This function returns a pointer to a protoent structure
    containing the data from the protocols table. For information
    about the protoent structure, refer to protoent Structure.
    The getprotoent() function keeps an index to the table, allowing
    successive calls to be used to search the entire table.
    All information is contained in a static area, so it must be
    copied to be saved.
    Related Functions
    See also getprotobyname() and getprotobynumber().