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PRTG blocks port 80 although I'm using SSL on port 443. How to free port 80?



In PRTG Administration Tool, I've set PRTG to SSL. All connections to the PRTG web interface go through port 443. Still, PRTG does not allow another application to use port 80 (I get an error message in the other application).

How can I clear port 80?

port prtg redirect registry ssl web-interface

Created on Jun 8, 2010 9:06:15 AM by  Daniel Zobel [Product Manager]

Last change on Jun 29, 2022 11:54:42 AM by  Brandy Greger [Paessler Support]

9 Replies

Accepted Answer



This article applies as of PRTG 22

PRTG automatically determines which ports to use

You set the PRTG web server to use SSL on port 443. However, on startup, the PRTG web server checks if port 80 is used on the host computer. If it is not, PRTG sets a redirect for port 80: All web connections to this port are redirected to port 443.

This is to avoid that users see a Connection failed message in case they do not include https:// when calling the PRTG web interface. If you want to use port 80 for other web applications, there are two solutions:

Solution #1: Start other services earlier than PRTG

If you start a program or service that uses port 80 before PRTG, port 80 is already taken on PRTG startup and therefore not blocked.

This can be achieved, for example, by changing settings in the Windows services. For example, you can start the PRTG service dependent on an Apache service, so that the Apache web server starts first.

Solution #2: Registry hack

If solution #1 is not possible, you can add a registry entry that disables port 80 redirection for PRTG. Make sure to create a backup before you edit the registry.

In the registry editor, go to:

32-bit: HKLM\Software\Paessler\PRTG Network Monitor\Server\Webserver
64-bit: HKLM\Software\Wow6432Node\Paessler\PRTG Network Monitor\Server\Webserver

Note: For the deprecated PRTG versions 7 and 8, you might see the values in the additional subkey V7 or V8.

There, create a new DWORD value with the name:


Set this value to 1 to disable port 80 redirection. Set it to 0 to enable port 80 redirection again.


Created on Jun 8, 2010 9:07:52 AM by  Daniel Zobel [Product Manager]

Last change on Jun 1, 2022 1:35:10 PM by  Brandy Greger [Paessler Support]



Only for information: On 64 bit the reg path is

HKLM\SOFTWARE\Wow6432Node\Paessler\PRTG Network Monitor\Server\Webserver

Created on Jan 16, 2012 3:35:48 PM

Last change on Jan 16, 2012 4:13:00 PM by  Daniel Zobel [Product Manager]



Hello, this solution doesn't work when you use an other port for HTTP. We do not you SSL for PRTG. We have change the HTTP Port from 80 to 83 with the registry hack but with no luck.

Created on Feb 2, 2012 8:29:31 AM



This hack does not change the HTTP Port, this only disables the redirect from port 80. So the only values which are accepted for 'NoSSLRedirect' are 1 and 0.

Created on Feb 2, 2012 3:39:20 PM by  Torsten Lindner [Paessler Support]



I know. The value "NoSSLRedirect" is set to 1. I have set the HTTP Port in the administration to 83 but PTRG use also port 80.

Created on Feb 3, 2012 12:07:38 PM



Sorry, I made a mistake there, of course the registry hack only works when the PRTG Webserver is set to serve HTTPS on port 443. But if you set the Webserver to serve normal HTTP on another port than 80, port 80 will be free and not used by the "PRTG Server.exe".

Created on Feb 3, 2012 4:21:54 PM by  Torsten Lindner [Paessler Support]




Before to install the product, I'd like to know if it's possible to set another ports thand 80 and 443 because they're already in use on my server.



Created on May 30, 2018 1:24:10 PM



Hi there,

You can choose any other port that is free on the server. There are no fixed ports. You can change them in the "PRTG Administration Tool" under the "Web Server"-Tab:

Created on May 30, 2018 1:29:10 PM by  Dariusz Gorka [Paessler Support]

Last change on May 30, 2018 1:29:19 PM by  Dariusz Gorka [Paessler Support]




Thanks, I could install it with the port 8080.


Created on May 31, 2018 7:53:29 AM

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.