    @Test
    public void testGetMacAddr() {

        assertEquals("11:22:33:aa:bb:cc", SNMUtils.getMacAddr("xxx (192.168.178.1) at 11:22:33:aa:bb:cc [ether] on eth0"));
        assertEquals("11:22:33:aa:bb:cc", SNMUtils.getMacAddr("xxx (192.168.178.1) at 11:22:33:aa:bb:cc [ether] on eth0 aa:bb:cc:11:22:33"));
        assertEquals("", SNMUtils.getMacAddr("xxx (192.168.178.1) at  [ether] on eth0"));
        assertEquals("", SNMUtils.getMacAddr(""));
        assertEquals("", SNMUtils.getMacAddr(null));
    }