Samba and krb5.conf

[Kenny Dinh]

I added
   export KRB5_CONFIG=/home/krb5.conf
   echo "KRB5_CONFIG is $KRB5_CONFIG"

into /etc/init.d/smb, /etc/init.d/winbind as well as /etc/init.d/ctdb.
That fixed my issue.

It took me some times to verify that because I forgot to add the EV
KRB5_CONFIG to winbind start script, and also forgot to change permission
on the /home/krb5.conf file, in the first few times.

Thank you, Richard, and Simo.
Your help was much appreciated.
~Kenny



On Fri, Apr 17, 2015 at 4:20 PM, Richard Sharpe <realrichardsharpe at gmail.com
> wrote:

> On Fri, Apr 17, 2015 at 3:16 PM, Kenny Dinh <kdinh at peaxy.net> wrote:
> >
> >> Set the environment variable KRB5_CONFIG to another file in the samba
> >> unit file/startup script ?
> >
> > I'm not sure I understood this approach.  Could you help elaborate?  Are
> you
> > referring to Samba4/InitScript or the /etc/rc.d/init.d/smb script file?
> > My understanding is that smbd is run as a service so all environment
> > variables such as KRB5_CONFIG will be discarded.
>
> Since your environment is CentOS 6.x, you probably want to put
> something like the following in the Samba start script for CentOS 6.x:
>
>    export KRB5_CONFIG=/path/to/empty/krb5.conf
>
> > On Fri, Apr 17, 2015 at 3:02 PM, Simo <simo at samba.org> wrote:
> >>
> >> On Fri, 2015-04-17 at 14:16 -0700, Kenny Dinh wrote:
> >> > Richard,
> >> >
> >> > It is possible to run the conflicting application in a container, but
> I
> >> > cannot prevent future applications.
> >> >
> >> > I will look into the alternative method, make the kerberos libraries
> >> > linked
> >> > to Samba use a different location of krb5.conf rather than
> >> > /etc/krb5.conf.
> >> > I have been looking at the wrong place all this time.
> >> >
> >> > Thanks for the pointer!
> >> > ~Kenny
> >>
> >> Set the environment variable KRB5_CONFIG to another file in the samba
> >> unit file/startup script ?
> >>
> >> Simo.
> >>
> >> > On Fri, Apr 17, 2015 at 2:02 PM, Richard Sharpe
> >> > <realrichardsharpe at gmail.com
> >> > > wrote:
> >> >
> >> > > On Fri, Apr 17, 2015 at 1:09 PM, Kenny Dinh <kdinh at peaxy.net>
> wrote:
> >> > > > Greeting,
> >> > > >
> >> > > > We are using Samba 4.1.13 on CentOS and was having issue
> >> > > > authenticating
> >> > > > user that was created in a subdomain.
> >> > > >
> >> > > > We found out that another application had updated the
> /etc/krb5.conf
> >> > > > to
> >> > > > match its need, and Samba was not happy about it.  When we deleted
> >> > > > the
> >> > > > /etc/krb5.conf, Samba was able to authenticate user from a
> subdomain
> >> > > > (smbclient //localhost/share -U<subdomain>\\<user>%<password>)
> >> > > >
> >> > > > Note that SAMBA4_USES_HEIMDAL was not defined.
> >> > > > This is my smb.conf
> >> > > >
> >> > > > # net conf list
> >> > > > [global]
> >> > > > idmap config *:backend = tdb
> >> > > > idmap config *:range = 1000000-100000000
> >> > > > idmap config *:script = /usr/mydir/bin/idmap
> >> > > > workgroup = REPUBLIC
> >> > > > realm = REPUBLIC.WINDC
> >> > > > security = ads
> >> > > > netbios name = testbox1
> >> > > > log level = 10
> >> > > >
> >> > > > [blah]
> >> > > > path = /
> >> > > > comment = sdakjhkjh
> >> > > > guest ok = no
> >> > > > read only = no
> >> > > > browseable = yes
> >> > > >
> >> > > > I noticed that the code path went
> >> > > > through create_local_private_krb5_conf_for_domain() function and
> >> > > > created
> >> > > > its own krb5.conf.  Toward the end of the function, the code also
> >> > > > set the
> >> > > > KRB5_CONFIG environment variable to "
> >> > > > /var/lib/samba/smb_krb5/krb5.conf.REPUBLIC"
> >> > > >
> >> > > > Here's a snippet of the log:
> >> > > > /var/log/samba/log.smbd:[2015/04/17 10:19:25.083196,  5, pid=9003,
> >> > > > effective(0, 0), real(0, 0)]
> >> > > >
> >> > >
> >> > >
> ../source3/libads/kerberos.c:925(create_local_private_krb5_conf_for_domain)
> >> > > > /var/log/samba/log.smbd:
> create_local_private_krb5_conf_for_domain:
> >> > > wrote
> >> > > > file /var/lib/samba/smb_krb5/krb5.conf.REPUBLIC with realm
> >> > > > REPUBLIC.WINDC
> >> > > > KDC list = kdc = 10.0.3.1
> >> > > >
> >> > > > I searched through samba code for krb5.conf and found that
> >> > > > "krb5_config_file" in source4\heimdal\lib\krb5\constants.c seems
> to
> >> > > > be
> >> > > the
> >> > > > only place that make use of krb5.conf files location.  Also the
> >> > > > function
> >> > > > where "krb5_config_file" is used in krb5_init_context() defined in
> >> > > > source4\heimdal\lib\krb5\context.c.  However, it seems that the
> code
> >> > > > was
> >> > > > never executed.  I place additional DEBUG message in that code
> path
> >> > > > but
> >> > > > none appear.
> >> > > >
> >> > > > This is the variable I was referring to.
> >> > > > KRB5_LIB_VARIABLE const char *krb5_config_file =
> >> > > >
> >> > > > It seems Samba expects the default location for krb5.conf to be
> >> > > > located
> >> > > at
> >> > > > /etc/krb5.conf.  However, I couldn't find the location in the code
> >> > > > where
> >> > > > Samba is looking for /etc/krb5.conf.  Another thing that confuses
> me
> >> > > > is
> >> > > why
> >> > > > does Samba look into /etc/krb5.conf when it was already creating
> its
> >> > > > own
> >> > > > krb5.conf file.
> >> > > >
> >> > > > My goal is to prevent Samba from looking at /etc/krb5.conf to
> avoid
> >> > > > conflicts between Samba and any other applications that would
> modify
> >> > > > /etc/krb5.conf.
> >> > > >
> >> > > > Could someone point me to the code to do that?
> >> > >
> >> > > It's likely the kerberos libraries that are looking in that file.
> >> > > Samba really works best if you tell it to use DNS to look up
> services
> >> > > and realms, so an empty krb5.conf file works.
> >> > >
> >> > > However, if you need a krb5.conf for another application, is it
> >> > > possible to run that application in a jail or container?
> >> > >
> >> > > Alternatively, you might have to make the kerberos libraries linked
> to
> >> > > Samba use a different location or not use krb5.conf.
> >> > >
> >> > > --
> >> > > Regards,
> >> > > Richard Sharpe
> >> > > (何以解憂？唯有杜康。--曹操)
> >> > >
> >>
> >>
> >> --
> >> Simo Sorce
> >>
> >
>
>
>
> --
> Regards,
> Richard Sharpe
> (何以解憂？唯有杜康。--曹操)
>