krb5 query realms ATHENA.MIT.EDU kdc krb5 query1 realms ATHENA.MIT.EDU kdc krb5 query libdefaults ticket_lifetime krb5 query1 libdefaults ticket_lifetime krb5 query libdefaults not_present krb5 query1 libdefaults not_present krb5 list_sections libdefaults krb5 list_sections realms krb5 list_relations libdefaults krb5 list_relations realms krb5 list_relations realms ATHENA.MIT.EDU