Need a random MAC address quickly? With the virtinst package from Ubuntu, or the python-virtinst package in CentOS, simply do this in your code:

import virtinst.util
print virtinst.util.randomMAC()

Or from the command line:

$ echo 'import virtinst.util; print virtinst.util.randomMAC()' | python
00:16:3e:a7:08:18