[Samba] [Solved] A working CUPS authentication now fails without change anything...

Andrey Repin anrdaemon at yandex.ru
Tue May 12 13:28:51 MDT 2015

Greetings, Daniel Carrasco Marín!

>>>  Hi again!!, this time is not for help request as always :P finally i've
>>>> found the solution and I want to share it.
>>>> The problem was just permissions. If you change the keytab permission to
>>>> 644 it works perfect: chmod 644 /etc/krb5.keytab
>>>> Anyway I don't understand why the daemons can't read that file when are
>>>> running as root.
>>> Not all daemons are run as root, far from that.
>>> Most of single-purpose daemons, such as cups, run as their own users.
>> Yep, this is done for security purposes so that if one process is
>> compromised, it doesn't have administrative access to the rest of the
>> system.
>> In a similar vein, you don't generally want any process on the machine to
>> have access to some things.  The system kerberos keytab is probably one of
>> those.  If cups is running as it's own user, a better solution would be to
>> either generate a new keytab just for cups, or copy the existing keytab and
>> make it only readable by the cups user.
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> Yes, for now keytab is compromised.

> Cups calls pam authentication, and pam use winbind then I need to give
> permissions to winbind daemon but i don't know what account is using that
> daemon. How i can see it?, because ps aux shows the most as root.

winbind normally have access to Kerberos keytab by default.
I see no reason why it would not.

With best regards,
Andrey Repin
Tuesday, May 12, 2015 22:28:05

Sorry for my terrible english...

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