Details
Set the vSwitch Forged Transmits policy to reject for each vSwitch. Reject Forged Transmit
can be set at the vSwitch and/or the Portgroup level. You can override switch-level settings
at the Portgroup level.
*Rationale*
If the virtual machine operating system changes the MAC address, the operating system can
send frames with an impersonated source MAC address at any time. This allows an
operating system to stage malicious attacks on the devices in a network by impersonating a
network adaptor authorized by the receiving network. Setting forged transmissions to
accept means the virtual switch does not compare the source and effective MAC addresses.
To protect against MAC address impersonation, all virtual switches should have
forged transmissions set to reject.
Solution
1. In the vSphere Web Client, navigate to the host.
2. ‘Hosts and Clusters’ -> ‘vCenter’ -> host.
3. On the Manage tab, click Networking, and select Virtual switches.
4. Select a standard switch from the list and click the pencil icon to edit settings.
5. Select Security.
6. Set Forged transmits to ‘Reject’.
7. Click ‘OK’.
Additionally, the following ESXi shell command may be used-
# esxcli network vswitch standard policy security set -v vSwitch2 -f false
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: System and Communications Protection.This control applies to the following type of system VMware.