无法从套接字io应用连接到远程Redis机器

Question

在尝试使用Redis连接多个套接字io节点时，我的Redis机器与应用程序分离，我必须提供用户名和密码才能访问它，我当前的代码如下所示：

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);

var redis = require('redis');
var redisAdapter = require('socket.io-redis');

var pub = redis.createClient('redis://{username}:{password}@{hostname}:{port}');
var sub = redis.createClient('redis://{username}:{password}@{hostname}:{port}');
io.adapter(redisAdapter({ pubClient: pub, subClient: sub }));

var port = process.env.PORT || 3000;

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

我遇到以下错误：

listening on *:3000
events.js:183
      throw er; // Unhandled 'error' event
      ^

Error: Redis connection to node********.com:6379 failed - connect ETIMEDOUT 109.109.136.70:6379
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1191:14)

对此我该怎么办？