title: Why is Django throwing error "DisallowedHost at /"?
body: <p>I am setting up my own Django server using this <a href="https://www.digitalocean.com/community/tutorials/how-to-set-up-django-with-postgres-nginx-and-gunicorn-on-ubuntu-14-04" rel="noreferrer">Digital Ocean tutorial</a>. I created the Django framework following each step, and ran the server using this command:</p>
  
  <pre><code>./manage.py runserver 0.0.0.0:8000
  </code></pre>
  
  <p>When I tried to visit the IP at port 8000, the following error was shown:</p>
  
  <pre><code>DisallowedHost at /
  Invalid HTTP_HOST header: 'XXX.XXX.XXX.XXX:8000'. You may need to add u'XXX.XXX.XXX.XXX' to ALLOWED_HOSTS.
  </code></pre>
  
  <p>(IP substituted with X's)</p>
  
  <p>Why is this happening?</p>