When you issue the ifconfig command for an interface you might
    see any of the following options displayed:

    BROADCAST  The interface supports broadcast packets. This is a
               read-only option that is set by the driver.
    LOOPBACK   The interface is a loopback mode. Packets transmitted
               on this interface will be looped back in the driver and
               not be transmitted out on the network.
    MULTICAST  The interface supports multicast packets. This is a
               read-only option that is set by the driver and does
               not mean that a multicast address is configured for the
               interface.
    NOARP      The interface is not using address resolution protocol
               (ARP). It will neither transmit nor respond to ARP
               requests.
    NOCHECKSUM The interface does not perform checksums on transmitted
               or received packets. Use this option only on very
               reliable network media.
    POINTOPOINTThe interface is point-to-point link. This is a read-
               only option that is set by the driver.
    RUNNING    The driver has allocated resources for the interface,
               and is ready to transmit and receive packets. This is a
               read-only option that is set by the driver. It is not
               applicable to loopback devices.
    SIMPLEX    The interface cannot receive its own transmissions.
               This is a read-only option that is set by the driver.