I have some software running on a Windows virtual machine. I am using VMWare as the virtualization technology. The problem comes in with the software's activation / registration. The company who created the software is using the machine's MAC address to uniquely identify the machine during the process.

Whenever I reboot the VM image I get a new dynamic MAC address, which then causes the software to de-activate itself. Is there a way I can setup the VM image so that it will always use the same static MAC address?

  • Which VMWare product are you using? Workstation, Server, EX, EXi?
    – Brettski
    May 22, 2009 at 15:20
  • I have one machine with Server and another with Workstation. I've seen this happen on both.
    – Aaron K
    May 22, 2009 at 18:20

2 Answers 2


Short answer that glosses over the details; VMware will usually provide a unique MAC address for a VM on a network. It will usually provide the same MAC address to a VM so long as the VM is not moved between hosts. In circumstances where this a changing mac address is a problem, you can manually set one.

To manually assign an address, edit the config file for the VM; Remove


and add

ethernetN.address = 00:50:56:XX:YY:ZZ

XX must be a valid hexadecimal number between 00h and 3Fh, and YY and ZZ must be valid hexadecimal numbers between 00h and FFh

This is how it's done with Server, Workstation, and GSX (and I presume Fusion) The basics are the same for ESX, but what mac addresses you can use are different.

For more, search the VMware knowledge base for the articles

"Setting a static MAC address for a virtual NIC", "Changing the MAC Address of a virtual Machine" and other articles with "MAC Address" in their title.


Yes, but you have to edit the VM's config file directly via the COS, with the VM shutdown too (I think).

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