title: Failed to connect to and describe Kafka cluster In Standalone mode
body: <p>I have installed zookeeper and kafka,zookeeper is ruuning fine but as per my requirement I want to run Kafka-connect standalone to connect kafka and cassandsra. I am using following command to start kafka server<code> kafka/bin/connect-standalone.sh kafka/config/connect-standalone.properties kafka-connect-cassandra-sink-1.4.0/conf/cassandra-sink-standalone.properties</code> . The connect-standalone.properties configuration file is given below:</p>
  <pre><code>bootstrap.servers=localhost:9092
  
  key.converter=org.apache.kafka.connect.storage.StringConverter
  value.converter=org.apache.kafka.connect.json.JsonConverter
  value.converter.schemas.enable=true
  
  offset.storage.file.filename=/tmp/connect.offsets
  offset.flush.interval.ms=10000
  
  plugin.path=/home/shamama/kafka-connect-cassandra-sink-1.4.0/kafka-connect-cassandra-sink-1.4.0.jar
  
  ############################# Zookeeper #############################
  
  # Zookeeper connection string (see zookeeper docs for details).
  # This is a comma separated host:port pairs, each corresponding to a zk
  # server. e.g. &quot;127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002&quot;.
  # You can also append an optional chroot string to the urls to specify the
  # root directory for all kafka znodes.
  zookeeper.connect=localhost:2181
  
  # Timeout in ms for connecting to zookeeper
  zookeeper.connection.timeout.ms=18000
  
  
  listeners=PLAINTEXT://localhost:9092
  #advertised.listeners=PLAINTEXT://localhost:9092
  </code></pre>
  <p>The following error is occurring after starting kafka standalone server:</p>
  <pre><code>org.apache.kafka.connect.errors.ConnectException: Failed to connect to and describe Kafka cluster. Check worker's broker connection and security properties.
      at org.apache.kafka.connect.util.ConnectUtils.lookupKafkaClusterId(ConnectUtils.java:70)
      at org.apache.kafka.connect.util.ConnectUtils.lookupKafkaClusterId(ConnectUtils.java:51)
      at org.apache.kafka.connect.cli.ConnectStandalone.main(ConnectStandalone.java:82)
  Caused by: java.util.concurrent.ExecutionException: org.apache.kafka.common.errors.TimeoutException: Call(callName=listNodes, deadlineMs=1628583433705, tries=1, nextAllowedTryMs=1628583433806) timed out at 1628583433706 after 1 attempt(s)
      at org.apache.kafka.common.internals.KafkaFutureImpl.wrapAndThrow(KafkaFutureImpl.java:45)
      at org.apache.kafka.common.internals.KafkaFutureImpl.access$000(KafkaFutureImpl.java:32)
      at org.apache.kafka.common.internals.KafkaFutureImpl$SingleWaiter.await(KafkaFutureImpl.java:89)
      at org.apache.kafka.common.internals.KafkaFutureImpl.get(KafkaFutureImpl.java:260)
      at org.apache.kafka.connect.util.ConnectUtils.lookupKafkaClusterId(ConnectUtils.java:64)
  </code></pre>
  <p>I cannot figure out my mistake.Please help.</p>