The vCenter Server must set the distributed port group Promiscuous Mode policy to "Reject".

When promiscuous mode is enabled for a virtual switch, all virtual machines connected to the port group have the potential of reading all packets across that network, meaning only the virtual machines connected to that port group.

Promiscuous mode is disabled by default on the ESXi Server, and this is the recommended setting.

If distributed switches are not used, this is not applicable.

From the vSphere Client, go to "Networking".

Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies.

Verify "Promiscuous Mode" is set to "Reject".

or

From a PowerCLI command prompt while connected to the vCenter server, run the following commands:

Get-VDSwitch | Get-VDSecurityPolicy Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy

If the "Promiscuous Mode" policy is set to accept, this is a finding.

From the vSphere Client, go to "Networking".

Select a distributed switch >> Select a port group >> Configure >> Settings >> Policies.

Click "Edit".

Click the "Security" tab.

Set "Promiscuous Mode" to "Reject".

Click "OK".

or

From a PowerCLI command prompt while connected to the vCenter server, run the following commands:

Get-VDSwitch | Get-VDSecurityPolicy | Set-VDSecurityPolicy -AllowPromiscuous $false Get-VDPortgroup | ?{$_.IsUplink -eq $false} | Get-VDSecurityPolicy | Set-VDSecurityPolicy -AllowPromiscuous $false