This function manipulates options associated with a socket.
    Options can exist at multiple protocol levels. They are always
    present at the uppermost socket level.
    When manipulating socket options, specify the level at which the
    option resides and the name of the option. To manipulate options
    at the socket level, specify the value of level as SOL_SOCKET. To
    manipulate options at any other level, supply the protocol number
    of the appropriate protocol controlling the option. For example,
    to indicate that an option is to be interpreted by TCP, set the
    value for the level argument to the protocol number (IPPROTO_TCP)
    of TCP.
    For IPv4, see the IN.H header file for the various IPPROTO
    values. For IPv6, see the IN6.H header file for the various
    IPPROTO_IPV6 values.