title: hadoop slave cannot connect to master:8031
body: <p>I'm a total hadoop newbee. I set up hadoop on two machines master and slave following <a href="http://www.michael-noll.com/tutorials/running-hadoop-on-ubuntu-linux-multi-node-cluster/" rel="nofollow noreferrer">this tutorial</a> (I obtained the same error following <a href="https://chawlasumit.wordpress.com/2015/03/09/install-a-multi-node-hadoop-cluster-on-ubuntu-14-04/" rel="nofollow noreferrer">this other tutorial</a>).</p>
  
  <p><strong>Problem</strong>: After starting dfs and yarn, the only node appearing on localhost:50070 is the master, even if the right processes are running on the master (NameNode, DataNode, SecondaryNameNode, ResourceManager) and on the slave (DataNode). </p>
  
  <p>The nodemanager log of the slave reports: <em>INFO org.apache.hadoop.ipc.Client: Retrying connect to server: master/192.168.0.14:8031. Already tried 10 times</em>.</p>
  
  <p>Note that:</p>
  
  <ol>
  <li>I have already edited yarn-site.xml following <a href="https://stackoverflow.com/questions/20620949/yarn-resourcemanager-not-connecting-to-nodemanager">this thread</a>.</li>
  <li>I have disabled the firewall on the master</li>
  <li>I ran <em>netstat -anp | grep 8031</em> on the master and confirmed that there are a couple of processes listening on port 8031 using tcp.</li>
  </ol>