VMware Workstation – Unable to connect to the MKS: Login incorrect

Today i ran into the problem that i wasn’t able to connect to my vCenter via VMware Workstation. If you’re working in your homelab it’s probably helpful sometimes to have access to a VM console without to connect to an ESXi host, a vCenter Web Client or even via RDP to some management client. You can easily connect to your vCenter with VMware Workstation. I wrote a short article about how to save the login credentials in VMware Workstation.

The error message i’ve had was:

Unable to connect to the MKS: Login (username / password) incorrect


I’m pretty sure that this wasn’t the case. I’ve tried it with the @vsphere.local admin and also with my domain administrator. But no success.

When i searched for a solution i’ve found many hints and tips. Let me show you what i’ve found and what was my solution at the end.

Check the ESXi firewall

Next step is to make sure that the ESXi firewall isn’t blocking communication. Make sure the following incoming ports are open: 443, 902, 903

I checked that, all ok. But i still got this error message. The only port i didn’t see on the firewall port list was 903. And i wasn’t able to open this port. But i knew that this wasn’t the issue when i connected my vCenter to my VMware Workstation the last time.

Edit a config file on your ESXi host

Well, i’m not sure if that’s the way to go. Thinking about possible updates etc. some configuration files might get overwritten. But i checked it anyway. It’s in my lab and when something goes wrong or does not work, i can fix it and learn something.

You can use Putty / SSH and vi to edit this file, or go comfortable with WinSCP. Connect to your ESXi host and locate the config file at /etc/vmware/config.

Add the line vmauthd.server.alwaysProxy = „TRUE“

I’m also not sure if a restart is necessary, i did a restart, but it didn’t work either.

Use another port for authentication

You can try to edit the config.ini file in VMware Workstation, located at „C:\ProgramData\VMware\VMware Workstation\config.ini„.

Change the line authd.client.port = „903“ to authd.client.port = „902“. After that restart the „VMware Authorization Service“ and you should be fine.

That did the trick on my system, i was able to connect to my VMs through VMware Workstation.

Hint: if you’re working with Notepad++ (highly recommended!) then you’re able to save the file after granting administrative access (you see what i mean when you try to save the file). If you’re working with another text editor, you should start this text editor as administrator (just right click => run as administrator). Otherwise you probably won’t be able to save the changes.

VMware Workstation – Save login information for remote host

This post is gona be a short one. It was once again a problem for which I needed a solution. Today i was working in my vSphere homelab. I’ve set up some more virtual machines, installed my availability software of choice and did some reading. If you are a VMware Workstation user, then you probably know the feature to connect to a remote server, like, for example a vCenter Server. That’s a pretty handy feature which i really like. You can connect to your lab environment and you can access all your VMs directly and easy, without any remote desktop and stuff.

One thing about this feature was quite annoying for me. Everytime when i connected to my lab environment i had to enter my credentials. It didn’t bother me very much, it was just annoying. So i searched for more information but there wasn’t much. Then I found a VMware communities post which asked how to clear these credentials. I did some reverse thinking and found the options in the settings of VMware Workstation.

How to save login information

If you now would like to know how you can save your credentials, then just follow this quick steps:

  1. Click on „Edit“ => „Preferences…“.

  2. On „Workspace“ look for „Privacy“ and click the checkbox „Offer to save login information for remote hosts“.

    VMware Workstation Preferences - Workspace

  3. Aaaand you’re done.

The next time you click on your lab environment (or any other remote host) then there is a pop up which asks you if you want to save the login or not.