Network Deployment (Distributed operating systems), v8.0 > Reference > Administrator best practices
Use the ktab command to manage the Kerberos keytab file
The Kerberos key table manager command (Ktab) allows the product administrator to manage the Kerberos service principal names and keys stored in a local Kerberos keytab file. With the IBM Software Development Kit (SDK) or Sun Java Development Kit (JDK) 1.6 or later, you can use the ktab command to merge two Kerberos keytab files.
(Solaris) To merge the ktab files, install Java Development Kit (JDK) v1.6 SR3 cumulative fix, which upgrades the JDK to v1.6.0_07.
To merge the ktab
files, install SDK v1.6
SR3 cumulative fix, which upgrades the JDK to v1.6.0.02.
(AIX) (Windows) 
To merge the ktab files, install Java Development Kit (JDK) v1.6 SR3 cumulative fix, which upgrades
the SDK to v1.6.0 Java Technology Edition SR3.
Kerberos service principal (SPN) name and keys listed in the Kerberos keytab file allow services running on the host to validate the incoming Kerberos or SPNEGO token request. Before configuring Kerberos or SPNEGO web authentication, the WAS administrator must setup a Kerberos keytab file on the host that is running WAS.
Deprecated feature:
In WAS Version 6.1, a trust association interceptor (TAI) that uses the Simple and Protected GSS-API Negotiation Mechanism (SPNEGO) to securely negotiate and authenticate HTTP requests for secured resources was introduced. In WAS v7.0, this function is now deprecated.
SPNEGO web authentication has taken its place to provide the following enhancements:
- Configure and enable SPNEGO Web Authentication and filters on the WAS side by using the admin console.
- Provide dynamic reload of SPNEGO without having to stop and restart the WAS.
- Provide fallback to an application login method if the SPNEGO
web authentication fails.
depfeat
- It is important to protect the keytab files and make them readable only by authorized product users.
- Any updates to the Kerberos keytab file using Ktab do not affect
the Kerberos database. If you change the keys in the Kerberos keytab
file, also make the corresponding changes to the Kerberos
database.
The syntax of Ktab is illustrated below by using Ktab with the -help operand.
$ ktab -help Usage: java com.ibm.security.krb5.internal.tools.Ktab [options] Available options: -l list the keytab name and entries -a <principal_name> [password] add an entry to the keytab -d <principal_name> delete an entry from the keytab -k <keytab_name> specify keytab name and path with FILE: prefix -m <source_keytab_name> <destination_keytab_name> specify merging source keytab file name and destination keytab file name
Below is an example of how Ktab is used to merge the krb5Host1.keytab file to the krb5.keytab file:
[root@wssecjibe bin]# ./ktab -m /etc/krb5Host1.keytab /etc/krb5.keytab Merging keytab files: source=krb5Host1.keytab destination=krb5.keytab Done! [root@wssecjibe bin]# ls /etc/krb5.* /etc/krb5Host1.keytab/etc/krb5.keytab /etc/krb5.keytab
Below is an example of how Ktab is used on a LINUX platform to add new principal names to the Kerberos keytab file, where ot56prod is the password for the Kerberos principal name:
[root@wssecjibe bin]# ./ktab -a HTTP/wssecjibe.austin.ibm.com@WSSEC.AUSTIN.IBM.COM ot56prod -k /etc/krb5.keytab Done! Service key for principal HTTP/wssecjibe.austin.ibm.com@WSSEC.AUSTIN.IBM.COM saved
Below is an example of how Ktab is used on a Linux platform to list Kerberos keytab file content.
[root@wssecjibe bin]# ./ktab
KVNO Principal
---- ---------
1 HTTP/wssecjibe.austin.ibm.com@WSSEC.AUSTIN.IBM.COM
[root@wssecjibe bin]# ls /etc/krb5.*
/etc/krb5.conf
/etc/krb5.keytab
Tip: We can run the ktab
command from the install_root/java/jre/bin directory.
Single sign-on for HTTP requests using SPNEGO TAI (deprecated)
Kerberos (KRB5) authentication mechanism support for security
Create a Kerberos service principal and keytab file used by the WAS SPNEGO TAI (deprecated)
Related
Single sign-on capability with SPNEGO TAI - checklist (deprecated)
Kerberos: The Network Authentication Protocol