What ports need to be open on the hadoop/hdfs machine?
Which ports hunk uses to read the files?
Which ports the splunk indexers use to write files?
1) All the Splunk Ports (8000 - Web, 8089 - Admin, 8065 - App Server, 9997 - TCP Inputs, 8191 - KV Store)
Since Hunk is a Hadoop Client node, you will also need to consider these Hadoop ports:
2) All the Hadoop Ports - this is a long list from Cloudera =
2* ) Similar list but from Hortonworks =