title: Node.js + Express: app won't start listening on port 80
body: <p>I create and launch an app like this:</p>
  
  <pre><code>express -s -t ejs
  npm install express
  npm install ejs
  node app.js
  </code></pre>
  
  <p>and it works (on port 3000). But when I go and change the port to 80, then running <code>node app.js</code> outputs this:</p>
  
  <pre><code>node.js:198
  throw e; // process.nextTick error, or 'error' event on first tick
            ^
  TypeError: Cannot call method 'getsockname' of null
  at HTTPServer.address (net.js:746:23)
  at Object.&lt;anonymous&gt; (/var/www/thorous/app.js:35:67)
  at Module._compile (module.js:432:26)
  at Object..js (module.js:450:10)
  at Module.load (module.js:351:31)
  at Function._load (module.js:310:12)
  at Array.&lt;anonymous&gt; (module.js:470:10)
  at EventEmitter._tickCallback (node.js:190:26)
  </code></pre>
  
  <p>This works too on my laptop, but not on my Amazon EC2 instance, where port 80 is open.
  Can figure out what's wrong. Any tips?</p>