HP-UX

ant:/home/vbe $ ndd -h socket_udp_sndbuf_default

socket_udp_sndbuf_default:

    Sets the default send buffer size for UDP sockets.
    [1-65535] Default: 65535

ant:/home/vbe $ ndd -h socket_udp_rcvbuf_default

socket_udp_rcvbuf_default:

    Sets the default receive buffer size for UDP sockets.
    The value of this tunable parameter should not exceed the
    value of the ndd parameter udp_recv_hiwater_max. Otherwise,
    a socket() call to create UDP socket will fail and return 
    the errno value EINVAL.
    [1-2147483647] Default: 65535