Port numbers

In Hadoop 3.x, many of the ports for various services have been changed.

Previously, the default ports of multiple Hadoop services were in the Linux ephemeral port range (32768–61000). This indicated that at startup, services would sometimes fail to bind to the port with another application due to a conflict.

These conflicting ports have been moved out of the ephemeral range, affecting the NameNode, Secondary NameNode, DataNode, and KMS. 

The changes are listed as follows:

• NameNode ports: 50470 → 9871, 50070 → 9870, and 8020 → 9820
• Secondary NameNode ports: 50091 → 9869 and 50090 → 9868
• DataNode ports: 50020 → 9867, 50010 → 9866, 50475 → 9865, and 50075 → 9864