title: cannot open url made by using rails server on cloud9IDE
body: <p>I wanna open the url made by using rails server on cloud9IDE.So i try <code>rails s -b $IP -p $PORT</code> to run, and rails server is running, but when open url <code>http://tcp://0.0.0.0:8080</code>, the server cannot detected.</p>
  
  <p>Could you help me?</p>
  
  <pre><code>$ rails s -b 0.0.0.0 -p 8080
  =&gt; Booting Puma
  =&gt; Rails 5.1.6 application starting in development 
  =&gt; Run `rails server -h` for more startup options
  Puma starting in single mode...
  * Version 3.9.1 (ruby 2.4.1-p111), codename: Private Caller
  * Min threads: 5, max threads: 5
  * Environment: development
  * Listening on tcp://0.0.0.0:8080
  Use Ctrl-C to stop
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/fv5ll.png" rel="nofollow noreferrer">not detected img</a></p>