kerberos default_ccache_name with sssd

Thu Jun 13 12:26:48 AEST 2024

Thank you for the tip!

I gave it a try and it works!
I commented out krb5_ccachedir and krb5_ccname_template from sssd.conf.
Updated default_ccache_name in krb5.conf to use KCM:
Enabled the sssd-kcm service
Restarted sssd service and voila!

rocky8client.domain.net
Ticket cache: KCM:2000:16626
Default principal: jdoe at DOMAIN.NET

Valid starting Expires Service principal
06/12/2024 22:06:43 06/13/2024 22:06:43 krbtgt/DOMAIN.NET at DOMAIN.NET
 renew until 06/12/2024 22:06:43

rocky9client.domain.net
Ticket cache: KCM:2000:38480
Default principal: jdoe at DOMAIN.NET

Valid starting Expires Service principal
06/12/24 22:06:43 06/13/24 22:06:43 krbtgt/DOMAIN.NET at DOMAIN.NET
 renew until 06/12/24 22:06:43
Your password will expire in 23 hours.

rocky9server.domain.net
Ticket cache: KCM:2000:82289
Default principal: jdoe at DOMAIN.NET

Valid starting Expires Service principal
06/13/24 02:06:44 06/14/24 02:06:44 krbtgt/DOMAIN.NET at DOMAIN.NET
 renew until 06/13/24 02:06:44

rocky8server.domain.net
Ticket cache: KCM:2000:29965
Default principal: jdoe at DOMAIN.NET

Valid starting Expires Service principal
06/13/24 02:06:45 06/14/24 02:06:45 krbtgt/DOMAIN.NET at DOMAIN.NET
 renew until 06/13/24 02:06:45

All vms rocky8/9 save the cache in memory. And the nice thing is with sssd-kcm is that it survives a reboot, so thats cool.

Thank you for the support!

Best,
Dave
On Jun 12, 2024 at 8:31 PM -0400, Douglas E Engert <deengert at gmail.com>, wrote:
> I have not looked at Kerberos is years. But it looks like KRB5CCNAME comes from:
> https://github.com/openssh/openssh-portable/blob/master/gss-serv-krb5.c#L134-L197
> But it depends on which version of Kerberos you have, and if you are also use PAM.
>
> Google for: heimdal kerberos cache name
> It looks like there is now a SSSD Kerberos Cache Manager rather then storing in individual file.
>
> On 6/11/2024 7:21 PM, Dave Macias wrote:
> > Just to show what i mean when i ssh into my vms, 2 vms save the cache in /tmp and the other 2 in /home. See what happens when i run the loop below:
> >
> > > for i in rocky8client rocky9client rocky9server rocky8server; do /usr/bin/sshpass -p password /usr/bin/ssh -l jdoe $i "hostname; klist"; done
> >
> > rocky8client.domain.net <http://rocky8client.domain.net>
> > Ticket cache: FILE:/tmp/krb5cc_2000_WP04h8h0sa
> > Default principal: jdoe at DOMAIN.NET <https://mailto:jdoe@DOMAIN.NET>
> >
> > Valid starting Expires Service principal
> > 06/11/2024 17:58:09 06/12/2024 17:58:09 krbtgt/DOMAIN.NET at DOMAIN.NET <https://mailto:krbtgt/DOMAIN.NET@DOMAIN.NET>
> >  renew until 06/11/2024 17:58:09
> >
> > rocky9client.domain.net <http://rocky9client.domain.net>
> > Ticket cache: FILE:/tmp/krb5cc_2000_XXXXkYi1X5
> > Default principal: jdoe at DOMAIN.NET <https://mailto:jdoe@DOMAIN.NET>
> >
> > Valid starting Expires Service principal
> > 06/11/24 17:58:10 06/12/24 17:58:10 krbtgt/DOMAIN.NET at DOMAIN.NET <https://mailto:krbtgt/DOMAIN.NET@DOMAIN.NET>
> >  renew until 06/11/24 17:58:10
> > Your password will expire in 23 hours.
> >
> > rocky9server.domain.net <http://rocker9server.domain.net>
> > Ticket cache: FILE:/home/jdoe/.krb5cc_2000
> > Default principal: jdoe at DOMAIN.NET <https://mailto:jdoe@DOMAIN.NET>
> >
> > Valid starting Expires Service principal
> > 06/11/24 21:58:11 06/12/24 21:58:11 krbtgt/DOMAIN.NET at DOMAIN.NET <https://mailto:krbtgt/DOMAIN.NET@DOMAIN.NET>
> >  renew until 06/11/24 21:58:11
> >
> > rocky8server.domain.net <http://rocker8server.domain.net>
> > Ticket cache: FILE:/home/jdoe/.krb5cc_2000
> > Default principal: jdoe at DOMAIN.NET <https://mailto:jdoe@DOMAIN.NET>
> >
> > Valid starting Expires Service principal
> > 06/11/24 21:58:12 06/12/24 21:58:12 krbtgt/DOMAIN.NET at DOMAIN.NET <https://mailto:krbtgt/DOMAIN.NET@DOMAIN.NET>
> >  renew until 06/11/24 21:58:12
> > On Jun 11, 2024 at 5:05 PM -0400, Dave Macias <davama at gmail.com>, wrote:
> > > Thank you both for the replies and explanation!
> > >
> > > @douglas
> > >
> > > Can i set KRB5CCNAME somewhere so that it uses /home? Where?
> > >
> > > But even if i could set the env variable i have this odd behavior:
> > >
> > > I now have 4 vms running.
> > > 2 are rocky8 and 2 are rocky9, with same settings and versions I stated on my first post.
> > >
> > > From the 4 vms, when I ssh into them, 2 of them set a cache file in the users home and the other two save it in /tmp.
> > > I cant seem to understand why my other two vms do not want to setup the cache in the /home.
> > >
> > > The only difference i can think of is that the two vms that do use /home, are the actual kdc/ldap servers. The two “bad” vms are clients, only running sssd/sshd.
> > >
> > > Upon ssh login to each of the 4 vms, a KRB5CCNAME=FILE:/bla environment variable is set; which will be /tmp or /home, depending on the vm.
> > >
> > > Someone requested a trace, so ill post that tomorrow, hopefully it will be helpful.
> > >
> > > Appreciate very much you all’s input!
> > >
> > > Best,
> > > Dave
> > > On Jun 11, 2024 at 2:00 PM -0400, Douglas E Engert <deengert at gmail.com>, wrote:
> > > >
> > > >
> > > > On 6/6/2024 8:26 AM, Dave Macias wrote:
> > > > > *I wanted to see if I could make the cache file user-specific, instead of
> > > > > the default location (/tmp/krb5cc-blabla).*
> > > > SSH is creating a separate ticket cache file for each login session and owned by the user.
> > > > This has been the preferred way to do this for decades.
> > > > https://kerberos.mit.narkive.com/YJB4Hshz/krb5ccname-and-sshd
> > > >
> > > > Your: "Ticket cache: FILE:/tmp/krb5cc_2000_tgiettMBSK" looks like it is set by sshd and your environment should have a KRB5CCNAME with that name.
> > > > If you share the ticket cache between multiple login sessions, when the first session ends,
> > > > the "GSSAPICleanupCredentials yes" will cause the shared ticket cache to be deleted. Using /tmp means the cache is destroyed upon a shutdown/restart. /tmp is also a local file system. /home may be on
> > > > a network disk which has other issues.
> > > > > openssh-unix-dev mailing list
> > > > > openssh-unix-dev at mindrot.org
> > > > > https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
> > > >
> > > > --
> > > >
> > > > Douglas E. Engert <DEEngert at gmail.com>
> > > >
> > > >
> > > > _______________________________________________
> > > > openssh-unix-dev mailing list
> > > > openssh-unix-dev at mindrot.org
> > > > https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
>
> --
>
> Douglas E. Engert <DEEngert at gmail.com>
>
>