I have a CentOS 6.4 machine which is set up with pam_ldap and pam_krb5. It is configured to use our Active Directory servers for authentication. I can SSH into the machine using AD accounts.
I have not set up any kind of keytab file.
I set up a crontab for an AD user on the CentOS machine, which writes some data into a file every minute. The folder the job is writing into is on an NFS share, and the folder is locked do so that only members of a specific AD group can access it. The AD user in question is a member of the group, and has no local account on the CentOS machine.
How is cron continuing to have access to run the job as the AD user when the AD user is not logged on?