Transferring NFSv4 nfs/ keys from KDC to client?
steve
steve at steve-ss.com
Thu Mar 20 05:49:52 EDT 2014
On Thu, 2014-03-20 at 00:52 +0100, Wendy Lin wrote:
> On 20 March 2014 00:04, Wendy Lin <wendlin1974 at gmail.com> wrote:
> > On 19 March 2014 23:36, steve <steve at steve-ss.com> wrote:
> >> On Wed, 2014-03-19 at 23:16 +0100, Wendy Lin wrote:
> >>> On 19 March 2014 14:11, steve <steve at steve-ss.com> wrote:
> >>> > On Wed, 2014-03-19 at 13:32 +0100, Wendy Lin wrote:
> >>> >> On 19 March 2014 09:55, steve <steve at steve-ss.com> wrote:
> >>> >> > On Wed, 2014-03-19 at 00:09 +0100, Wendy Lin wrote:
> >>> >> >> On 18 March 2014 23:54, steve <steve at steve-ss.com> wrote:
> >>> >> >> > On Tue, 2014-03-18 at 23:20 +0100, Wendy Lin wrote:
> >>> >> >> >> Asking here to make sure I got the mechanism right:
> >>> >> >> >>
> >>> >> >> >> I created the principal nfs/china.mytest.org at TEST1.MYTEST.ORG on the
> >>> >> >> >> KDC machine so that NFSv4 client china.mytest.org can mount a NFSv4
> >>> >> >> >> filesystem.
> >>> >> >> >>
> >>> >> >> >> How does the client china.mytest.org now get the keys?
> >>> >> >> >
> >>> >> >> > Hi
> >>> >> >> > It doesn't need to. rpc.gssd can use any of the following keys:
> >>> >> >> > <HOSTNAME>$@<REALM>
> >>> >> >> > root/<hostname>@<REALM>
> >>> >> >> > nfs/<hostname>@<REALM>
> >>> >> >> > host/<hostname>@<REALM>
> >>> >> >> > root/<anyname>@<REALM>
> >>> >> >> > nfs/<anyname>@<REALM>
> >>> >> >> > host/<anyname>@<REALM>
> >>> >> >> >
> >>> >> >> > Just make sure that your keytab has one of them. Usually it will already
> >>> >> >> > have the CHINA$ key, so you can mount using that. The nfs server keytab
> >>> >> >> > should have both the nfs servivce and machine keys.
> >>> >> >> >
> >>> >> >> > There are many misunderstandings about kerberized nfs:
> >>> >> >> > http://linuxcostablanca.blogspot.com.es/2012/02/nfsv4-myths-and-legends.html
> >>> >> >> > HTH
> >>> >> >> > Steve
> >>> >> >>
> >>> >> >> What I did is:
> >>> >> >> 1. Have kadmind running on the kdc
> >>> >> >> 2. Run kadmin on the client as user root. A principal root@<REALM> exists
> >>> >> >> 3. Use ktadd in kamin to download the keys for
> >>> >> >> nfs/<clienthostname>@<REALM> and host/<clienthostname>@<REALM> .
> >>> >> >>
> >>> >> >> Still it does not work here and the mount fails:
> >>> >> >> mount -t nfs4 test1.mytest.org:/ /mnt
> >>> >> >> mount.nfs4: access denied by server while mounting nexentapuzzle.nrubsig.org:/
> >>> >> >
> >>> >> > Tell it to use Kerberos:
> >>> >> > mount -t nfs4 test1.mytest.org:/ /mnt -osec=krb5
> >>> >> >>
> >>> >> >> gssd is running:
> >>> >> >> # ps -ef | fgrep gss
> >>> >> >> root 1403 1 0 Mar18 ? 00:00:00 /usr/sbin/rpc.svcgssd
> >>> >> >> root 1420 1 0 Mar18 ? 00:00:00 /usr/sbin/rpc.gssd
> >>> >> >>
> >>> >> >> I have not a clue what I am doing wrong. Please help.
> >>> >> >
> >>> >> > Tell it to use Kerberos:
> >>> >> > mount -t nfs4 test1.mytest.org:/ /mnt -osec=krb5
> >>> >> >
> >>> >> > If still nothing send the output of:
> >>> >> > klist -ke
> >>> >> > on both the client and the server?
> >>> >>
> >>> >> @(nfs|krb) server (hostname "test1.mytest.org"):
> >>> >> # klist -ke /etc/krb5.keytab
> >>> >> Keytab name: WRFILE:/etc/krb5.keytab
> >>> >> KVNO Principal
> >>> >> ---- --------------------------------------------------------------------------
> >>> >> 2 nfs/test1 at TEST1.MYTEST.ORG (DES cbc mode with CRC-32)
> >>> >> 2 nfs/test1.mytest.org at TEST1.MYTEST.ORG (DES cbc mode with CRC-32)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 3 host/china.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 3 host/china.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 3 host/china.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 3 host/china.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 host/test1.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 host/china.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 2 nfs/test1.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 nfs/test1.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 nfs/test1.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 nfs/test1.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >> 2 nfs/china.mytest.org at TEST1.MYTEST.ORG (AES-256 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 nfs/china.mytest.org at TEST1.MYTEST.ORG (AES-128 CTS mode with
> >>> >> 96-bit SHA-1 HMAC)
> >>> >> 2 nfs/china.mytest.org at TEST1.MYTEST.ORG (Triple DES cbc mode with HMAC/sha1)
> >>> >> 2 nfs/china.mytest.org at TEST1.MYTEST.ORG (ArcFour with HMAC/md5)
> >>> >>
> >>> >> Why do I have duplicate entries in this output? Are they harmful?
> >>> >
> >>> > They represent the different encryption types. They're not harmful but
> >>> > as this is the server, there is no need for the client keys. You can
> >>> > tidy it up using e.g. ktutil.
> >>> >>
> >>> >>
> >>> >> @(nfs|krb) client (hostname "china.mytest.org"):
> >>> >> # klist -ke
> >>> >> Keytab name: FILE:/etc/krb5.keytab
> >>> >> klist: No such file or directory while starting keytab scan
> >>> >>
> >>> >> Client is my problem, how can I get the keys to it? ssh them over?
> >>> >
> >>> > Working on the kdc, create a keytab (as you did above) with the machine
> >>> > key of the client, CHINA$, If you use ktutil, something like:
> >>> > wkt /tmp/china.keytab
> >>> >
> >>> > Then simply copy it to the client using scp or (even easier and more
> >>> > secure) using a USB memory stick. Rename china.keytab to krb5.keytab and
> >>> > copy it 0600 to /etc
> >>> >
> >>> >>
> >>> >> >
> >>> >> > What does /etc/exports look like on the server?
> >>> >>
> >>> >> # cat /etc/exports
> >>> >> /nfsv4krbtest *(sec=krb5,rw,fsid=0
> >>> >
> >>> > Lose the fsid0. For now, replace the * with the IP of china
> >>> >
> >>> >> # uname -a
> >>> >> Linux test1.mytest.org 2.6.34.10-0.6-desktop #1 SMP PREEMPT 2011-12-13
> >>> >> 18:27:38 +0100 x86_64 x86_64 x86_64 GNU/Linux
> >>> >>
> >>> >> > Note that it is no longer recommended to export nfs4 as a fsid=0 pseudo
> >>> >> > root. Simply export it as we always have done nfs3.
> >>> >>
> >>> >> is this recommendation valid for the quite old 2.6.34.10-0.6-desktop
> >>> >> kernel in Suse 11.3?
> >>> >
> >>> > Dunno. Must it be nfs4 for anything in particular? Security perhaps?
> >>> > nfs3 works fine with kerberos.
> >>>
> >>> NFSv4 is better for going through a firewall and is less sensitive to
> >>> hacking attempts.
> >>>
> >>> But:
> >>> if I try to mount the share from the client I now see this:
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:03:42 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:03:43 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:03:43 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:03:43 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:03:44 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:03:44 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:03:44 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:04:29 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: ERROR:
> >>> prepare_krb5_rfc_cfx_buffer: not implemented
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: ERROR: failed serializing
> >>> krb5 context for kernel
> >>> Mar 19 23:04:30 test1 rpc.svcgssd[5154]: WARNING: handle_nullreq:
> >>> serialize_context_for_kernel failed
> >>>
> >> It doesn't like the encryption type. (On openSUSE 13.1 it's been fixed)
> >> Try:
> >> allow_weak_crypto = true
> >> permitted_enctypes = "des-cbc-crc arcfour-hmac des3-cbc-sha1
> >> aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha1-96"
> >>
> >> to [libdefaults] in /etc/krb5.conf
> >
> > I have this now for [libdefaults]:
> >
> > ---------------------------------------------------
> > [libdefaults]
> > # default_realm = EXAMPLE.COM
> >
> > default_realm = TEST1.MYTEST.ORG
> > clockskew = 300
> > allow_weak_crypto = true
> > permitted_enctypes = "des-cbc-crc arcfour-hmac des3-cbc-sha1
> > aes128-cts-hmac-sha1-96 aes256-cts-hmac-sha1-96"
> > ---------------------------------------------------
> >
> > is this what you wished to suggest? Client has the same
> > permitted_enctypes, and I did a hard reboot of all machines.
> >
> > Unfortunately it does not work. Neither does this change+mount with NFSv3 btw
>
> I tried permitted_enctypes = "des-cbc-crc des3-cbc-sha1" but this only
> gives me a new kind of (its mocking me?!) error message in
> /var/log/messages on the server:
>
> rpc.svcgssd[6967]: qword_eol: fflush failed: errno 38 (Function not implemented)
>
> Wendy
mv the keytab on the server and recreate it with TEST1$ and
nfs/test1.mytest.org only.
Same on the client but with only CHINA$
Next, let's have a look at it:
rpc.gssd -fvvv
and
rpc.idmapd -fvvv
This may tell us something.
Oh, and your DNS hs to be _perfect_.
Cheers,
Steve
(Have you yelled at the server yet?)
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