include <netinet/in.h>

     int
     bindresvport(int sd, struct sockaddr_in **sin);

DESCRIPTION

     bindresvport() is used to bind a socket descriptor to a privileged IP
     port, that is, a port number in the range 0-1023.  The routine returns 0
     if it is successful, otherwise -1 is returned and errno set to reflect
     the cause of the error.

     Only root can bind to a privileged port; this call will fail for any
     other users.

     If the value of sin->sin_port is non-zero bindresvport() otherwise it
     attempts to use the specified port.  If that fails, it chooses another
     privileged port number automatically.

BSD                            November 22, 1987                           BSD