Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
BIND(2)			  FreeBSD System Calls Manual		       BIND(2)

NAME
     bind -- bind a name to a socket

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/socket.h>

     int
     bind(int s, const struct sockaddr *name, socklen_t	namelen);

DESCRIPTION
     bind() assigns a name to an unnamed socket.  When a socket	is created
     with socket(2) it exists in a name	space (address family) but has no name
     assigned.	bind() requests	that name be assigned to the socket.  namelen
     indicates the amount of space pointed to by name, in bytes.

NOTES
     Binding a name in the UNIX	domain creates a socket	in the file system
     that must be deleted by the caller	when it	is no longer needed (using
     unlink(2)).

     The rules used in name binding vary between communication domains.	 Con-
     sult the manual entries in	section	4 for detailed information.

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
     The bind()	call will fail if:

     [EACCES]		The requested address is protected, and	the current
			user has inadequate permission to access it.

     [EADDRINUSE]	The specified address is already in use.

     [EADDRNOTAVAIL]	The specified address is not available from the	local
			machine.

     [EAFNOSUPPORT]	Addresses in the specified address family cannot be
			used with this socket.

     [EBADF]		s is not a valid descriptor.

     [EFAULT]		The name parameter is not in a valid part of the user
			address	space.

     [EINVAL]		The socket is already bound to an address; or the fam-
			ily of the socket and that requested in
			name-_sa_family	are not	equivalent.

     [ENOTSOCK]		s is not a socket.

     The following errors are specific to binding names	in the UNIX domain.

     [EIO]		An I/O error occurred while making the directory entry
			or allocating the inode.

     [EISDIR]		An empty pathname was specified.

     [ELOOP]		Too many symbolic links	were encountered in translat-
			ing the	pathname.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} charac-
			ters, or an entire path	name exceeded {PATH_MAX} char-
			acters.

     [ENOENT]		A prefix component of the path name does not exist.

     [ENOTDIR]		A component of the path	prefix is not a	directory.

     [EROFS]		The name would reside on a read-only file system.

SEE ALSO
     connect(2), getsockname(2), listen(2), socket(2)

HISTORY
     The bind()	function call appeared in 4.2BSD.

SECURITY CONSIDERATIONS
     bind() was	changed	in NetBSD 1.4 to prevent the binding of	a socket to
     the same port as an existing socket when all of the following is true:
	   +o   either of the existing or new addresses is INADDR_ANY,
	   +o   the uid of the new socket is not	root, and the uids of the cre-
	       ators of	the sockets are	different,
	   +o   the address is not a multicast address, and
	   +o   both sockets are	not bound to INADDR_ANY	with SO_REUSEPORT set.

     This prevents an attack where a user could	bind to	a port with the	host's
     IP	address	(after setting SO_REUSEADDR) and `steal' packets destined for
     a server that bound to the	same port with INADDR_ANY.

     bind() was	changed	in NetBSD 4.0 to honor the user's umask	when binding
     sockets in	the local domain.  This	was done to match the behavior of
     other operating systems, including	FreeBSD, OpenBSD, and Linux, and to
     improve compatibility with	some third-party software.  Please note	that
     this behavior is not portable.  If	you must bind a	local socket in	a por-
     table and secure way, you need to make a directory	with tight permissions
     and then create the socket	inside it.

FreeBSD	13.0			 April 5, 2015			  FreeBSD 13.0

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | ERRORS | SEE ALSO | HISTORY | SECURITY CONSIDERATIONS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=bind&sektion=2&manpath=NetBSD+9.1>

home | help