I set up a vanilla AWS EC2 instance with the HDP 3.0 Sandbox running in a Docker container. It looks like it maps 8020 from the host to the container. I set up a security group policy to open 8020 to my IP address so I could make a HDFS client connection with ListHDFS in NiFi. Got a ConnectTimeoutException saying it timed out after 1000ms. Can someone tell me if this sounds like a configuration issue with my AWS setup or with HDFS?