Testing the effect of interface manipulation on the values of IFF_UP and IFF_RUNNING.

Links:

• operstates.txt

From include/uapi/linux/if.h:

enum net_device_flags {
/* for compatibility with glibc net/if.h */
#if __UAPI_DEF_IF_NET_DEVICE_FLAGS
        IFF_UP                          = 1<<0,  /* sysfs */
        IFF_BROADCAST                   = 1<<1,  /* volatile */
        IFF_DEBUG                       = 1<<2,  /* sysfs */
        IFF_LOOPBACK                    = 1<<3,  /* volatile */
        IFF_POINTOPOINT                 = 1<<4,  /* volatile */
        IFF_NOTRAILERS                  = 1<<5,  /* sysfs */
        IFF_RUNNING                     = 1<<6,  /* volatile */
        IFF_NOARP                       = 1<<7,  /* sysfs */
        IFF_PROMISC                     = 1<<8,  /* sysfs */
        IFF_ALLMULTI                    = 1<<9,  /* sysfs */
        IFF_MASTER                      = 1<<10, /* volatile */
        IFF_SLAVE                       = 1<<11, /* volatile */
        IFF_MULTICAST                   = 1<<12, /* sysfs */
        IFF_PORTSEL                     = 1<<13, /* sysfs */
        IFF_AUTOMEDIA                   = 1<<14, /* sysfs */
        IFF_DYNAMIC                     = 1<<15, /* sysfs */
#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS */
#if __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
        IFF_LOWER_UP                    = 1<<16, /* volatile */
        IFF_DORMANT                     = 1<<17, /* volatile */
        IFF_ECHO                        = 1<<18, /* volatile */
#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
};