title: mosquitto-client obtain refused connection
body: <p>I want to use MQTT protocol using mosquitto library. </p>
  
  <p>First of all, I want to do some test installing mosquitto-clients</p>
  
  <pre><code> sudo apt-get install mosquitto-clients
  </code></pre>
  
  <p>This program provides two "method":</p>
  
  <ul>
  <li>mosquitto_pub</li>
  <li>mosquitto_sub</li>
  </ul>
  
  <p>Following <a href="http://michaelconnors.net/article/462/hello-mqtt" rel="noreferrer"><strong>this</strong></a> instructions I'm trying to submit new topic:</p>
  
  <pre><code>mosquitto_sub -d -t newtopic/test
  </code></pre>
  
  <p>using default host/port [localhost/1883].</p>
  
  <p>I obtain:</p>
  
  <pre><code>Error: Connection refused
  </code></pre>
  
  <p>Is too generic as error.. can anyone help me?<br>
  Could be is a firewall problem? In this case, how can I check if is this the problem?</p>
  
  <p>I'm using linux ubuntu ( 3.8.0-42-generic #62~precise1-Ubuntu)</p>
  
  <p><strong>nb</strong> same behaviour writing custom program using libmosquitto. </p>