LIBSSH2_ERROR_SOCKET_NONE - The socket is invalid.
LIBSSH2_ERROR_BANNER_SEND - Unable to send banner to remote host.
LIBSSH2_ERROR_KEX_FAILURE - >Encryption key exchange with the remote
LIBSSH2_ERROR_SOCKET_SEND - Unable to send data on socket.
LIBSSH2_ERROR_SOCKET_DISCONNECT - The socket was disconnected.
LIBSSH2_ERROR_PROTO - An invalid SSH protocol response was received on
LIBSSH2_ERROR_EAGAIN - Marked for non-blocking I/O but the call would block.