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RedHat 9 (Linux i386) - man page for connect (redhat section 2)

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

NAME
       connect - initiate a connection on a socket

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

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

DESCRIPTION
       The  file  descriptor  sockfd must refer to a socket.  If the socket is of type SOCK_DGRAM
       then the serv_addr address 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  another  socket.   The  other
       socket  is specified by serv_addr, which is an address (of length addrlen) in the communi-
       cations space of the socket.  Each communications space interprets the serv_addr parameter
       in its own way.

       Generally,  connection-based  protocol sockets may successfully connect only once; connec-
       tionless protocol sockets may use connect multiple  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.

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.

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

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

       ENOTSOCK
	      The file descriptor is not associated with a socket.

       EISCONN
	      The socket is already connected.

       ECONNREFUSED
	      No one listening on the remote address.

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

       ENETUNREACH
	      Network is unreachable.

       EADDRINUSE
	      Local address is already in use.

       EINPROGRESS
	      The socket is non-blocking 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 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).

       EALREADY
	      The  socket is non-blocking and a previous connection attempt has not yet been com-
	      pleted.

       EAGAIN No more free local ports or insufficient entries in the routing cache. For  PF_INET
	      see  the net.ipv4.ip_local_port_range sysctl in ip(7) on how to increase the number
	      of local ports.

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

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

CONFORMING TO
       SVr4, 4.4BSD (the connect function first appeared in BSD 4.2).  SVr4 documents  the  addi-
       tional  general	error codes EADDRNOTAVAIL, EINVAL, EAFNOSUPPORT, EALREADY, EINTR, EPROTO-
       TYPE, and ENOSR.  It also documents many additional error conditions not described here.

NOTE
       The third argument of connect is in reality an int (and this is what BSD 4.* and libc4 and
       libc5  have).  Some POSIX confusion resulted in the present socklen_t.  The draft standard
       has not been adopted yet, but glibc2 already follows it and also has socklen_t.	See  also
       accept(2).

BUGS
       Unconnecting a socket by calling connect with a AF_UNSPEC address is not yet implemented.

SEE ALSO
       accept(2), bind(2), listen(2), socket(2), getsockname(2)

Linux 2.2				    1998-10-03				       CONNECT(2)


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