remote internet address, expected to point to a sin_addr or sin6_addr instance, depending on the IP version of this instance
0 on success or -1 on failure. On error failure 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 per‐ mission is denied for one of the directories in the path pre‐ fix. (See also path_resolution(7).)
EACCES, EPERM The user tried to connect to a broadcast address without hav‐ ing 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.
EAGAIN No more free local ports or insufficient entries in the rout‐ ing cache. For AF_INET see the description of /proc/sys/net/ipv4/ip_local_port_range ip(7) for information on how to increase the number of local ports.
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 com‐ pleted 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 unsuc‐ cessfully (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.
Connects this socket the specified address and port.
Note: This generic wrapper should be used only in special situations, the subclass variants for a particular address family are preferred.
If this socket is of type SOCK_DGRAM then the address is the one 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() 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 (supported on Linux since kernel 2.2).