ktab allows the user to manage the principal names and service keys stored in a local key table. Principal and key pairs listed in the keytab allow services running on a host to authenticate themselves to the Key Distribution Center (KDC). Before a server can be setup to use Kerberos, the user must setup a keytab on the host running the server. Note that any updates made to the keytab using ktab do not affect the Kerberos database. If you change the keys in the keytab, you must also make the corresponding changes to the Kerberos database.
A keytab is a hosts copy of its own keylist, which is analogous to a users password. An application server that needs to authenticate itself to the Key Distribution Center (KDC) must have a keytab which contains its own principal and key. Just as it is important for users to protect their passwords, it is equally important for hosts to protect their keytabs. You should always store keytab files on the local disk and make them readable only by root. You should never send a keytab file over a network in the clear.
ktab -l [-k <keytab_name>]
ktab [-a <principal_name> <password>] [-k <keytab_name>]
ktab [-d <principal_name>] [-k <keytab_name>]
|-l||List the keytab name and entries.|
|-a||<principal_name> <password> Add an entry to the keytab. No changes are made to the Kerberos database. (DO NOT SPECIFY YOUR PASSWORD ON COMMAND LINE OR IN A SCRIPT.)|
|-d||<principal_name> Delete an entry from the keytab. No changes are made to the Kerberos database.|
|-k||<keytab_name> Specify keytab name and path with prefix FILE:|
To add a new principal to the key table (note that you will be prompted for your password):
ktab -a email@example.com
To delete a principal from the key table:
ktab -d firstname.lastname@example.org