Hi All,
I'm having a bit of difficulty getting a CentOS 5.5 Kerberized NFSv4
server working. This server is configured as a Winbind client to a
Windows 2003 Active Directory. I've successfully bound it to AD and I am
able to authenticate. I've successfully created a NFSv4 entry in
/etc/exports to export the /exports directory and I can successfully mount
a non-Kerberized NFSv4 mount on a client machine. I now want to take it
to the next step and add Kerberos and it doesn't seem to be working for
me. Below are my configurations and the steps I performed.
Fresh install of CentOS 5.5. Non-Kickstarted. Wanted to get it working
manually first.
Used the First Boot Authentication Wizard to configure Winbind Support for
User Information.
Configured Winbind and Kerberos under the Authentication Tab
Checked Local auth is sufficient and Create home directories under options
The computer successfully joins the domain and appears in the Computer
container in AD. Below is the extract from /etc/samba/smb.conf for
authconfig plus what I changed, everything else is stock.
I disabled the firewall and SELinux is running in permissive mode on both
the test server and test client.
#======================= Global Settings =====================================
[global]
#--authconfig--start-line--
# Generated by authconfig on 2010/07/01 18:32:54
# DO NOT EDIT THIS SECTION (delimited by --start-line--/--end-line--)
# Any modification may be deleted or altered by authconfig in future
workgroup = MY.AD.NAME
password server = MY.AD.SERVER
realm = MY.AD.NAME
security = ads
idmap uid = 16777216-33554431
idmap gid = 16777216-33554431
template shell = /bin/bash
#--authconfig--end-line--
#-- my additions/changes-start --
template homedir = /home/%U
winbind use default domain = true
winbind offline logon = true
winbind nested groups = true
winbind refresh tickets = true
use spnego = yes
use kerberos keytab = yes
#-- my additions/changes-end --
It also created an appropriate, I believe, /etc/krb5.conf to which I
removed only the .example.com stuff resulting in the following file.
[logging]
default = FILE:/var/log/krb5libs.log
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log
[libdefaults]
default_realm = MY.AD.NAME
dns_lookup_realm = false # with and without true tried for these
dns_lookup_kdc = false
ticket_lifetime = 24h
forwardable = yes
[realms]
MY.AD.NAME = {
kdc = MY.AD.SERVER
admin_server = MY.AD.SERVER
kdc = MY.AD.SERVER
}
[domain_realm]
my.ad.name = MY.AD.NAME
.my.ad.name = MY.AD.NAME
[appdefaults]
pam = {
debug = false
ticket_lifetime = 36000
renew_lifetime = 36000
forwardable = true
krb4_convert = false
}
If I log into this host I am properly issued a Kerberos ticket from AD so
it would appear that Kerberos is working properly
[jpeltier at oak ~]$ ssh aconite klist
jpeltier at aconite's password:
klist: You have no tickets cached
Ticket cache: FILE:/tmp/krb5cc_16777216_ltvWwy
Default principal: jpeltier at MY.AD.NAME
Valid starting Expires Service principal
07/02/10 10:46:43 07/02/10 20:46:43 krbtgt/MY.AD.NAME at MY.AD.NAME
renew until 07/02/10 20:46:43
Kerberos 4 ticket cache: /tmp/tkt16777216
[jpeltier at oak ~]$
Now I configured NFSv4 exports on the server
/exports *(rw,fsid=0)
Edited /etc/sysconfig/nfs to change
# Set to turn on Secure NFS mounts.
#SECURE_NFS="yes"
to
# Set to turn on Secure NFS mounts.
SECURE_NFS="yes"
restarted NFS service and it appears as an export
[root at aconite ~]# /etc/init.d/nfs restart
Shutting down NFS mountd: [ OK ]
Shutting down NFS daemon: [ OK ]
Shutting down NFS quotas: [ OK ]
Shutting down NFS services: [ OK ]
Shutting down RPC svcgssd: [ OK ]
Starting RPC svcgssd: [ OK ]
Starting NFS services: [ OK ]
Starting NFS quotas: [ OK ]
Starting NFS daemon: [ OK ]
Starting NFS mountd: [ OK ]
[root at aconite ~]# exportfs
/exports <world>
[root at aconite ~]#
To support NFSv4 with Kerberos security, we also need to generate service
principal for NFS:
[root at aconite ~]# net -U administrator ads keytab add nfs
which then looks like this
[root at aconite ~]# klist -k
Keytab name: FILE:/etc/krb5.keytab
KVNO Principal
---- --------------------------------------------------------------------------
3 host/aconite.my.ad.name at MY.AD.NAME
3 host/aconite.my.ad.name at MY.AD.NAME
3 host/aconite.my.ad.name at MY.AD.NAME
3 host/aconite at MY.AD.NAME
3 host/aconite at MY.AD.NAME
3 host/aconite at MY.AD.NAME
3 ACONITE$@MY.AD.NAME
3 ACONITE$@MY.AD.NAME
3 ACONITE$@MY.AD.NAME
3 nfs/aconite.my.ad.name at MY.AD.NAME
3 nfs/aconite.my.ad.name at MY.AD.NAME
3 nfs/aconite.my.ad.name at MY.AD.NAME
3 nfs/aconite at MY.AD.NAME
3 nfs/aconite at MY.AD.NAME
3 nfs/aconite at MY.AD.NAME
Test on the client
[root at celastrina ~]# showmount -e aconite
Export list for aconite:
/exports *
[root at celastrina ~]# mount -t nfs4 aconite:/ /mnt
[root at celastrina ~]# mount |grep -i nfs4
aconite:/ on /mnt type nfs4 (rw,addr=199.60.1.84)
[root at celastrina ~]#
So as you can see everything is now working *without* Kerberos. However,
if I change the /etc/exports file on aconite to
[root at aconite ~]# cat /etc/exports
/exports gss/krb5(rw,fsid=0)
[root at aconite ~]# exportfs
/exports gss/krb5
and then try to mount with the -o sec=krb5 on the client
[root at celastrina ~]# mount -t nfs4 -o sec=krb5 aconite:/ /mnt
mount.nfs4: Permission denied
and the entry in /var/log/messages on celastrina is
Jul 2 11:21:57 celastrina rpc.gssd[3302]: Using keytab file
'/etc/krb5.keytab'
Jul 2 11:21:57 celastrina rpc.gssd[3302]: WARNING: Failed to obtain
machine credentials for connection to server aconite.my.ad.name
nothing appears in the logs on aconite.
If you've been kind enough to read this entire thread could you be kind
enough to let me know what I am missing or doing wrong? It seems so close
now that I can taste it, but this one last piece doesn't seem to want to
fall into place. :(
--
James A. Peltier
Systems Analyst (FASNet), VIVARIUM Technical Director
HPC Coordinator
Simon Fraser University - Burnaby Campus
Phone : 778-782-6573
Fax : 778-782-3045
E-Mail : jpeltier at sfu.ca
Website : http://www.fas.sfu.ca | http://vivarium.cs.sfu.ca
http://blogs.sfu.ca/people/jpeltier
MSN : subatomic_spam at hotmail.com
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