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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 <&lt;sys/types.h>&gt;
     #include <&lt;rpc/rpc.h>&gt;

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

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

DESCRIPTION
     bindresvport() and bindresvport_sa() are 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.

     If sin is a pointer to a struct sockaddr_in then the appropriate fields
     in the structure should be defined.  Note that sin-&gt;sin_family must be
     initialized to the address family of the socket, passed by sd.  If
     sin-&gt;sin_port is '0' then an anonymous port (in the range 600-1023) will
     be chosen, and if bind(2) is successful, the sin-&gt;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 allo-
     cated 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.
     bindresvport_sa() acts exactly the same, with more neutral function pro-
     totype.  Note that both functions behave exactly the same, and both sup-
     port AF_INET6 sockets as well as AF_INET sockets.

RETURN VALUES
     If the bind is successful, a 0 value is returned.  A return value of -1
     indicates an error, which is further specified in the global errno.

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

     bindresvport() may also fail and set errno for any of the errors speci-
     fied 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