title: Disallowing login for "inactive" users in Symfony2
body: <p>I set up my app's authentication system based on the <a href="http://symfony.com/doc/current/book/security.html" rel="noreferrer">Symfony2 security documentation</a>.</p>
  
  <p>Each one of my users has an <code>active</code> flag. I don't want users whose <code>active</code> = false to be able to log in.</p>
  
  <p>I don't really understand where the logic is that says whether or not a user is allowed to log in, so I'm somewhat at a loss as to how to accomplish this. Can someone please steer me in the right direction?</p>