[Samba] Printing via SMB-Kerberos no longer works

Robert Schetterer rs at sys4.de
Sat Sep 22 11:30:08 UTC 2018

Am 22.09.2018 um 13:24 schrieb Alex Persson:
>> Sent: Saturday, September 22, 2018 at 12:08 PM
>> From: "Robert Schetterer via samba" <samba at lists.samba.org>
>> To: samba at lists.samba.org
>> Subject: Re: [Samba] Printing via SMB-Kerberos no longer works
>> Am 22.09.2018 um 09:49 schrieb Alex Persson via samba:
>>> After upgrading from Ubuntu 16.04 to 18.04 printing via SMB-Kerberos no longer works (printing still works in 18.04 when I print via SMB but I don't want to have the password stored in clear text in /usr/lib/cups/backend/smb).
>>> In 16.04 I can just type "lpr file.pdf", but when doing this in 18.04 I get "Password for [myuser] on localhost?" and it expects me to type my password instead of using my Kerberos ticket for sending the print job to the print queue.
>>> I have the same Kerberos ticket available according to "klist" in 18.04 as I had in 16.04.
>>> I have "AuthInfoRequired negotiate" in /etc/cups/printers.conf
>>> The file /usr/lib/cups/backend/smb is a symbolic link pointing to /usr/lib/x86_64-linux-gnu/samba/smbspool_krb5_wrapper (in 16.04 it was pointing at /usr/bin/smbspool_krb5_wrapper).
>>> The permission is 700 on /usr/lib/x86_64-linux-gnu/samba/smbspool_krb5_wrapper.
>>> The version of cups is 2.2.7-1ubuntu2.1 in 18.04 while it was 2.1.3-4ubuntu0.5 in 16.04.
>>> The version of smbclient is 2:4.7.6+dfsg~ubuntu-0ubuntu2.2 in 18.04 while it was 2:4.3.11+dfsg-0ubuntu0.16.04.16 16.04.
>>> Can you please help me figure out what the problem is? Maybe it is something wrong with smbspool_krb5_wrapper from the smbclient package?
>> this feature broke times before by varia reasons
>> "just a shot in the dark", if you use kerberos tickets in /tmp then
>> stuff changed in 18.04 this also broke our cifs automounter
>> see here
>> https://blog.nutmeg.at/2017/04/17/getting-pam-krb5-working-autofs-and-cifs/
>> i did
>> default_ccache_name = FILE:/tmp/krb5cc_%{uid}
>> in /etc/krb5.conf
>> to fix our problem
> Thanks you very much for your answer!
> I tried to set default_ccache_name in /etc/krb5.conf as you suggest above but "lpr" still asks "Password for [myuser] on localhost?".
> My CIFS mount works fine (as before) and I have $KRB5CCNAME set in my env and it points to the ticket under /tmp/:
> $ env|grep KRB
> KRB5CCNAME=FILE:/tmp/krb5cc_5241_RIBf32
> I wonder what makes "lpr" ask me "Password for [myuser] on localhost?" instead of using my Kerberos ticket as it does in Ubuntu 16.04? I see that /usr/bin/lpr comes with the package cups-bsd version 2.2.7-1ubuntu2.1 in Ubuntu 18.04 while it is 2.1.3-4ubuntu0.5 in Ubuntu 16.04.
> Best regards, Alex

our stuff may not comparable to your setup, our ksmb print module is a
modified version, but i am nearly sure changes in new kerberos version
at 18.04 are your problem. I think you should log very verbose to find
the exact problem

Best Regards
MfG Robert Schetterer

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