title: kafka broker not available at starting
body: <p>I set on a ubuntu node of a cluster a kafka 0.11.0.0 instance.
  Until some weeks ago everything worked fine, today I'm trying to starting it and I obtain this error after the boot:</p>
  
  <pre><code>[2017-09-11 16:21:13,894] INFO [Kafka Server 0], started (kafka.server.KafkaServer)
  [2017-09-11 16:21:18,998] WARN Connection to node 0 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
  [2017-09-11 16:21:21,991] WARN Connection to node 0 could not be established. Broker may not be available. (org.apache.kafka.clients.NetworkClient)
  ... and so on...
  </code></pre>
  
  <p>My server.properties:</p>
  
  <pre><code>############################# Server Basics #############################
  
  # The id of the broker. This must be set to a unique integer for each broker.
  broker.id=0
  
  # Switch to enable topic deletion or not, default value is false
  delete.topic.enable=true
  
  ############################# Socket Server Settings ##########################$
  
  # The address the socket server listens on. It will get the value returned from
  # java.net.InetAddress.getCanonicalHostName() if not configured.
  #   FORMAT:
  #     listeners = listener_name://host_name:port
  #   EXAMPLE:
  #     listeners = PLAINTEXT://your.host.name:9092
  #listeners=PLAINTEXT://9092
  
  # Hostname and port the broker will advertise to producers and consumers. If no$
  # it uses the value for "listeners" if configured.  Otherwise, it will use the $
  # returned from java.net.InetAddress.getCanonicalHostName().
  advertised.listeners=PLAINTEXT://hidden_ip:55091
  </code></pre>
  
  <p>I edited advertised.listeners because there is a proxy to redirect requests to the broker. Anyway until some weeks ago everything worked fine...</p>
  
  <p>My step to start kafka:</p>
  
  <pre><code>1- service zookeeper start 
  2- ./kafka_2.11-0.11.0.0/bin/kafka-server-start.sh ~/kafka_2.11-0.11.0.0/config/server.properties
  </code></pre>
  
  <p>Any advises?
  Thank you</p>