SSH algorithm support

In versions 2020.3.13.0 and later of Remote Desktop Manager, an error message can appear when opening a Secure Shell (SSH) connection: "An unexpected error has occurred: Error code SSH_FAIL_NO_MATCH (-3006) Unable to find a matching algorithm with the SSH server".

Local Solution for one entry

Remote Desktop Manager now has a selection of algorithms for the SSH session type. Please note that the unsecured ones are not enabled by default. We therefore recommend that you check the algorithms directly on your server for security purposes. Otherwise, you can follow the steps below to resolve this issue.

  1. Right-click on your entry and select Properties. Make sure you are in CommonGeneral in the left menu.

  2. In the Advanced tab, set the Algorithm support option to Custom.

    Custom Algorithm support
    Custom Algorithm support

  3. Click on the button that appeared to the right of the Algorithm support setting.

  4. In the new SSH window, select the missing algorithms from the list.

    Make sure to go through the algorithms in all tabs before proceeding.

    Missing Algorithms Selection
    Missing Algorithms Selection

  5. Click OK in the SSH window, then OK again in the window of the entry properties.

    You may have to restart Remote Desktop Manager for the solution to take effect.

  6. Test your connection. If you are still unable to connect after enabling the algorithms, return to the Advanced tab in your entry properties and check the Skip environment variable setup box and click OK.

    Skip environment variable setup
    Skip environment variable setup

Global Solution for all entries

It is also possible to globally reactivate all the algorithms in Remote Desktop Manager via the FileOptionsTypesTerminalAlgorithm Support menu. Just select the missing algorithms, then click OK.

Make sure to go through the algorithms in all tabs.

You may have to restart Remote Desktop Manager for the solution to take effect.

File – Options – Types – Terminal – Algorithm Support
File – Options – Types – Terminal – Algorithm Support

Custom Powershell command script

If you still encounter issues on a specific entry, you can run the following PowerShell script in Remote Desktop Manager.

  1. Right-click on the problematic entry, then select Edit – Edit (Special Actions).
  2. In the Edit – Special Action Selection window, select the Custom PowerShell Command general special action and click OK.
    Edit – Special Action Selection
    Edit – Special Action Selection
  3. Paste the following script in the Command field:
    $Connection.Terminal.AlgorithmSupportMode = "Custom"
    $Connection.Terminal.SshAlgorithmCipherList = "aes256-gcm@openssh.com=True;aes128-gcm@openssh.com=True;aes128-cbc=True;aes192-cbc=True;aes256-cbc=True;rijndael-cbc@lysator.liu.se=True;3des-cbc=True"
    $Connection.Terminal.SshAlgorithmHostKeyList = "ssh-dss=True"
    $Connection.Terminal.SshAlgorithmKexList = "diffie-hellman-group14-sha1=True;diffie-hellman-group-exchange-sha1=True;diffie-hellman-group1-sha1=True"
    $Connection.Terminal.SshAlgorithmMaclist = "hmac-sha1-96=True;hmac-sha1=True;hmac-md5-96=True;hmac-md5=True"
    $RDM.Save();
    
  4. Click OK.
    Custom PowerShell Command
    Custom PowerShell Command
  5. A notification should confirm the success of the script. Click OK and retest your session.