def pbm(self):
        """ Plumbum lazy property """
        if not self.disable_rpyc:
            from plumbum import SshMachine
            return SshMachine(host=self.private_hostname, user=self.username,
                              keyfile=self.key_filename,
                              ssh_opts=["-o", "UserKnownHostsFile=/dev/null",
                                        "-o", "StrictHostKeyChecking=no"])
        else:
            return None