to ADDRESS (default)
-- the prefix selecting the neighbours to list.
dev NAME
-- only list the neighbours attached to this device.
unused
-- only list neighbours which are not currently in use.
nud NUD_STATE
-- only list neighbour entries in this state. NUD_STATE takes
values listed below or the special value all which means all states.
This option may occur more than once. If this option is absent, ip
lists all entries except for none and noarp.