If specified, request that the device use this MAC address instead.
This is known as MAC cloning or spoofing.
Beside explicitly specifying a MAC address, the special values "preserve", "permanent", "random" and "stable" are supported. "preserve" means not to touch the MAC address on activation. "permanent" means to use the permanent hardware address of the device. "random" creates a random MAC address on each connect. "stable" creates a hashed MAC address based on connection.stable-id and a machine dependent key.
If unspecified, the value can be overwritten via global defaults, see manual of NetworkManager.conf. If still unspecified, it defaults to "preserve" (older versions of NetworkManager may use a different default value).
On D-Bus, this field is expressed as "assigned-mac-address" or the deprecated "cloned-mac-address".