

What is a transport protocol?

A transport protocol – aka a “network protocol” – specifies how data is to be exchanged between the components in a network. In other words, it defines the way in which data is transmitted. The two most common protocols are the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP). PRTG can be used as a port scanner for both TCP and UDP.

Frequently used ports

Here are the most common ports and their uses:

  • Ports 20 and 21: Transfer of files
  • Port 25: Sending of emails
  • Port 53: Assignment of names to an IP address (DNS)
  • Port 80: Sending and receiving of web pages
  • Port 110: Retrieval of emails

For the IP port scanner in PRTG, it doesn't matter which ports you use. The software detects all of them, which is why you can use it for all the ports in your company.


Why do I need a port scanner?

A port scanner like PRTG promptly scans for open ports, allowing you to check and control the security of your entire network. Open ports are dangerous as they make your network (and thus your entire IT system) vulnerable to attacks. Examples of attacks via open ports include the smuggling in of Trojans or the extraction of important company information. With the port scanner function in PRTG, you’ll benefit from the following advantages:

  • Quick and reliable identification of weak spots
  • Simple verification of the functionality of ports
  • Constant updates thanks to precise monitoring with a customizable alert system

A sneak peek at port monitoring with PRTG



How does a port scanner work?

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Transfer of data to a host

Port scanners work in a variety of ways. The simplest (and most common) way involves the uninterrupted transfer of data to a specific host. The port scanner notifies the system as soon as a data packet reaches an open port. Data packet types can also vary: TCP, UPD, ICMP, FIN, and ACK are just a few examples.

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Vertical or horizontal scanning

Port scanners can scan both vertically and horizontally. With vertical scans, a single network address is scanned on multiple ports. Horizontal scans, on the other hand, test several network addresses on a specific port (e.g., port 80).


Your network monitoring at a glance

Set up PRTG in minutes and use it on almost any mobile device.


PRTG comes with all the features you need, plus more your IT infrastructure won't want to live without.



PRTG monitors these vendors and applications in one view!


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PRTG helps you quickly check open ports



The port scanner function of PRTG lets you quickly and reliably scan for open ports. PRTG also comes with customizable notifications that alert you to open ports in real time – and thereby allow you to take appropriate security measures. During your monitoring, you’ll want to keep a close eye on the following ports:

Router ports

Router ports

Server ports

Server ports


A failed switch port or server port can affect the entire network. It is therefore vital that you know the status of these ports at all times. PRTG provides for the precise monitoring and scanning of your ports, allowing you to keep a constant eye on your entire system. What’s more, by regularly scanning your router ports, you’ll be able to optimize the use of your network capacity. In particular, PRTG lets you promptly take action before this capacity reaches its limit.


Trusted by 500,000 users and recognized
by industry analysts as a leader

“Fantastic network and infrastructure monitoring solution that is easy to deploy and easier still to use. Simply the best available.”

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“Software is absolutely perfect, Support is superior. Meets all needs and requirements, this is a must have solution if you are needing any form of monitoring.”

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“The tool excels at its primary focus of being a unified infrastructure management and network monitoring service.”

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PRTG makes your job easier

Our monitoring software frees you to focus on other tasks by promptly notifying you of potential issues.


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Save effort

PRTG gives you one central monitoring tool for your servers and entire network. Enjoy a quick overview of your whole infrastructure via our dashboard and app.

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Save time

Getting started with PRTG is a breeze. Setting up or switching from another network monitoring tool is easy thanks to the auto-discovery and pre-configured device templates.

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Save money

80% of our customers report substantial cost savings with network monitoring. Your costs of licenses will likely pay for themselves within weeks.



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“The greatest advantage of PRTG? You get to rest easy.“

Steffen Ille, Bauhaus-University of Weimar, Germany


Create innovative solutions with Paessler’s partners

Partnering with innovative vendors, Paessler unleashes synergies to create
new and additional benefits for joined customers.


By integrating PRTG with Martello iQ, you can add a fast analytics layer to improve uptime, visualize your IT environment, and integrate all of your IT systems into a single pane of glass.

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Paessler and Plixer provide a complete solution adding flow and metadata analysis to a powerful network monitoring tool.

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Siemon and Paessler bring together intelligent building technology and advanced monitoring and make your vision of intelligent buildings and data centers become reality.

Read more


The advantages of using
PRTG as your port scanner tool

With PRTG, you get an all-in-one tool for all your IT monitoring and port scanning needs. You can do away with individual monitoring solutions and enjoy the convenience of a single, comprehensive tool. Among other things, PRTG comes with:


Alle Geräte

Monitoring for all devices


Network monitoring



Overview of open ports and security risks



Access to all the most common monitoring protocols


Solutions for small, medium, and large environments



Customizable thresholds and notifications



PRTG the multi-tool

PRTG: The multi-tool for sysadmins

Adapt PRTG individually and dynamically to your needs and rely on a strong API:

  • HTTP API: Access monitoring data and manipulate monitoring objects via HTTP requests
  • Custom sensors: Create your own PRTG sensors for customized monitoring
  • Custom notifications: Create your own notifications and send action triggers to external systems
  • REST Custom sensor: Monitor almost everything that provides data in XML or JSON format


Still not convinced?



More than 500,000 sysadmins love PRTG

Paessler PRTG is used by companies of all sizes. Sysadmins love PRTG because it makes their job a whole lot easier.

Still not convinced?


Monitor your entire IT infrastructure

Bandwidth, servers, virtual environments, websites, VoIP services – PRTG keeps an eye on your entire network.



Try Paessler PRTG for free

Everyone has different monitoring needs. That’s why we let you try PRTG for free. Start now with your trial.




Network Monitoring Software - Version (February 14th, 2024)


Download for Windows and cloud-based version PRTG Hosted Monitor available


English, German, Spanish, French, Portuguese, Dutch, Russian, Japanese, and Simplified Chinese


Up to 100 sensors for free (Price List)

Unified Monitoring

Network devices, bandwidth, servers, applications, virtual environments, remote systems, IoT, and more

Supported Vendors & Applications

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