title: RabbitMQ Cluster : unable to connect to nodes : nodedown
body: <p>I have installed rabbitmq in two machines in linux OS.And they all worked well. Then I run the command:rabbitmqctl join_cluster rabbit@gz2, it's not work.And the error info :</p>
  
  <p>Error: unable to connect to nodes [rabbit@gz2]: nodedown</p>
  
  <p>attempted to contact: [rabbit@gz2]</p>
  
  <p>rabbit@gz2:</p>
  
  <ul>
  <li>connected to epmd (port 4369) on gz2</li>
  <li>epmd reports node 'rabbit' running on port 25672</li>
  <li>TCP connection succeeded but Erlang distribution failed</li>
  <li>suggestion: hostname mismatch?</li>
  <li>suggestion: is the cookie set correctly?</li>
  <li>suggestion: is the Erlang distribution using TLS?</li>
  </ul>