def load_connection_file(self):
        """load ip/port/hmac config from JSON connection file"""
        try:
            fname = filefind(self.connection_file, ['.', self.profile_dir.security_dir])
        except IOError:
            self.log.debug("Connection file not found: %s", self.connection_file)
            # This means I own it, so I will clean it up:
            atexit.register(self.cleanup_connection_file)
            return
        self.log.debug(u"Loading connection file %s", fname)
        with open(fname) as f:
            s = f.read()
        cfg = json.loads(s)
        if self.ip == LOCALHOST and 'ip' in cfg:
            # not overridden by config or cl_args
            self.ip = cfg['ip']
        for channel in ('hb', 'shell', 'iopub', 'stdin'):
            name = channel + '_port'
            if getattr(self, name) == 0 and name in cfg:
                # not overridden by config or cl_args
                setattr(self, name, cfg[name])
        if 'key' in cfg:
            self.config.Session.key = str_to_bytes(cfg['key'])
load ip/port/hmac config from JSON connection file