private static String randomMACAddress(){
	    Random rand = new Random();
	    byte[] macAddr = new byte[6];
	    rand.nextBytes(macAddr);

	    macAddr[0] = (byte)(macAddr[0] & (byte)254);  //zeroing last 2 bytes to make it unicast and locally adminstrated

	    StringBuilder sb = new StringBuilder(18);
	    for(byte b : macAddr){

	        if(sb.length() > 0)
	            sb.append(":");

	        sb.append(String.format("%02x", b));
	    }


	    return sb.toString();
	}