Update SSH connection parameters based on contents of SSH 'config' file.

        :param dict_arg: Dictionary of SSH connection parameters
        :type dict_arg: dict

def _use_ssh_config(self, dict_arg):
        """Update SSH connection parameters based on contents of SSH 'config' file.

        :param dict_arg: Dictionary of SSH connection parameters
        :type dict_arg: dict
        """
        connect_dict = dict_arg.copy()

        # Use SSHConfig to generate source content.
        full_path = path.abspath(path.expanduser(self.ssh_config_file))
        if path.exists(full_path):
            ssh_config_instance = paramiko.SSHConfig()
            with io.open(full_path, "rt", encoding="utf-8") as f:
                ssh_config_instance.parse(f)
                source = ssh_config_instance.lookup(self.host)
        else:
            source = {}

        if "proxycommand" in source:
            proxy = paramiko.ProxyCommand(source["proxycommand"])
        elif "ProxyCommand" in source:
            proxy = paramiko.ProxyCommand(source["ProxyCommand"])
        else:
            proxy = None

        # Only update 'hostname', 'sock', 'port', and 'username'
        # For 'port' and 'username' only update if using object defaults
        if connect_dict["port"] == 22:
            connect_dict["port"] = int(source.get("port", self.port))
        if connect_dict["username"] == "":
            connect_dict["username"] = source.get("user", self.username)
        if proxy:
            connect_dict["sock"] = proxy
        connect_dict["hostname"] = source.get("hostname", self.host)

        return connect_dict