CONNECT(2)						     Linux Programmer's Manual							CONNECT(2)

NAME

       connect - initiate a connection on a socket

SYNOPSIS

       #include <sys/types.h>	       /* See NOTES */
       #include <sys/socket.h>

       int connect(int sockfd, const struct sockaddr *addr,
		   socklen_t addrlen);

DESCRIPTION

       The  connect()  system  call  connects  the socket referred to by the file descriptor sockfd to the address specified by addr.  The addrlen
       argument specifies the size of addr.  The format of the address in addr is determined by the  address  space  of  the  socket  sockfd;  see
       socket(2) for further details.

       If the socket sockfd is of type SOCK_DGRAM then addr is the address to which datagrams are sent by default, and the only address from which
       datagrams are received.	If the socket is of type SOCK_STREAM or SOCK_SEQPACKET, this call attempts to make a connection to the socket that
       is bound to the address specified by addr.

       Generally, connection-based protocol sockets may successfully connect() only once; connectionless protocol sockets may use connect() multi-
       ple times to change their association.  Connectionless sockets may dissolve the association by connecting to an address with the  sa_family
       member of sockaddr set to AF_UNSPEC (supported on Linux since kernel 2.2).

RETURN VALUE

       If the connection or binding succeeds, zero is returned.  On error, -1 is returned, and errno is set appropriately.

ERRORS

       The following are general socket errors only.  There may be other domain-specific error codes.

       EACCES For  UNIX  domain  sockets, which are identified by pathname: Write permission is denied on the socket file, or search permission is
	      denied for one of the directories in the path prefix.  (See also path_resolution(7).)

       EACCES, EPERM
	      The user tried to connect to a broadcast address without having the socket broadcast flag enabled or the connection  request  failed
	      because of a local firewall rule.

       EADDRINUSE
	      Local address is already in use.

       EAFNOSUPPORT
	      The passed address didn't have the correct address family in its sa_family field.

       EADDRNOTAVAIL
	      Non-existent interface was requested or the requested address was not local.

       EALREADY
	      The socket is nonblocking and a previous connection attempt has not yet been completed.

       EBADF  The file descriptor is not a valid index in the descriptor table.

       ECONNREFUSED
	      No-one listening on the remote address.

       EFAULT The socket structure address is outside the user's address space.

       EINPROGRESS
	      The socket is nonblocking and the connection cannot be completed immediately.  It is possible to select(2) or poll(2) for completion
	      by selecting the socket for writing.  After select(2) indicates writability, use getsockopt(2) to read the SO_ERROR option at  level
	      SOL_SOCKET  to determine whether connect() completed successfully (SO_ERROR is zero) or unsuccessfully (SO_ERROR is one of the usual
	      error codes listed here, explaining the reason for the failure).

       EINTR  The system call was interrupted by a signal that was caught; see signal(7).

       EISCONN
	      The socket is already connected.

       ENETUNREACH
	      Network is unreachable.

       ENOTSOCK
	      The file descriptor is not associated with a socket.

       ETIMEDOUT
	      Timeout while attempting connection.  The server may be too busy to accept new connections.  Note that for IP  sockets  the  timeout
	      may be very long when syncookies are enabled on the server.

CONFORMING TO

       SVr4, 4.4BSD, (the connect() function first appeared in 4.2BSD), POSIX.1-2001.

NOTES

       POSIX.1-2001  does  not	require  the  inclusion of <sys/types.h>, and this header file is not required on Linux.  However, some historical
       (BSD) implementations required this header file, and portable applications are probably wise to include it.

       The third argument of connect() is in reality an int (and this is what 4.x BSD and libc4 and libc5 have).  Some POSIX confusion resulted in
       the present socklen_t, also used by glibc.  See also accept(2).

EXAMPLE

       An example of the use of connect() is shown in getaddrinfo(3).

SEE ALSO

       accept(2), bind(2), getsockname(2), listen(2), socket(2), path_resolution(7)

COLOPHON

       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2008-12-03								CONNECT(2)