title: not able to connect to test.mosquitto.org
body: <p>I am working on esp8266 and trying to connect to test.mosquitto.org.
  here is what I got from net</p>
  
  <pre><code>m = mqtt.Client("clientid", 60, "user", "password")
  m:on("connect", function(con) print ("connected") end)
  m:on("offline", function(con) print ("offline") end)
  m:on("message", function(conn, topic, data) 
    print(topic .. ":" ) 
    if data ~= nil then
      print(data)
    end
  end)
  
  m:connect("http://test.mosquitto.org/", 1883, 0, function(conn) print("connected") end)
  m:subscribe("/topic",0, function(conn) print("subscribe success") end)
  m:publish("/topic","hello",0,0, function(conn) print("sent") end)
  m:close();
  </code></pre>
  
  <p>I am not sure from where to get clientId ,user and pass,</p>
  
  <p>here what I am getting :
  DNS retry 1!
  DNS retry 2!
  DNS retry 3!
  DNS retry 4!
  DNS Fail!</p>