7.2 Ensure the vSwitch MAC Address Change policy is set to reject


Ensure the MAC Address Change policy within the vSwitch is set to reject. Reject MAC Changes can be set at the vSwitch and/or the Portgroup level. You can override switch-level settings at the Portgroup level.


If the virtual machine operating system changes the MAC address, it can send frames with an impersonated source MAC address at any time. This allows it to stage malicious attacks on the devices in a network by impersonating a network adaptor authorized by the receiving network.


This will prevent VMs from changing their effective MAC address. It will affect applications that require this functionality, such as Microsoft Clustering, which requires systems to effectively share a MAC address. This will affect how a layer 2 bridge will operate. This will also affect applications that require a specific MAC address for licensing. An exception should be made for the port groups that these applications are connected to.


To set the policy to reject, perform the following:

From the vSphere Web Client, select the host.

Click Configure then expand Networking.

Select Virtual switches then click Edit.

Click on Security.

Set MAC address changes to Reject in the dropdown.

Click on OK.

Alternately, perform the following using the ESXi shell:

# esxcli network vswitch standard policy security set -v vSwitch2 -m false

See Also