[Samba] weekly samba kerberos failure

[Hong K Phooey]

We have a service on our windows system that drops files onto a samba share every 10 minutes.  This has worked fine, except after one week, the system will fail.  We usually restart samba and winbind on the linux side, and then restart the service on the windows box to resolve the issue.

This week we decieded to let it fail, and after an hour it seemed to allow connections to the samba share.  Here is the log file of the failures:

  172.19.6.60 (172.19.6.60) closed connection to service lorian
[2010/06/21 09:40:03,  1] smbd/sesssetup.c:342(reply_spnego_kerberos)
  Failed to verify incoming ticket with error NT_STATUS_LOGON_FAILURE!

This repeats every minute until 10:33 am, when the service was able to reconnect to the share.

Is there a reason why this would fail every week at the same time?  Do these settings have anything to do with the issue?  

Default: idmap cache time = 604800 (one week)
Default: machine password timeout = 604800

For the machine password timeout, is it necessary for it to update this often.  Can it be set to only attempt once per year, longer?

One other question, is it possible to see the data contained in secrets.tdb?  The modified time of this file always lets us know that the share failure is imminent.  For example, file date was 6/21/10 9:36 am, first connection after that time was 9:40 am and it failed.

Any assistance would be appreciated.


PDC: windows 2008 R2
Samba: 3.4.7 on ubuntu 10.4

Testparm:
Load smb config files from /etc/samba/smb.conf
rlimit_max: rlimit_max (1024) below minimum Windows limit (16384)
Processing section "[printers]"
Processing section "[print$]"
Loaded services file OK.
Server role: ROLE_DOMAIN_MEMBER
Press enter to see a dump of your service definitions

[global]
        workgroup = test
        realm = TEST.LOCAL
        server string = %h server (Samba, Ubuntu)
        security = ADS
        map to guest = Bad User
        obey pam restrictions = Yes
        password server = pdc21.test.local
        pam password change = Yes
        passwd program = /usr/bin/passwd %u
        passwd chat = *Enter\snew\s*\spassword:* %n\n *Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
        unix password sync = Yes
        syslog = 0
        log file = /var/log/samba/log.%m
        max log size = 1000
        domain master = No
        dns proxy = No
        usershare allow guests = Yes
        panic action = /usr/share/samba/panic-action %d
        idmap uid = 500-10000000
        idmap gid = 500-10000000
        template shell = /bin/bash
        winbind refresh tickets = Yes

[printers]
        comment = All Printers
        path = /var/spool/samba
        create mask = 0700
        printable = Yes
        browseable = No
        browsable = No

[print$]
        comment = Printer Drivers
        path = /var/lib/samba/printers