On ti, 13 joulu 2016, Dan Horák wrote:
On Tue, 13 Dec 2016 12:29:57 +0200
Alexander Bokovoy <aboko...@redhat.com> wrote:

On ti, 13 joulu 2016, Daniel P. Berrange wrote:
>On Tue, Dec 13, 2016 at 12:19:45PM +0200, Alexander Bokovoy wrote:
>> On ti, 13 joulu 2016, Alexander Bokovoy wrote:
>> > On ti, 13 joulu 2016, Vít Ondruch wrote:
>> > >
>> > >
>> > > Dne 12.12.2016 v 16:02 Stephen Gallagher napsal(a):
>> > > > On 12/12/2016 04:53 AM, Vít Ondruch wrote:
>> > > > > So several questions:
>> > > > >
>> > > > > 1) When I have 2 domains I login to with kerberos, how to
>> > > > > really make it work. I don't want to kswitch all the time.
>> > > > > I am using Kerberos to authenticate my email client, so I
>> > > > > want to keep it working all the time.
>> > > > >
>> > > > There are patches still coming that will switch the fedora
>> > > > packaging tools to use GSSAPI rather than Kerberos directly,
>> > > > which will handle auto-selecting the right TGT. I'm not sure
>> > > > what the status is on this, but Patrick Uiterwijk (CCed) was
>> > > > looking into it.
>> > >
>> > > I am probably missing something, but if I am not mistaken, the
>> > > primary ticket depends on order of my kinit calls and I am
>> > > using several apps which needs kerberos authentication, so I
>> > > can hardly see how fedora packaging tools changes can solve
>> > > the major issue, i.e. if I do kinit
>> > > vondr...@fedoraproject.org, this ticket becomes the primary ...
>> > The story is always more complex than it seems.
>> >
>> > There is Kerberos protocol. There is also GSSAPI interface that
>> > allows to wrap Kerberos use under a more general security
>> > exchange means. While Kerberos tools can deal with multiple
>> > credential caches in the collection only by addressing the
>> > currently selected credentials cache, GSSAPI-aware applications
>> > enjoy ability to chose which credentials cache from the
>> > collection to use based on the realm of the target service.
>> >
>> > Koji with a patch to use python-gssapi will have ability to
>> > choose the credentials cache automatically based on the realm of
>> > the target service, regardless of what credentials cache is
>> > active right now in the collection. The version in Fedora right
>> > now (1.11.0-1.fc25) is not yet built with the patch to use
>> > python-gssapi.
>> A small correction: koji 1.11.0-1.fc25 does use
>> python-requests-kerberos which uses python-kerberos which is using
>> GSSAPI C library. I verified that koji in Fedora 25 does work with
>> credentials cache collections and properly chooses the credentials
>> cache which is not the one currently active.
>>
>> However, default Fedora 25 configuration[1] does not set the
>> default ccache name to a collection, only FreeIPA client installer
>> does this.
>>
>> As result, if you have no
>>
>> [libdefaults]
>>   default_ccache_name = KEYRING:persistent:%{uid}
>>
>> in your krb5.conf, you are using the defaults compiled into libkrb5
>> which is 'FILE:/tmp/krb5cc_%{uid}'. The latter is not a credentials
>> cache _collection_ and cannot store multiple credentials from
>> multiple realms.
>>
>> So, if you'd change default_ccache_name to a KEYRING:..-based
>> version and re-logon, you'll be able to maintain multiple
>> credentials caches at the same time.
>>
>> [1]
>> http://pkgs.fedoraproject.org/cgit/rpms/krb5.git/tree/krb5.conf?h=f25
>
>Actually that's not quite right - if you look at krb5.spec you'll
>see it then munges that krb5.conf to add
>
>   default_ccache_name = KEYRING:persistent:%{uid}
>
>so all F25 installs should get that by default - all of my fresh
>installs do.
Mea culpa. Thanks for the correction. So, for fresh F25 installs this
should be working fine -- at least with koji.

does anybody know if the krb5-auth-dialog tool [1] works with the
credentials cache?

[1] https://honk.sigxcpu.org/piki/projects/krb5-auth-dialog/
This is an incorrect question -- everything that supports Kerberos works
with the credentials caches. I guess you were asking whether
krb5-auth-dialog does use GSSAPI to choose correct credential cache out
of a _collection_? The answer is no, it does not use GSSAPI so it cannot
automatically choose the correct credential cache out of a collection.

krb5-auth-dialog directly uses krb5 API, not GSSAPI, so your only choice
with it is to use 'kswitch' utility to explicitly switch credential
cache prior to use of the krb5-auth-dialog.

--
/ Alexander Bokovoy
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