Step 3: Modify the httpfs-site.xml File

A Kerberos-ready version of the httpfs-site.xml file called httpfs-site.xml.kerberos is provided in /opt/mapr/httpfs/httpfs-1.0/etc/hadoop. Edit this file and specify the Kerberos principal name for the nodes running HttpFS, restart the HttpFS server, and then test the set-up. Each step is explained here.

To set up the httpfs-site.xmlfile for each node running the HttpFS service, follow these steps:

Assign a new name to the existing httpfs-site.xml file (to preserve the original version when the file gets overwritten in step 2).
```
cp /opt/mapr/httpfs/httpfs-1.0/etc/hadoop httpfs-site.xml httpfs-site.xml.original
```
Copy the kerberos version (httpfs-site.xml.kerberos) to the existing httpfs-site.xml file.
```
cp /opt/mapr/httpfs/httpfs-1.0/etc/hadoop httpfs-site.xml.kerberos httpfs-site.xml
```
Edit the httpfs-site.xml file and insert the principal name as shown, substituting your fully qualified domain name and realm for perfnode153.perf.lab@mapr.com.
```
<property>
  <name>
    httpfs.authentication.kerberos.principal
  </name>
  <value>
    HTTP/perfnode153.perf.lab@mapr.com
  </value>
</property>
```

Restart the HttpFS server so the changes will take effect.

maprcli node services -name httpfs -action restart -nodes <node_name>

Test that security is in place by entering the following command to create a file in the filesystem. The command will fail if security is not set up correctly.
```
curl --negotiate -u : -b ~/cookiejar.txt -c ~/cookiejar.txt -i -X PUT
"http://perfnode153.perf.lab:14000/webhdfs/v1/user/mapr/some_file?op=MKDIRS"
```