[Bug 236830] Re: cifs does not support kerberos authentication

Steve Langasek steve.langasek at canonical.com
Mon Jun 9 22:23:05 BST 2008

Sorry, I'm afraid this bug is going to become something of a dumping
ground for my investigations; this is getting complicated enough that I
need somewhere to keep track of all the bits and pieces needed to get
this working (...almost).

Software needed:
 - 2.6.24 kernel with the CONFIG_CIFS_EXPERIMENTAL and CONFIG_CIFS_UPCALL options set
 - backported cifs.spnego upcall helper from samba 3.2
 - keyutils package (from universe)

Install the cifs.spnego helper as /usr/sbin/cifs.spnego, and add the
following line to /etc/request-key.conf (a conffile provided by the
keyutils package):

   create       cifs.spnego     *       *       /usr/sbin/cifs.spnego %k

Make sure that the default_realm value in /etc/krb5.conf points to your
AD realm; without this, I found that the kerberos upcall would fail
because it would try to retrieve the ticket via the default realm, even
if you already have a TGT in the necessary realm.  (This seems like a
regression in MIT KRB5, I don't remember this being a problem in the
past when I had correct domain_realm mappings... but chances are, anyone
who was already using smbmount w/ Kerberos has already dealt with this
problem, I guess?)

Run kinit without KRB5CCNAME set (because the kernel upcall can't set a
different ccache using an environmental variable) to request credentials
for your AD realm:

$ kinit ubuntu
Password for ubuntu at CANONICAL.LOCAL: 

Then run the mount.cifs command, specifying username=, sec=, and 'guest'
options (the misnamed 'guest' option being the way to tell mount.cifs
not to prompt for a password):

$ mount.cifs //win2003.canonical.local/ubuntu /tmp/testmount -ousername=ubuntu,sec=krb5i,guest

Following these steps, I'm able to successfully mount a share using
kerberos authentication in the cifs driver.

** Bug watch added: Debian Bug tracker #480663

** Also affects: samba (Debian) via
   Importance: Unknown
       Status: Unknown

cifs does not support kerberos authentication
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