ifconfig eth2 lladdr A:B:C:1:2:3

     lladdr addr
             Set the link-level address on an interface.  This can be used to
             e.g. set a new MAC address on an ethernet interface, though the
             mechanism used is not ethernet-specific.  The address addr is
             specified as a series of colon-separated hex digits.  If the
             interface is already up when this option is used, it will be
             briefly brought down and then brought back up again in order to
             ensure that the receive filter in the underlying ethernet hard-
             ware is properly reprogrammed.

SIOCSIFHWADDR: Demasiados archivos abiertos en el sistema