question Setting the NameNode port (8020) to listen outside of localhost in Archives of Support Questions (Read Only)

Setting the NameNode port (8020) to listen outside of localhost

JakeZ — Fri, 16 Sep 2022 08:49:03 GMT

I have manually installed CDH4 on a machine according to the default configurations given in the Cloudera installation documentation.

http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/4.2.1/CDH4-Installation-Guide/CDH4-Installation-Guide.html

I configured the machine to run in pseudo-distributed mode and the pseudo-cluster is working as expected when using the HDFS and MapReduce programs on the machine itself.

However, I have an application that is need of access to the NameNode port (8020). I am unable to make a connection to this port from an external machine despite having this port opened on the firewall. I found that the NameNode service is only listening on the localhost, thus rejecting requests from outside machines to communicate on this port.

$ sudo netstat -tulpn | grep :8020

tcp        0      0 127.0.0.1:8020              0.0.0.0:*                   LISTEN      16504/java

I want this service to listen to requests outside of the machine itself, just like I can communicate through port 50030 or 50070 on another machine. I have configured vi /etc/hadoop/conf.pseudo.mr1/core-site.xml to reference the machine name (hadoop) rather than localhost:

<property>
  <name>fs.default.name</name>
  <value>hdfs://hadoop:8020</value>
</property>

After restarting the NameNode service, I find that it is still only listening of 127.0.0.1. Is there any way to open to this port up for external usage?

Re: Setting the NameNode port (8020) to listen outside of localhost

JakeZ — Wed, 16 Oct 2013 19:03:54 GMT

I found the solution. I had neglected to find the article detailing network configuration which specified that the /etc/hosts file should have the fully-qualified domain name listed, not just the machine name.

http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/4.2.1/CDH4-Installation-Guide/cdh4ig_topic_4_4.html

Re: Setting the NameNode port (8020) to listen outside of localhost

Clint — Wed, 16 Oct 2013 19:34:05 GMT

Thanks for closing the loop with us and posting back the solution, JakeZ

Re: Setting the NameNode port (8020) to listen outside of localhost

Ciccio — Fri, 24 Oct 2014 12:08:33 GMT

The solution is much Simpler

In the HDFS configuration in cloudera there is a property called

Bind NameNode to Wildcard Address. You just need to check the box and it will bind the service on 0.0.0.0

then restart hdfs service

[cloudera@localhost ~]$ sudo netstat -tulpn | grep :8020
tcp 0 0 0.0.0.0:8020 0.0.0.0:* LISTEN 29966/java

Re: Setting the NameNode port (8020) to listen outside of localhost

ThanhP — Mon, 30 Sep 2019 12:13:44 GMT

Please guide how to follow step by step. thank you very much!