VMS Help TCPIP Services, Programming Interfaces, Sockets API, getprotobynumber()  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Searches the protocols database until a matching protocol number
    is found or until end of file is encountered.
    Format
      #include  <netdb.h>
      struct protoent *getprotobynumber  ( int *proto) ;

1 - Argument

 proto
    A pointer to a string containing the desired protocol number.

2 - Description

    This function returns a pointer to a protoent structure
    containing the data from the protocols database:
    struct  protoent {
            char   *p_name;       /* official name of protocol */
            char   **p_aliases;   /* alias list */
            long   p_proto;       /* protocol number */
    };
    The members of this structure are:
    p_name             The official name of the protocol.
    p_aliases          A zero-terminated list of alternate names for
                       the protocol.
    p_proto            The protocol number.
    All information is contained in a static area, so it must be
    copied to be saved.
    Related Functions
    See also getprotoent() and getprotobyname().

3 - Return Values

    NULL               Indicates end of file or an error.
    x                  A pointer to a protoent structure.