[Freeipa-users] interesting Kerberos issue

[Nathaniel McCallum]

On Mon, 2015-05-18 at 17:03 +0300, Alexander Bokovoy wrote:
> On Mon, 18 May 2015, Janelle wrote:
> > On 5/10/15 11:57 PM, Alexander Bokovoy wrote:
> > > On Sun, 10 May 2015, Janelle wrote:
> > > > On 5/5/15 6:47 AM, Dmitri Pal wrote:
> > > > > On 05/04/2015 09:38 PM, Janelle wrote:
> > > > > > On 5/4/15 6:06 PM, Nathaniel McCallum wrote:
> > > > > > > On Mon, 2015-05-04 at 08:49 -0700, Janelle wrote:
> > > > > > > > Happy Star Wars Day!
> > > > > > > > May the Fourth be with you!
> > > > > > > > 
> > > > > > > > So I have a strange Kerberos problem trying to figure 
> > > > > > > > out. On a
> > > > > > > > CLIENT,  (CentOS 7.1) if I login to account "usera" 
> > > > > > > > they get a
> > > > > > > > ticket as
> > > > > > > > expected.  However, if I login to a 6.6 client, it 
> > > > > > > > doesn't seem to
> > > > > > > > work.
> > > > > > > > Both were enrolled the same, obviously one is newer.
> > > > > > > > 
> > > > > > > > Now, it gets stranger. The "servers" are CentOS 7.1 
> > > > > > > > also. If I login
> > > > > > > > as
> > > > > > > > root, bypassing kerberos, and then do "kinit admin" it 
> > > > > > > > works just
> > > > > > > > fine.
> > > > > > > > But if I do "kinit usera" I get:
> > > > > > > > 
> > > > > > > > kinit: Generic preauthentication failure while getting 
> > > > > > > > initial
> > > > > > > > credentials
> > > > > > > > 
> > > > > > > > Which makes no sense. The account works with a 7.1 
> > > > > > > > client but not a
> > > > > > > > 6.x
> > > > > > > > client?? And yet "admin" works, no matter what. What am 
> > > > > > > > I missing
> > > > > > > > here?
> > > > > > > If I had to guess, usera is enabled for OTP-only login. 
> > > > > > > Is that
> > > > > > > correct?
> > > > > > > 
> > > > > > > If so, clients require RHEL 7.1 for OTP support. Also, 
> > > > > > > the error you
> > > > > > > are getting is the result of not enabling FAST support 
> > > > > > > for OTP
> > > > > > > authentication (see the -T option).
> > > > > > > 
> > > > > > > Nathaniel
> > > > > > Ok, this did give me an idea (Thanks Nathaniel)  -- the 
> > > > > > account was set for BOTH "password" and OTP.
> > > > > > Apparently setting both does nothing. Yes a user can login 
> > > > > > with their password-only, but trying to use kinit does not 
> > > > > > work.
> > > > > > 
> > > > > > I am not sure I understand where the FAST support or the -T 
> > > > > > 
> > > > > > option is to be applied. On kinit? That does not seem 
> > > > > > correct. 
> > > > > > Perhaps I am misunderstanding this option?
> > > > > > 
> > > > > > ~J
> > > > > > 
> > > > > If the user is enabled for OTP his credential are sent 
> > > > > differently than in the case when it is not enabled. 
> > > > > Effectively 
> > > > > instead of using encrypted timestamp the password and OTP are 
> > > > > 
> > > > > sent to the server as data. But they can't be sent in clear. 
> > > > > You 
> > > > > need to encrypt the data. To encrypt it you need another key 
> > > > > - 
> > > > > the host key. The encryption of the data in this context is 
> > > > > called tunneling . FAST is the Kerberos protocol feature to 
> > > > > provide tunneling of the data sent over the wire. To use FAST 
> > > > > 
> > > > > one needs to use -T on the kinit command line.
> > > > > Does this help?
> > > > > 
> > > > It helps -- thank you.
> > > > 
> > > > Now allow me to add a little more fun, and there may not be a 
> > > > solution.
> > > > > From OS X (Yosemite) I am able to "kinit --kdc-hostname=IPA
> > > > > -server
> > > > principal" and it works, gives me a ticket, and if I attempt to 
> > > > 
> > > > login to the web interface, since I already have my ticket - 
> > > > boom, 
> > > > works fine.
> > > > 
> > > > Now, I enable 2FA and setup a token and change my account to 
> > > > OTP 
> > > > (with TOTP).  But as previously discussed, can't seem to 
> > > > specify a 
> > > > -T option from OS X.
> > > > 
> > > > I know this sounds tricky -- Any ideas?
> > > Use
> > > kinit --fast-armor-cache /path/to/ccache to specify already 
> > > existing ccache to armor the FAST processing.
> > > 
> > > This is Heimdal-specific, and you should have Heimdal 1.6rc2 at 
> > > least.
> > > You can check version number by running 'kinit --version'.
> > Aha, so thee default on OS X Yosemite is
> > 
> > $ kinit --version
> > kinit (Heimdal 1.5.1apple1)
> > 
> > so this won't work?
> Yes, you have to have the feature in your Kerberos library.

Browsing the Heimdal source code, I don't even see any support for OTP
at all. :(

Nathaniel