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I cannot login to PRTG for Android on Android N. What can I do?

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The login with the PRTG mobile app on Android N does not work. When I try to connect to my PRTG server with PRTG for Android, I get an error because of a wrong password and the app shows the message that it “could not retrieve passhash”. I did not change my password.

This happens only on Android N. Connecting to the PRTG server via a web browser with the same credentials works. How can I login with PRTG for Android on my Android N device when it complains about the credentials?

android android-n diffie-hellman mobile-app passhash prtg prtg-for-android ssl

Created on Jun 28, 2016 5:16:27 PM by  Gerald Schoch [Paessler Support]



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This article applies to PRTG Network Monitor 16 or later and PRTG for Android 16 or later

Failed Logins to PRTG for Android on Android N

Android N includes several changes to its SSL library compared to previous Android versions. These changes also affect the secure connections between PRTG for Android and your PRTG server and may result in unsuccessful login attempts on Android N devices. The error message of PRTG for Android which may reflect this issue is “could not retrieve passhash”.

We have already released a PRTG update with version 16.2.23.3269/3270 that makes it possible to login with PRTG for Android on Android N. Please update PRTG to this version or higher. If you still cannot connect and see the passhash error message, the reason may be missing keys for the Diffie–Hellman key exchange (D–H). The required keys for establishing secure connections are not available by default sometimes, especially on older systems.

Connecting to PRTG from Android N

PRTG uses an elliptic curve for secure connections that Android N does not support. Because of this, Android N tries to use the Diffie-Hellman method as fallback. This will fail if D–H parameters are not available which results in the error message about an incorrect password.

If you run PRTG core server version 16.2.23.3269/3270 or later but you still cannot connect with PRTG for Android on Android N, please follow the steps below.

  1. On your PRTG core server system, navigate to the \cert subfolder of your PRTG program directory.
  2. Check if the file dh.pem is in this folder.
  3. If you cannot find dh.pem, execute the script generatedh.bat in the same folder to generate dh.pem.
  4. Restart the PRTG core server.

Try to login with PRTG for Android again. If the connection still does not work, please double-check the credentials you provide in the mobile app.

Created on Jun 28, 2016 5:20:12 PM by  Gerald Schoch [Paessler Support]

Last change on Jul 1, 2016 1:01:13 PM by  David Fabian [Paessler Support] (49) 3 1



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This does not fix the issue.

I have a later version of PRTG for Android, as this Article is from June. I'm running version 16.3.2

I have deleted the app and removed it.

I ran the batch file which created the dh.pem file. I then stopped the core servers and rebooted the OS. Once the OS booted back up and the core servers started. I tried again and I continue to get the same error “could not retrieve passhash”.

This is really getting frustrating. I understood during the beta preview of Android N that there would be issues. But this is the full released version of Android 7.0.

Created on Aug 29, 2016 5:56:47 AM by  Ryan Lestage (0)



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Hello,

Which exact PRTG Core Server version are you using?

Created on Aug 29, 2016 12:32:31 PM by  Jochen Greger [Paessler Support]



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Are you referring to the version Installed on the computer/web?

That would be 16.3.25.5767 Latest Android version is 16.3.2

Created on Aug 30, 2016 9:07:08 PM by  Ryan Lestage (0)



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This doesn't work because your OpenSSL implementation is broken (Maybe path missing somewhere?).

When I try to create the PEM using the batch file, the following is written to the log file;

5768:error:02001015:system library:fopen:Is a directory:.\crypto\bio\bss_file.c:175:fopen('D:\Projects\libraries\openssl\openssl-1.0.1t\00_openssl_binaries_32/ssl/openssl.cnf','rb') 5768:error:2006D002:BIO routines:BIO_new_file:system lib:.\crypto\bio\bss_file.c:180: 5768:error:0E078002:configuration file routines:DEF_LOAD:system lib:.\crypto\conf\conf_def.c:197:

Created on Sep 22, 2016 4:16:40 AM by  Rod Bacon (0)

Last change on Sep 23, 2016 11:12:34 AM by  Erhard Mikulik [Paessler Support]



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Hi Rod,

Which version of PRTG are you running? Also how does the generatedh.bat look like? It should contain something like this:

set OPENSSL_CONF=.\openssl.cnf ..\openssl.exe dhparam -out dh.pem -2 1024 2> dh.log

Kind regards,

Erhard

Created on Sep 23, 2016 11:19:13 AM by  Erhard Mikulik [Paessler Support]



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Hi, I'm having the same issue whit the PRTG android app sine upgrading to Android 7. Getting a "handshake" error on existing account. if I remove account on app and try to add a new one it show "error with SSL".

PRTG Server is fine and app works on other devices (IOS and Android) without issue. It's only since upgrading to Android 7 Nougat on Samsung S6 that the issue occurs. I tried the DH option in previous posts, restarted PRTG core and no difference. Running latest version of PRTG 17.2.30.1825

Created on May 30, 2017 12:19:01 PM by  smarthotspots (0)



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Hi there,

Make sure that you start the BATCH file as an administrator. If done, leave the command window opened till it finishes. Should an error occur, forward us a screenshot and the created log within the directory. Please also make sure that the PRTG Core Server is restarted once afterwards.

Best regards.

Created on May 31, 2017 8:35:34 AM by  Dariusz Gorka [Paessler Support]



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I'm having exactly the same issue.

Server is running 17.2.30.1825

The app was running fine until I received an update to android n (galaxy tab s2), then the app would not connect. My phone running android m connects fine.

I have regenerated the dh file as above (there was already a dh file) as administrator and rebooted the server, but no joy.

I just get "An SSL error has occurred" when I re-create the account.

Created on Jun 1, 2017 12:06:33 PM by  Al Slater (0)



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Hi there,

I am afraid that this topic is not the best for the Knowledgebase. Please open a new support ticket by submitting a support bundle to us. This can be done via the "Contact Support" ribbon in the lower right corner of the web interface. If the server has no internet connection you can mail us via support@paessler.com.

Best regards.

Created on Jun 1, 2017 8:13:13 PM by  Dariusz Gorka [Paessler Support]



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I am having the same problem. The error message points to this knowledgebase article. If there is another knowledgebase article for this problem could we get a link to it?

Created on Jun 21, 2017 7:39:43 AM by  Jarrad Thomas (0) 1



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Hi there,

Make sure that you start the BATCH file (to generate the dh.pem) as an administrator. If done, leave the command window opened till it finishes. Should an error occur, post the content the created log within the directory. Please also make sure that the PRTG Core Server is restarted once afterwards.


Best regards.

Created on Jun 21, 2017 7:49:08 AM by  Dariusz Gorka [Paessler Support]



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I have started the batch file and it is still running, but as with some of the other posts above I don't think it will fix the problem. I am running server version 17.1.28.1032+ and the error started with the latest Android update on my Galaxy S6. I know this is probably a different problem and should be separated from this knowledge base article, but the error message gives a link to this page. If there is somewhere else for this information could we get a link to it?

Created on Jun 21, 2017 7:57:38 AM by  Jarrad Thomas (0) 1



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Hi there,

The issue is, that Android 7 has some improved security features which require ECC (Elliptic curve cryptography) on the webserver of PRTG. To use this, you have to generate the DH.pem. The generation will need some time, depending on the hardware and current load. After you have successfully generated the DH.pem, you have to restart the PRTG Core Server Service.


Best regards.

Created on Jun 21, 2017 8:37:10 AM by  Dariusz Gorka [Paessler Support]



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Hi,

I'm having the exact same problem.

I'm unable to create account with my Huawei (android 7.0) while colleagues with other versions or iPhone have no problem.

I tried the above twice (generated dh.pem, with 1024 or 2048 bits key and restart PRTG core, with no effect).

No error in ph.log neither ....

Created on Nov 29, 2017 3:42:45 PM by  Dsquare (0)



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Hi there,

What exact errors do your colleagues exactly get on the Huawei? Is it "An SSL Error occured.." errors that is displayed on login?

Best regards.

Created on Nov 30, 2017 7:49:12 AM by  Dariusz Gorka [Paessler Support]



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Is there any update/fix for this issue? I am running Android 7.0 and I too all of a sudden was not able to access my PRTG installation from my app. I uninstalled and reinstalled the app and now I cannot log in from the app at all. I keep getting the error message "I could not retrieve the passhash. Perhaps your password is wrong?" (my password is definitely correct as I can log in from a browser). My PRTG core server has the dh.pem file with a modified date of 3/31/2016, so it has been there for awhile. I'm running version 17.3.32.2478. It sounds like there may be other issues preventing login from Android 7.0, please help.

Created on Jan 11, 2018 3:55:13 PM by  craigcs (0)



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Hi craig,

Please open a browser on the phone and try to connect to the webinterface of PRTG, does that work?

Best regards.

Created on Jan 12, 2018 8:24:11 AM by  Dariusz Gorka [Paessler Support]



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Same problem, get an SSL error but can login via a web app on the phone

Created on Mar 7, 2018 3:57:40 PM by  Kobit (0) 1



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Hi there,

Have you tried the steps in the mentioned KB-Article? Even if the first look indicates that the KB-Article is unrelated to the problem, it is actually the solution. In newer PRTG versions we implemented ECC (Elliptic curve cryptography) which creates issues on Android 7 devices. Therefore you have to generate the DH.pem as described in the article. Pleas make sure that you start the BATCH file as an administrator. If done, leave the command window opened till it finishes. Should an error occur, forward us a screenshot and the created log within the directory. Please also make sure that the PRTG Core Server is restarted once afterwards.

Should this not work, try the following commands:

  • open a command line (cmd.exe) as an administrator
  • issue the following commands:
    cd "C:\Program Files (x86)\PRTG Network Monitor\cert\"
    generatedh.bat

    Best regards.

Created on Mar 7, 2018 8:26:38 PM by  Dariusz Gorka [Paessler Support]

Last change on Mar 7, 2018 8:26:47 PM by  Dariusz Gorka [Paessler Support]



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I was just struggling with this and I did run the bat file to generate the new dh.pem file. I was waiting for aa few hours until we could restart the server.

However, a colleague showed me the option to use the QR barcode from the web interface to set up an account in the Android app. I used that within the Android app and for some reason my password was accepted this time without the complaint about a "passhash" issue. I can't say why it worked but try it if you are struggling.

My phone is Android Nougat ( N or 7.x ) and we are on 17.x version of PRTG.

Created on Apr 30, 2018 3:33:05 PM by  GwigstaNummerEin (0) 1

Last change on May 1, 2018 6:04:02 AM by  Dariusz Gorka [Paessler Support]



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A few days ago stopped with this error on my Samsung S8+ 8.0. S9+ without any problems. I've tried today upgrade to latest version, no difference. I've been tried generatedh.bat with restart, no change. I've tried move to builtin certificate from Paessler and generatedh.bat and restart, still no success. S9+ works in all cases. I think that a few days ago was Android application upgrade, so I think there is an error in it.

Created on May 18, 2018 12:57:09 PM by  Vaclav Panenka (0) 1



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Hello Vaclav,

I've just tested on my end with the current PRTG app version, last updated on May, 4th according to Google Play store and it worked without issues (Huawei P9, Android 7.0). I'll talk to the dev, he should be able to provide a debug version to analyze this further.

Kind regards,

Erhard

Created on May 18, 2018 1:21:12 PM by  Erhard Mikulik [Paessler Support]



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Hello Vaclav,

We need a few more details to analyze this, I'll send you an email about it.

Kind regards,

Erhard

Created on May 22, 2018 8:23:50 AM by  Erhard Mikulik [Paessler Support]



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Registered to say that this solution worked quickly and perfectly! Thanks support and devs :)

  1. On your PRTG core server system, navigate to the \cert subfolder of your PRTG program directory.
  2. Check if the file dh.pem is in this folder.
  3. If you cannot find dh.pem, execute the script generatedh.bat in the same folder to generate dh.pem.
  4. Restart the PRTG core server.

Created on Jun 17, 2018 11:24:15 PM by  darxtorm (20)

Last change on Jun 18, 2018 6:15:59 AM by  Erhard Mikulik [Paessler Support]



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same problem here, but solved with earlier mentioned solution:

... the option to use the QR barcode from the web interface to set up an account in the Android app. I used that within the Android app and for some reason my password was accepted this time without the complaint about a "passhash" issue. I can't say why it worked but try it if you are struggling.

Created on Aug 11, 2018 10:34:46 PM by  bartplessers (10)



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Strange but true, QR barcode from My Account page help to avoid this problem for me.

Created on Nov 8, 2018 10:47:17 AM by  Vasiliy (0) 1



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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.