Network Deployment (Distributed operating systems), v8.0 > Secure applications and their environment > Authenticate users > Select an authentication mechanism > Set up Kerberos as the authentication mechanism for WAS > 3. Configure Kerberos as the authentication mechanism for WebSphere Application Sever

Configure Kerberos as the authentication mechanism using the administrative console

We can use the administrative console to configure Kerberos as the authentication mechanism for the application server. When you have entered and applied the required information to the configuration, the Kerberos service principal name is formed as <service name>/ <fully qualified hostname>@KerberosRealm, and is used to verify incoming Kerberos token requests.

Read about Kerberos (KRB5) authentication mechanism support for security to understand the Kerberos authentication mechanism in this version of WAS. We must have completed the following steps before you configure Kerberos as the authentication mechanism :

• If you do not already have a Kerberos configuration file, krb5.ini or krb5.conf, use the createkrbConfigFile command task to create the Kerberos configuration file. Read about Create a Kerberos configuration file for more information.
• We must have a Kerberos keytab file, krb5.keytab, that contains a Kerberos service principal name (SPN), <service_name>/ <fully_qualified hostname>@KerberosRealm, for each machine that run WebSphere application servers. The service name can be anything you choose; the default value is WAS.

  For example, if we have two application server machines, host1.austin.ibm.com and host2.austin.ibm.com, the Kerberos keytab file must contain the <service_name>/host1.austin.ibm.com and <service_name>/host2.austin.ibm.com SPNs and their Kerberos keys.

  Kerberos will only load and use one keytab file per session. For example, if Kerberos is configured, and to use a new keytab file with the same name and location as the previous keytab file, first restart the server to use the new keytab file.

  If you are configuring Kerberos for the first time, and you accidentally use the wrong keytab file, unconfigure Kerberos and restart the server before you can configure Kerberos again using a new keytab file. This is not true, however, if we have the Java SE Development Kit (JDK) with SP3 installed.

We must first enable global and application security.

If Kerberos is configured in global security, but to configure Simple and Protected GSS-API Negotiation (SPNEGO) on a domain using a different Kerberos realm, first use the Java ktab -m command to merge existing keytab files into one keytab file. Use that merged keytab file to configure Kerberos and SPNEGO on global and domain security.

Procedure

1. In the administrative console, click Security > Global security.

2. From Authentication, click Kerberos configuration.

3. Enter your Kerberos service name. By convention, a Kerberos service principal is divided into three parts: the primary, the instance, and the Kerberos realm name. The format of the Kerberos service principal name is <service_Name>/ <fully_qualified hostName>@KERBEROS_REALM. The service name is the first part of the Kerberos service principal name. For example, in WAS/test.austin.ibm.com@AUSTIN.IBM.COM, the service name is WAS. In this example, the keytab file must have the Kerberos service principal name,WAS/test.austin.ibm.com@AUSTIN.IBM.COM, and its keys.

   If you receive an error message when enabling Kerberos, it is possible that the fully qualified hostname might need to be manually changed to the long name, not the short name.

4. Enter the Kerberos configuration file name or click Browse to locate it. The Kerberos client configuration file, krb5.conf or krb5.ini, contains Kerberos configuration information, including the locations of the Key Distribution Centers (KDCs) for the realm of interest. The krb5.conf file is the default file name for all platforms except the Windows operating system, which uses the krb5.ini file.

   The Kerberos configuration file name and Kerberos keytab file name path do not have to be absolute paths. We can use WebSphere variables for the paths instead. If we have a mixed platform environment, you can use the ${CONF_OR_INI} variable for the Kerberos configuration file. Security configuration will expand it to ini for Windows or conf for non-Windows platforms For example:

   ${WAS_INSTALL_ROOT}\etc\krb5\krb5.${CFG_OR_INI}
   

5. Optional: Enter the Kerberos keytab file name or click Browse to locate it. The Kerberos keytab file contains one or more Kerberos service principal names and keys. The default keytab file is krb5.keytab. It is important for hosts to protect their Kerberos keytab files by storing them on the local disk, which makes them readable only by authorized users. Read about Create a Kerberos service principal name and keytab file for more information. If not specified, the default keytab in the Kerberos configuration file is used.

   The Kerberos configuration file name and Kerberos keytab file name path do not have to be absolute paths. We can use WebSphere variables for the paths instead.

   ${WAS_INSTALL_ROOT}\etc\krb5\krb5.keytab
   

6. Enter the name of your Kerberos realm in the Kerberos realm name field. In most cases, your realm is your domain name in uppercase letters. If not specified, the default Kerberos realm name in the Kerberos configuration file is used.

   For example, a machine with the domain name of test.austin.ibm.com has a Kerberos realm name of AUSTIN.IBM.COM.

   The Kerberos realm name for the KDC for Microsoft is an uppercase value of the Domain Controller name.

7. Optional: Trim Kerberos realm from principal name is selected by default. We can clear this option if you want the suffix of the Kerberos principal name to be retained. This option specifies whether the Kerberos login module removes the suffix of the principal user name, starting from the @ that precedes the Kerberos realm name. If this attribute is set to true, the suffix of the principal user name is removed. If this attribute is set to false, the suffix of the principal name is retained. The default value used is true.

   The built-in mapping module uses the full Kerberos principal name and Kerberos realm for the mapping, regardless of what the Trim Kerberos realm from principal name field is set to.

8. Optional: Enable delegation of Kerberos credentials is selected by default. This option specifies whether the Kerberos delegated credentials are extracted from the client request. The Kerberos authentication token (KRBAuthnToken) is created with the client principal name and the client delegate Kerberos ticket if the client is sent the Kerberos delegation credential as part of the request. The KRBAuthnToken is stored in the client subject. The KRBAuthnToken is propagated to the downstream server as part of the security attribute propagation. If a customer application needs the GSSCredential for authentication with a backend resource or a downstream server, retrieve the GSSCredential from the KRBAuthnToken using the com.ibm.wsspi.wssecurity.platform.token.KRBAuthnToken.getGSSCredential() method and place it in the subject.

   If you don't check this option, the KRBAuthnToken only has the Kerberos principal name.

   If this parameter is true, and the runtime environment cannot extract a client GSS delegation credential, then a warning message is displayed.

9. Optional: Under Mapping Kerberos principal names to SAF identities, select the Use the KERB segment of a SAF user profiler radio button to o use the built-in mapping module to map a Kerberos principal name to System Authorization Facility (SAF) identity on z/OS. This mapping only takes place when the active user registry is Local OS.

   The built-in mapping module uses the full Kerberos principal name and Kerberos realm for the mapping, regardless of what the Trim Kerberos realm from principal name field is set to.

   There is some additional setup required. Read for more information.

10. Click OK.

11. Optional: Configure SAF to not use the APPL class for restricting access to applications running on WAS. The default value is enabled. You might want to disable checking the SAF APPL class if this class was previously inactive on your z/OS security server, but will then be activated after configuring the z/OS KDC.

    To disable it in the administrative console:

    1. Click Security > Global Security > External authorization providers.
    2. Ensure that System Authorization Facility (SAF) authorization is selected from the drop-down menu.

    3. Click Configure.
    4. Deselect Use APPL profile to restrict access to WAS.

    For more information on this setting, read about the z/OS System Authorization Facility authorization.

Results

When you select Apply or OK the Kerberos authentication is automatically tested. If the Kerberos configuration is not complete, a message is displayed that indicates authentication failure.

You have now configured and saved Kerberos as the authentication mechanism for WAS.

What to do next

To enable SPNEGO, click SPNEGO web authentication enablement from Related Configuration.

SPNEGO web authentication and Kerberos authentication use the same Kerberos client configuration and keytab files.

When you attempt to authenticate to the administrative console, use an administrative user ID that exists in the KDC that is associated with the application server. If you use an administrative user ID exists in a different KDC that is not associated with the administrative console, the login process fails and following error message is added to the log file:

SECJ9200E: No Kerberos credential found in subject credential set.

For example, the client might be associated with a different KDC than the application server.

Related

Kerberos authentication settings
Create a Kerberos configuration file
Create a Kerberos service principal name and keytab file
Map of a client Kerberos principal name to the WebSphere user registry ID
Authenticate users
Configure CSIV2 inbound and outbound communication settings

Related

Kerberos authentication commands
CSIv2 inbound communications settings
CSIv2 outbound communications settings
Use the ktab command to manage the Kerberos keytab file
Kerberos: The Network Authentication Protocol

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