Details
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
From the vSphere Web Client go to Networking >> Select a distributed port group >> Manage >> Settings >> Policies. Click Edit and under the VLAN section change the VLAN ID to a non-native VLAN and click OK.
or
From a PowerCLI command prompt while connected to the vCenter server run the following command:
Get-VDPortgroup ‘portgroup name’ | Set-VDVlanConfiguration -VlanId ‘New VLAN#’
Supportive Information
The following resource is also helpful.
This security hardening control applies to the following category of controls within NIST 800-53: Configuration Management.This control applies to the following type of system VMware.
References
- 800-53|CM-6b.
- CAT|II
- CCI|CCI-000366
- Group-ID|V-63973
- Rule-ID|SV-78463r1_rule
- STIG-ID|VCWN-06-000018
- Vuln-ID|V-63973