[Samba] winbind on DC : how use gidNumber instead of primaryGroupID as user's primary group

Wed Aug 21 12:33:51 UTC 2019

On 21/08/2019 09:04, Prunk Dump via samba wrote:
> Le mar. 20 août 2019 à 14:30, L.P.H. van Belle via samba
> <samba at lists.samba.org> a écrit :
>> Hai,
>>
>>> In short. My network design previously work with Debian Stretch
>>> Servers and clients and some Windows clients (not many).
>>>
>>> Debian Stretch use Samba 4.5.16 so there is no unix_primary_group
>>> option for the clients. So I have to use the "dirty" tweak of
>>> modifying all my users "primaryGroupID" to the corresponding
>>> "gidNumber". Every things works well with my NFSv4 shares and Samba
>>> shares. I did not notice somethings wrong neither in Linux or Windows
>>> client.
>> ? Uhm, samba-tool does have the option to add uid/gids.
>>
>> I can recall our conversation years ago for jessi with nfsv4.
>> These days setting up nfsv4 is easy.
>> I these days have NFSv4 with sys,krb5,krb5i,krb5p working
>> *example, ssh SSO logins and automounted krb5p and protected homedirs, which even root can not enter.
>> I'll work this out in the howto's im updating/writing atm for Debian Buster.
>> This might take some time, because it will be the full setup of how im running things.
>> .. I might speed up a bit because i noticed the samba wiki is really improved a lot,
>> so i migh "borrow" some parts ;-).
>>
>> It might help, if you can explain exactly how you nfsv4 is setup now.
>>
>>> Now my network design will be upgraded to Debian Buster. I was happy
>>> to see the apparition of the "unix_primary_group" option. I think at
>>> start that this will help me ovoiding the dirty trick.
>>>
>> I still dont understand what your exactly doing and what was not working..
>> (sorry)
>>
>>> But on the Buster Samba DC this option does not exist and more, now
>>> Samba DC refuse to check the "primaryGroupID" value. My dirty trick
>>> does not works anymore. So il need to convert all my scripts to obtain
>>> the gidNumber.
>>>
>>> Here what id give on DC :
>>> # id testteacher6
>>> uid=4000007(FICHLAN\testteacher6) gid=5200001(FICHLAN\domain users) groups=5200001(FICHLAN\domain users),5000002(FICHLAN\teachers),5000000(FICHLAN\s4users),3000009(BUILTIN\users)
>>>
>>> Surprisingly it seems that winbind_nss put the group corresponding to
>>> the gidNumber just after the "Domain Users" group on the "id" comment.
>>> But I'm not sure this behavior is reliable. So may the Louis tricks
>>> can work ...
>>>
>> Hmm, so, i've tested a bit more, because if Rowland says something i pay extra attention ;-).
>>
>> I create a new user with ADUC. Note, i use Win7, so i have the Unix tab. ;-)
>>
>> - clean windows AD users.
>> id testuser
>> uid=3000338(BAZRTD\testuser) gid=10000(BAZRTD\domain users) groups=10000(BAZRTD\domain users),3000338(BAZRTD\testuser),3000009(BUILTIN\users)
>>
>> net cache flush
>>
>> - Assigned a UID + Primary Group, shell.   ( testing Primary group : testgroup )
>> id testuser
>> uid=10128(NTDOM\testuser) gid=10000(NTDOM\domain users) groups=10000(NTDOM\domain users),3000009(BUILTIN\users)
>> ? no primary group/GID as i did set.
>>
>> net cache flush
>>
>> - Going to Tab :  Member of group.
>> Added group testgroup
>> Selected it, and clicked on "Set Primary Group"
>> id testuser
>> uid=10128(NTDOM\testuser) gid=10000(NTDOM\domain users) groups=10000(NTDOM\domain users),10011(NTDOM\testgroup),3000009(BUILTIN\users)
>> ? no primary group/GID as i did set.
>>
>> - going back to unix tab
>> Now here, i also selected the "primary Group", but now same as above. ( testgroup )
>> uid=10128(NTDOM\testuser) gid=10000(NTDOM\domain users) groups=10000(NTDOM\domain users),10011(NTDOM\testgroup),3000009(BUILTIN\users)
>> and again, no primary group.
>>
>> So my conclusion.
>> View point, from Linux CLI.
>> The view point from windows GUI might differ, i did not test that.
>>
>>
>> Its always :
>> UID GID PRIMIARY_GROUP_GID with the output of 'id' as far i notice with these checks.
>>
>> !! DC !!
>> On the DC, a primay group is not respected as it should.
>> And primariy group is always "domain users"
>>
>>
>> !! MEMBER !!
>> On the members, keeping the settings as it was, and working back to no uid/gid
>>
>> id testuser
>> uid=10128(testuser) gid=10011(testgroup) groups=10011(testgroup),10000(domain users),2001(BUILTIN\users)
>> Correct
>>
>> - going back to unix tab, selected "domain users"
>> id testuser
>> uid=10128(testuser) gid=10000(domain users) groups=10000(domain users),10011(testgroup),2001(BUILTIN\users)
>> # unix primary is set to "domain users" and the Windows primary group is set to testgroup.
>>
>>
>> Switching UNIX primary group and windows primary group.
>> # unix primary is set to testgroup and the Windows primary group is set to "domain users"
>> id testuser
>> uid=10128(testuser) gid=10011(testgroup) groups=10011(testgroup),10000(domain users),2001(BUILTIN\users)
>> Correct
>>
>> All set to "domain users"
>> id testuser
>> uid=10128(testuser) gid=10000(domain users) groups=10000(domain users),10011(testgroup),2001(BUILTIN\users)
>> Correct
>>
>> Remove the Unix attributed
>> id testuser
>> id: ‘testuser’: no such user
>>
>> I hope it can help you.
>>
>>
>>
>> Greetz,
>>
>> Louis
>>
>>
>> --
>> To unsubscribe from this list go to the following URL and read the
>> instructions:  https://lists.samba.org/mailman/options/samba
> Thank you very much Louis for your help !!!
>
> You have got exactly the same conclusion than me. On DC it's not
> possible to make winbind return the gid I want. And on members
> everything is coherent. (Note that the group corresponding to gid on
> DC seems to be always the first group displayed after Domain Users).
>
> And these uid/gid are used by the nfsv4 server to manage files. So if
> my nfsv4 server is on a DC :
> -> When on the member my testuser (uid=testuser, gid=teachers) create
> a file on the nfsv4 share
> -> The DC translate the user uid/gid and create a file owner by
> "testuser:domain users"
> -> If I check the file uid/gid from member I see "uid=testuser, gid=domain user"
>
> So the "problem" is that, with the nfsv4 server on DC, when my users
> create files with uid=A/gid=B, the file is created with
> uid=A,gid=Domain Users.
>
> For years I found problematic this limitation about serve files on DC.
> How do to design your network Louis to get a member file server ?
> -> You use virtualization ?
> -> You use LXC ?
> -> You use two physical servers ?
>
> How OP do in general here ? Is there some tutorial about LXC setup for
> samba around here ? I have only one physical server....
>
> @Louis :
> It's seems that we are working you and me on network design for
> school/enterprise no ? If you are interested I try to publish my work
> now :
> https://github.com/prunkdump/sclustered
>
> Maybe we can works together or exchange some part of our design. If
> you have a virtual machine emulator you can get my setup running in
> less than 30 minutes (I use puppet for configuration). If you want
> some info contact me by email.
>
> Regards,
>
> Baptiste.
>
Hi Baptiste, whilst eating my dinner, I was browsing scluster again  
(really think that's a bad name, but it is your project ;-) ) and I 
found this in samba_conf.sh.erb:

# add gid attribute to Domain Users #
echo "\
dn: CN=Domain Users,CN=Users,<%= @base_dn %>
changetype: modify
add:objectclass
objectclass: posixGroup
-
add: gidnumber
gidnumber: 100
" > /tmp/Domain_Users.ldif

My first thoughts were: NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

Why are you doing this ? You have just stopped the winbind 'ad' backend 
working on a Unix domain member unless you set a stupidly low 'idmap 
config DOMAIN' range start and if you do set it low so that domain users 
are shown, you will either overwrite a lot of the Unix system users and 
groups, or your domain users will not be shown.

You also should not add the posixGroup objectclass, it isn't required.

Sorry to sound so negative :-(

Rowland