7.2.1 Ensure that port groups are not configured to the value of the native VLAN

Information

Do not use Native VLAN ID 1.

*Rationale*

ESXi does not use the concept of native VLAN. Frames with VLAN specified in the port
group will have a tag, but frames with VLAN not specified in the port group are not tagged
and therefore will end up as belonging to native VLAN of the physical switch. For example,
frames on VLAN 1 from a Cisco physical switch will be untagged, because this is considered
as the native VLAN. However, frames from ESXi specified as VLAN 1 will be tagged with a 1;
therefore, traffic from ESXi that is destined for the native VLAN will not be correctly routed
(because it is tagged with a 1 instead of being untagged), and traffic from the physical
switch coming from the native VLAN will not be visible (because it is not tagged). If the
ESXi virtual switch port group uses the native VLAN ID, traffic from those VMs will not be
visible to the native VLAN on the switch, because the switch is expecting untagged traffic.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

If the default value of 1 for the native VLAN is being used, the ESXi Server virtual switch
port groups should be configured with any value between 2 and 4094. Otherwise, ensure
that the port group is not configured to use whatever value is set for the native VLAN.

See Also

https://workbench.cisecurity.org/files/902

Item Details

Category: SYSTEM AND INFORMATION INTEGRITY

References: 800-53|SI-4

Plugin: VMware

Control ID: 75ebe713ae301ea075ab7c5ad9870d91ae4b8b9fdde95960bf31e80d165b7b73