.\" $OpenBSD: bindresvport.3,v 1.11 1999/07/09 13:35:22 aaron Exp $ .\" .Dd August 9, 1997 .Dt BINDRESVPORT 3 .Os .Sh NAME .Nm bindresvport .Nd bind a socket to a privileged IP port .Sh SYNOPSIS .Fd #include .Fd #include .Ft int .Fn bindresvport "int sd" "struct sockaddr_in *sin" .Sh DESCRIPTION .Fn bindresvport is used to bind a socket descriptor to a privileged .Tn IP port, that is, a port number in the range 0-1023. .Fa sd is a socket descriptor that was returned by a call to .Xr socket 2 . .Pp Only root can bind to a privileged port; this call will fail for any other users. .Pp If the value of sin->sin_port is non-zero, .Fn bindresvport attempts to use the specified port. If that fails, it chooses another privileged port number automatically. .Sh RETURN VALUES .Fn bindresvport returns 0 if it is successful, otherwise \-1 is returned and .Va errno set to reflect the cause of the error. .Sh ERRORS The .Fn bindresvport function fails if: .Bl -tag -width Er .It Bq Er EBADF .Fa sd is not a valid descriptor. .It Bq Er ENOTSOCK .Fa sd is not a socket. .It Bq Er EADDRNOTAVAIL The specified address is not available from the local machine. .It Bq Er EADDRINUSE The specified address is already in use. .It Bq Er EINVAL The socket is already bound to an address. .It Bq Er EACCES The requested address is protected, and the current user has inadequate permission to access it. .It Bq Er EFAULT The .Fa name parameter is not in a valid part of the user address space. .It Bq Er ENOBUFS Insufficient resources were available in the system to perform the operation. .It Bq Er EPFNOSUPPORT The protocol family has not been configured into the system or no implementation for it exists. .El .Sh SEE ALSO .Xr bind 2 , .Xr socket 2 , .Xr rresvport 3