Thanks Andrew and Jeffrey.

So, from what I understand from your answers is that as long the
AFS server has a rxkad.keytab that contains the enc type the
KDC issues, things should be OK afs-wise.

To answer Andrew's questions: the test realm is a clone of our
production one, so it can issue service tickets for afs/testcell@testrealm.
With the corresponding changes to krb5.conf, CellservDB and the
like aklog will get you a session key/service ticket pair for the test
realm's "AFS service" (there are no AFS servers the client could talk
to, but that does not stop the client from getting a token). For that
sess/tkt pair I was surprised to see DES/ArcFour with old AFS client
versions and AES/AES for new client versions. Does that make sense?

The reason I am doing all this is because our batch system uses
some home made tools to decrypt the token which is used to verify
a user's identity, and I managed to port that tool to decrypt AES, but
not ArcFour. The tool basically uses the functions the AFS server code
uses I didn't get round to look into that much more, but when I saw this
thread I thought it maybe worthwhile to jump in and ask if I am trying to
achieve something that is not achievable. 

Cheers,
 Arne
________________________________________
From: [email protected] [[email protected]] on behalf 
of Andrew Deason [[email protected]]
Sent: 26 September 2013 17:52
To: [email protected]
Subject: [OpenAFS] Re: Creating service principal and keytab from active 
directory for afs/cell

On Thu, 26 Sep 2013 15:28:16 +0000
Arne Wiebalck <[email protected]> wrote:

> > For Windows 2003 I believe it should be RC4-HMAC-NT, yes. But for
> > newer versions, you need an AES (this starts with 2008 or 2008 R2).
> > But there
>
> Does that mean access to updated AFS servers would fail if AD handed out
> ArcFour encrypted service tickets for AFS?

No no, sorry, I think I was trying to simplify too much and that came
out wrong. You just need to get the same enctype as AD issues, whatever
that is. Windows 2003 I believe will give rc4 by default (as that is the
strongest enctype it supports), but later versions can give you aes. The
instructions I linked earlier have some information on how to handle it.

> With our 2008 R2 test domain controller I see that not-yet-updated
> clients get ArcFour service tickets (and DES session keys) while new
> clients get AES service tickets (and AES session keys). I don't have a
> test AFS cell at hand though, hence the question.

I'm not sure what you mean by this, though; if there's no afs cell, I'm
not sure what clients you're talking about, and what they're receiving a
service ticket for. The client should not be able to impact the enctype
selection of the service ticket, and it can be a security issue if they
can. There is an option in AD that lets you do that, but it's a really
bad idea to turn it on unless you really really need it. (Previously
brought up here:
<http://lists.openafs.org/pipermail/openafs-info/2013-July/039763.html>)

--
Andrew Deason
[email protected]

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