Command Section
CONNECT(2)                FreeBSD System Calls Manual               CONNECT(2)

     connect - initiate a connection on a socket

     Standard C Library (libc, -lc)

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

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

     The s argument is a socket.  If it is of type SOCK_DGRAM, this call
     specifies the peer with which the socket is to be associated; this
     address is that to which datagrams are to be sent, and the only address
     from which datagrams are to be received.  If the socket is of type
     SOCK_STREAM, this call attempts to make a connection to another socket.
     The other socket is specified by name, which is an address in the
     communications space of the socket.  namelen indicates the amount of
     space pointed to by name, in bytes; the sa_len member of name is ignored.
     Each communications space interprets the name argument in its own way.
     Generally, stream sockets may successfully connect() only once; datagram
     sockets may use connect() multiple times to change their association.
     Datagram sockets may dissolve the association by connecting to an invalid
     address, such as a null address.

     The connect() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the

     The connect() system call fails if:

     [EBADF]            The s argument is not a valid descriptor.

     [EINVAL]           The namelen argument is not a valid length for the
                        address family.

     [ENOTSOCK]         The s argument is a descriptor for a file, not a

     [EADDRNOTAVAIL]    The specified address is not available on this

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

     [EISCONN]          The socket is already connected.

     [ETIMEDOUT]        Connection establishment timed out without
                        establishing a connection.

     [ECONNREFUSED]     The attempt to connect was forcefully rejected.

     [ECONNRESET]       The connection was reset by the remote host.

     [ENETUNREACH]      The network is not reachable from this host.

     [EHOSTUNREACH]     The remote host is not reachable from this host.

     [EADDRINUSE]       The address is already in use.

     [EFAULT]           The name argument specifies an area outside the
                        process address space.

     [EINPROGRESS]      The socket is non-blocking and the connection cannot
                        be completed immediately.  It is possible to select(2)
                        for completion by selecting the socket for writing.

     [EINTR]            The connection attempt was interrupted by the delivery
                        of a signal.  The connection will be established in
                        the background, as in the case of EINPROGRESS.

     [EALREADY]         A previous connection attempt has not yet been

     [EACCES]           An attempt is made to connect to a broadcast address
                        (obtained through the INADDR_BROADCAST constant or the
                        INADDR_NONE return value) through a socket that does
                        not provide broadcast functionality.

     [EAGAIN]           An auto-assigned port number was requested but no
                        auto-assigned ports are available.  Increasing the
                        port range specified by sysctl(3) MIB variables
                        net.inet.ip.portrange.first and
                        net.inet.ip.portrange.last may alleviate the problem.

     The following errors are specific to connecting names in the UNIX domain.
     These errors may not apply in future versions of the UNIX IPC domain.

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

     [ENAMETOOLONG]     A component of a pathname exceeded 255 characters, or
                        an entire path name exceeded 1023 characters.

     [ENOENT]           The named socket does not exist.

     [EACCES]           Search permission is denied for a component of the
                        path prefix.

     [EACCES]           Write access to the named socket is denied.

     [ELOOP]            Too many symbolic links were encountered in
                        translating the pathname.

     [EPERM]            Write access to the named socket is denied.

     accept(2), getpeername(2), getsockname(2), select(2), socket(2),
     sysctl(3), sysctl(8)

     The connect() system call appeared in 4.2BSD.

FreeBSD 11.1-RELEASE-p4        February 4, 2016        FreeBSD 11.1-RELEASE-p4
Command Section