Configuring Kerberos for Linux Clients

Configuring Kerberos for Linux Clients

You can configure Linux client applications to connect to a Greenplum Database system that is configured to authenticate with Kerberos.

If your JDBC application on RedHat Enterprise Linux uses Kerberos authentication when it connects to your Greenplum Database, your client system must be configured to use Kerberos authentication. If you are not using Kerberos authentication to connect to a Greenplum Database, Kerberos is not needed on your client system.

For information about enabling Kerberos authentication with Greenplum Database, see the chapter "Setting Up Kerberos Authentication" in the Greenplum Database Administrator Guide.

Requirements

The following are requirements to connect to a Greenplum Database that is enabled with Kerberos authentication from a client system with a JDBC application.

Prerequisites

  • Kerberos must be installed and configured on the Greenplum Database master host.
    Important: Greenplum Database must be configured so that a remote user can connect to Greenplum Database with Kerberos authentication. Authorization to access Greenplum Database is controlled by the pg_hba.conf file. For details, see "Editing the pg_hba.conf File" in the Greenplum Database Administration Guide, and also see the Greenplum Database Security Configuration Guide.
  • The client system requires the Kerberos configuration file krb5.conf from the Greenplum Database master.
  • The client system requires a Kerberos keytab file that contains the authentication credentials for the Greenplum Database user that is used to log into the database.
  • The client machine must be able to connect to Greenplum Database master host.

    If necessary, add the Greenplum Database master host name and IP address to the system hosts file. On Linux systems, the hosts file is in /etc.

Required Software on the Client Machine

  • The Kerberos kinit utility is required on the client machine. The kinit utility is available when you install the Kerberos packages:
    • krb5-libs
    • krb5-workstation
    Note: When you install the Kerberos packages, you can use other Kerberos utilities such as klist to display Kerberos ticket information.
  • Java JDK

    Java JDK 1.7.0_17 is supported on Red Hat Enterprise Linux 6.x.

    Java JDK 1.6.0_21 is supported on Red Hat Enterprise Linux 5.x.

  • Ensure that JAVA_HOME is set to the installation directory of the supported Java JDK.

Setting Up Client System with Kerberos Authentication

To connect to Greenplum Database with Kerberos authentication requires a Kerberos ticket. On client systems, tickets are generated from Kerberos keytab files with the kinit utility and are stored in a cache file.

  1. Install a copy of the Kerberos configuration file krb5.conf from the Greenplum Database master. The file is used by the Greenplum Database client software and the Kerberos utilities.

    Install krb5.conf in the directory /etc.

    If needed, add the parameter default_ccache_name to the [libdefaults] section of the krb5.ini file and specify location of the Kerberos ticket cache file on the client system.

  2. Obtain a Kerberos keytab file that contains the authentication credentials for the Greenplum Database user.
  3. Run kinit specifying the keytab file to create a ticket on the client machine. For this example, the keytab file gpdb-kerberos.keytab is in the the current directory. The ticket cache file is in the gpadmin user home directory.
    > kinit -k -t gpdb-kerberos.keytab -c /home/gpadmin/cache.txt 
       gpadmin/kerberos-gpdb@KRB.EXAMPLE.COM

Running a Java Application

Accessing Greenplum Database from a Java application with Kerberos authentication uses the Java Authentication and Authorization Service (JAAS)

  1. Create the file .java.login.config in the user home folder.

    For example, on a Linux system, the home folder is similar to /home/gpadmin.

    Add the following text to the file:

    pgjdbc {
      com.sun.security.auth.module.Krb5LoginModule required
      doNotPrompt=true
      useTicketCache=true
      ticketCache = "/home/gpadmin/cache.txt"
      debug=true
      client=true;
    };
  2. Create a Java application that connects to Greenplum Database using Kerberos authentication and run the application as the user.

This example database connection URL uses a PostgreSQL JDBC driver and specifies parameters for Kerberos authentication.

jdbc:postgresql://kerberos-gpdb:5432/mytest? 
  kerberosServerName=postgres&jaasApplicationName=pgjdbc& 
  user=gpadmin/kerberos-gpdb

The parameter names and values specified depend on how the Java application performs Kerberos authentication.