title: add the rules to open a port using iptable, then the hadoop cluster does not working
body: <p>I am managing a 4-node hadoop cluster, which has 1 master node and 3 datanode, I am trying to open a port in master node, using the command below, the command is appended  to the /etc/sysconfig/iptables</p>
  
  <pre><code>-A INPUT -m state --state New -m tcp -p tcp --dport 1015 -j ACCEPT
  </code></pre>
  
  <p>Then, I save the iptables, and restart the iptables</p>
  
  <pre><code> /etc/init.d/iptables restart
  </code></pre>
  
  <p>Also restart the ipservice like below, then the data node can not communicate with master node anymore, even I try to revoke what I have done, would be appreciate if anyone can suggest so that I can re-use the Hadoop cluster since I have important data on it.</p>
  
  <pre><code>service iptables restart
  </code></pre>