This function creates an unbound pair of connected sockets in a
    specified address family, of a specified type, under the protocol
    optionally specified by the protocol argument. The two sockets
    will be identical. The file descriptors used in referencing the
    created sockets are returned in socket_vector[0] and socket_
    vector[1].
    Appropriate privileges are required to use the socketpair()
    function or to create some sockets.
    Related Functions
    See also socket().