Handling of kerberos machine account password changes (eg domain rejoin)

Alexander Bokovoy ab at samba.org
Thu Nov 1 07:27:14 MDT 2012

On Thu, Nov 1, 2012 at 3:15 PM, Andrew Bartlett <abartlet at samba.org> wrote:
> On Thu, 2012-11-01 at 07:22 +0100, Andrew Tridgell wrote:
>> The branch, master has been updated
>>        via  dd60dcf test-chgdcpass: test the ldap case for server password change
>>        via  0e6c5c0 s4-ldapclient: cope with logon failure retry in LDAP
>>        via  b0cc0d5 s4-librpc: set error code to LOGON_FAILURE on RPC fault with access denied
>>        via  538dd04 samba-tool: "drs options" does not need a samdb connection
>>        via  5d6ae34 s4-librpc: try a 2nd logon for more error cases
>>        via  fce66b2 test_chgdpass: added test for kerberos retry
>>        via  d4ea637 libcli: use cli_credentials_failed_kerberos_login() to cope with server changes
>>        via  994696c auth: added cli_credentials_failed_kerberos_login()
>>       from  ffb608b util: remove accidently committed hunk
>> http://gitweb.samba.org/?p=samba.git;a=shortlog;h=master
> Alexander,
> I wanted to thank you for the chat we just had on IRC about these
> kerberos changes.  I think we have determined that it won't hit your use
> case, because we are careful to only remove a ticket once we have some
> evidence that the server it is for won't accept it.
> We do take particular care not to just blow away the ccache, because we
> might not have a password to recreate it (and it might, as in your
> application have come from an external kinit or s4u2proxy call).
> The reason for the change is to cope with the re-installation of a
> kerberos host, where the rejoin to the domain has no record of the old
> password, and so for up to 10 hours valid tickets in a ccache would be
> rejected, without any attempt to get a fresh ticket.
> That said, Kerberos can be a tricky beast, and I'm very happy to
> continue to work with you to address any further concerns you might have
> after your conference.

I'll make a deeper test with Fedora 18 and FreeIPA for this code after
LinuxCon Europe next week.

/ Alexander Bokovoy

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