public function connect()
    {
        if ( ! ($this->connection = ssh2_connect($this->host, $this->port))) {
            throw new \Exception('Cannot connect to server');
        }
        
        if ( ! ssh2_auth_pubkey_file($this->connection, $this->authUser, $this->authPub, $this->authPriv,
            $this->authPass)
        ) {
            throw new \Exception('Autentication rejected by server');
        }
    }