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BINDRESVPORT(3)                         BSD Library Functions Manual                         BINDRESVPORT(3)

NAME
     bindresvport, bindresvport_sa -- bind a socket to a privileged IP port

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <rpc/rpc.h>

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

     int
     bindresvport_sa(int sd, struct sockaddr *sa);

DESCRIPTION
     The bindresvport() and bindresvport_sa() functions are used to bind a socket descriptor to a privileged
     IP port, that is, a port number in the range 0-1023.

     If sin is a pointer to a struct sockaddr_in then the appropriate fields in the structure should be
     defined.  Note that sin->sin_family must be initialized to the address family of the socket, passed by
     sd.  If sin->sin_port is `0' then an anonymous port (in the range 600-1023) will be chosen, and if
     bind(2) is successful, the sin->sin_port will be updated to contain the allocated port.

     If sin is the NULL pointer, an anonymous port will be allocated (as above).  However, there is no way
     for bindresvport() to return the allocated port in this case.

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

     Function prototype of bindresvport() is biased to AF_INET socket.  The bindresvport_sa() function acts
     exactly the same, with more neutral function prototype.  Note that both functions behave exactly the
     same, and both support AF_INET6 sockets as well as AF_INET sockets.

RETURN VALUES
     The bindresvport() function returns the value 0 if successful; otherwise the value -1 is returned and
     the global variable errno is set to indicate the error.

ERRORS
     [EPFNOSUPPORT]     If second argument was supplied, and address family did not match between arguments.

     The bindresvport() function may also fail and set errno for any of the errors specified for the calls
     bind(2), getsockopt(2), or setsockopt(2).

SEE ALSO
     bind(2), getsockopt(2), setsockopt(2), ip(4)

BSD                                           November 22, 1987                                          BSD