Information
By default, remote console sessions can be connected to by more than one user at a time. Permit only one remote console connection to a VM at a time. Other attempts will be rejected until the first connection disconnects.
Rationale:
When multiple sessions are activated, each terminal window gets a notification about the new session. If an administrator in the VM logs in using a VMware remote console during their session, a non-administrator in the VM can connect to the console and observe the administrator's actions. Also, this could result in an administrator losing console access to a VM. For example, if a jump box is being used for an open console session, and the admin loses a connection to that box, the console session remains open. Allowing two console sessions permits debugging via a shared session. For highest security, only one remote console session at a time should be allowed.
Solution
To set this configuration utilize the vSphere interface as follows:
Select the VM then select Actions followed by Edit Settings.
Click on the VM Options tab then expand Advanced.
Click on EDIT CONFIGURATION.
Click on ADD CONFIGURATION PARAMS then input RemoteDisplay.maxConnections with a value of 1.
Click OK, then OK again.
Alternatively, run the following PowerCLI command for VMs that do not specify the setting:
# Add the setting to all VMs
Get-VM | New-AdvancedSetting -Name 'RemoteDisplay.maxConnections' -value 1
Run the following PowerCLI command for VMs that specify the setting but have the wrong value for it:
# Add the setting to all VMs
Get-VM | New-AdvancedSetting -Name 'RemoteDisplay.maxConnections' -value 1 -Force