Gets information on the specified port from the services database
    that is referenced by the TCPIP$SERVICE logical name. If the
    specified port is not found, this function may invoke the BIND
    resolver to search TCPIP$ETC:SERVICES.DAT.
    Format
      #include  <netdb.h>
      struct servent *getservbyport  ( int port, char *proto );

1  –  Arguments

 port
    The port number for which to search. This port number should be
    specified in network byte order. You can use the htons() function
    to convert the port number to network byte order.
 proto
    A pointer to a string containing the name of the protocol (TCP or
    UDP) for which to search.

2  –  Description

    This function searches the services database until a matching
    port is found, or until end of file is encountered. If a protocol
    name is also supplied, searches must also match the protocol.
    This function returns a pointer to a servent structure containing
    the broken-out fields of the requested line in the network
    services database. For information about the servent structure,
    refer to servent Structure.
    All information is contained in a static area, so it must be
    copied to be saved.
    Related Functions
    See also getservbyname().

3  –  Return Values

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

4  –  Errors

    EPERM              Not owner. Indicates that the wrong port
                       number was specified.