Manual MAC address for a VMware guest
If you’ve ever tried to manually specify a MAC address for a VMware ESX virtual machine, you might have encountered the error message:
The MAC address entered is not in the valid range. Valid values are between 00:50:56:00:00:00 and 00:50:56:3f:ff:ff.
The reasons why VMware force manual MAC addresses into this scope are unclear to me (probably to prevent collisions), but regardless, it can be an issue. I needed to specify a particular MAC address in the 00:04 range. The reason being we were retiring an old physical server running the FLEXlm licensing service and the licenses were granted for the MAC address of the NIC on that machine. Renewing the licenses for the new virtual machine turned out to be ridiculously expensive so our only real option was to “spoof” the MAC address.
I then ran into the aforementioned issue. However, the problem was easily solved by setting the MAC address from within the guest operating system instead. In this case, the server was running Windows Server 2003 and changing the MAC address was as simple as modifying the parameter “networkaddress” in the properties for the NIC in device manager. Voila!