[Samba] Samba 4 two DCs no matching UID/GID
Rowland Penny
rowlandpenny at googlemail.com
Thu Dec 11 02:56:32 MST 2014
On 10/12/14 21:53, Tim wrote:
>
> Am 10. Dezember 2014 22:26:52 MEZ, schrieb Rowland Penny <rowlandpenny at googlemail.com>:
>> On 10/12/14 21:05, Tim wrote:
>>> Thanks for your answer and time you offer for me. That makes it a bit
>>> clearer.
>>>
>>> I searched the web and found that rsat needs to have the nis tools
>>> installed.
>> Good luck with trying to install 'Service for NIS', it installs on a
>> windows AD DC, you haven't got a windows AD DC, you have a Samba AD DC
>> and guess what, it already has the core of 'Service for NIS'
>> installed,
> I meant the nis tools feature for getting the Unix attributes tab in rsat/ADUC. Sorry that I was misunderstood.
>
>>> Does it create Unix uid/gid automatically then?
>> NO NO
>>
>>> Without rfc2307 information it makes no sense to me to have a *nix
>>> machine for file services and another one for backup purposes, when
>>> uid and gid are not same (due to preserve acls).
>>> And for now the xid is set on the FS.
>> Hard luck, that is just the way it is, **WHY* *do you think that it is
>> recommended to not use the DC as a fileserver ???
>>
>>> I haven't created a user or group with rsat nis tools enabled yet.
>> But
>>> I strongly hope that nis information will be generated automatically
>>> in the AD then. I'll try it tomorrow.
>> If you use the UNIX_Attributes tab in ADUC to give your users
>> 'uidNumbers' etc, then it is likely that you will start at '10000'.
> That's what I will do.
>
>> Once
>> you give your first user a 'uidNumber' then the next ID number will be
>> stored in AD.
> Just to be sure: So once a user got the first uid in Unix tab in ADUC all new created users or groups with ADUC will get assigned a uid/gid automatically in Unix attributes tab?
>
> For now, no user or group created with ADUC (without NIS tools installed) got an id in Unix tab. It's just empty.
>
>>> Manual setting these attributes will not be comfortable and could be
>>> forgotten when creating a new user or group. In the end filesystem
>>> permissions on different filers will be corrupt - especially when one
>>> DC will crash.
>> That is why I am advising you to use ADUC, it is either that or writing
>>
>> your own bash script around samba-tool or the ldb-tools.
>>
>> Rowland
>>
>>> Am 10. Dezember 2014 20:58:06 MEZ, schrieb Rowland Penny
>>> <rowlandpenny at googlemail.com>:
>>>
>>> On 10/12/14 18:58, Tim wrote:
>>>> At the moment numbers start at 3000000 and counting. In my eyes
>>>> it would make sense, that these number be stored in the AD when
>>>> provisioned with rfc2307. Or it should be replicated by drs.
>>> The numbers you are seeing are coming from idmap.ldb, now as you
>>> are using Sernet packages on Centos7, this will be in
>>> /var/lib/samba/private/idmap.ldb. The number 3000000 is an
>>> xidNumber and is the result of samba4 mapping SID-RID to
>> something
>>> that Unix will understand.
>>> If you just used the Samba4 AD DC for authentication and didn't
>>> store *anything* on the DC, you wouldn't need 'xidNumbers',
>>> 'uidNumbers' or 'gidNumbers', but then there is 'Sysvol'. You
>> need
>>> this for GPO's etc, but again, access is only allowed by windows
>>> users, so the xidNumbers are sufficient. I hope you can see, if
>>> you only have windows users, you only need rfc2307 attributes
>> when
>>> you store users files on the DC.
>>>
>>> As for storing Unix ID numbers in AD when provisioning with
>>> rfc2307, this does not and will not happen, Windows does not give
>>> users the rfc2307 attributes when 'Service for NIS' is added to
>> AD
>>> and for a very good reason, all users might not require them.
>>>
>>>>
>> https://wiki.samba.org/index.php/Using_RFC2307_on_a_Samba_DC#Configuring_RFC2307_and_NIS_Extensions_in_a_Samba_AD
>>>> says the following:
>>>> No need for manual ID counting when using the default Microsoft
>>>> tools. E. g. the next free UID and GID is stored directly in
>>>> Active Directory and will be incremented when creating a new
>> user
>>>> or group.
>>>>
>>>> But what is needed for this? Manual setting of NIS domain in
>> Unix
>>>> attributes?
>>> If you create your users with samba-tool on the DC, one of the
>>> options is '--uid-number=', but you have to enter the number
>>> yourself, samba-tool has nowhere to store the next uidNumber.
>>>
>>>> The problem chapter describes my situation - but both DC have
>> set
>>>> idmap_ldb:use rfc2307 = yes
>>>>
>>> The setting just tells the DC to use rfc2307, it does not set
>> any,
>>> as I said, this is done by idmap.ldb, only problem is that the
>>> xidNumbers for a user are not forced to be the same on **both**
>> DC's
>>> Rowland
>>>
>>>> I forgot to say that my server is CentOS 7 with most recent
>>>> SerNet Samba 4.1.13
>>>>
>>>>
>>>>
>>>> Am 10. Dezember 2014 19:25:50 MEZ, schrieb Rowland Penny
>>>> <rowlandpenny at googlemail.com>:
>>>>
>>>> On 10/12/14 17:30, Tim wrote:
>>>>> I will try this tomorrow. Possibly this is my fix.
>>>>>
>>>>> When a domain is provisioned with rfc2307 it would make
>>>>> sense that Unix attributes especially uid/gid would
>>>>> automatically be set.
>>>> This is a common misconception, it does not happen, one
>>>> reason being, what number do you start at ??
>>>>
>>>>> A member also needs this to be set for unique fs acls
>> right?
>>>> This is where winbind works if there are RFC2307 attributes
>>>> in AD, it can be set up to pull all the required attributes
>>>> from AD, this is one of the reasons that it is recommended
>> to
>>>> use member servers with a DC.
>>>>
>>>> Rowland
>>>>
>>>>> Am 10. Dezember 2014 18:07:02 MEZ, schrieb Rowland Penny
>>>>> <rowlandpenny at googlemail.com>:
>>>>>
>>>>> On 10/12/14 16:33, Tim wrote:
>>>>>> I think I will only need uid and gid due to fs stuff.
>>>>>> There are only Windows clients in that domain.
>>>>>> So when the IDs are the same on both DCs, all will be
>>>>>> fine I think.
>>>>>>
>>>>>> In RSAT there are no Unix attributes set. As an
>>>>>> example: user1 has uid 3000021 on DC1 (first
>>>>>> provisioned one). DRS seems fine. On DC2 user1 gets
>> uid
>>>>>> 3000017.
>>>>>> If I set ID in RSAT Unix attributes after choosing
>>>>>> domain, the IDs mentioned above will be overwritten?
>>>>>> Standard in Unix attributes is that ID is not set.
>> E.g.
>>>>>> I set ID 2000021 in RSAT this ID will be set for user1
>>>>>> on both DCs because of use rfc2307 = yes?
>>>>>>
>>>>>> Regards
>>>>>> Tim
>>>>>>
>>>>>> Am 10. Dezember 2014 16:10:58 MEZ, schrieb Rowland
>>>>>> Penny <rowlandpenny at googlemail.com>:
>>>>>>
>>>>>> On 10/12/14 14:39, Tim wrote:
>>>>>>
>>>>>> I found this. But I didn't find it related to
>>>>>> DC idmapping replication. I have two pieces of
>>>>>> hardware. My goal is realize an active
>>>>>> directory for the windows clients and a file
>>>>>> server. The AD should have redundancy (this is
>>>>>> why I provisioned two DCs). The file should
>>>>>> integrate snapshots like a NetApp system
>>>>>> (snapshots are done by rsnapshot). The
>> snapshot
>>>>>> functionality works so far by mounting cifs
>>>>>> shares read only of the backup hardware. But I
>>>>>> will try this via NFS due to permissions.
>>>>>> Mounting cifs shares leads to irritating
>>>>>> permissions of ~snapshot folders ("Everyone"
>>>>>> has full permissions). So how would sssd help
>>>>>> to replicate the ids regarding idmapping to
>> the
>>>>>> secondary DC? It seems that this is my only
>>>>>> problem. Another option is to have only one DC
>>>>>> with NFS regarding snapshots and a file server
>>>>>> who is integrating the snapshots as mentioned
>>>>>> above. But then I have to backup the idmapping
>>>>>> file of the file server or does it get the ids
>>>>>> from the AD DC so that I don't have to backup?
>>>>>> The FS stores the ACL by using the IDs. I am
>>>>>> using XFS. Thanks in advance Tim Am 10.
>>>>>> Dezember 2014 13:48:40 MEZ, schrieb Rowland
>>>>>> Penny <rowlandpenny at googlemail.com>: On
>>>>>> 10/12/14 12:21, rintimtim at gmx.net wrote:
>> Thanks
>>>>>> for the advice of copying the idmap.ldb. That
>>>>>> works. After adding zum users the uid and gid
>>>>>> begin to differ again. I read that it is not
>>>>>> recommended to run a DC as a fileserver but in
>>>>>> my case it's not really an option. It's a
>>>>>> network of twelve clients, so four servers are
>>>>>> incommensurate to this amount of clients. I
>>>>>> searched regarding sssd, because my
>>>>>> nsswitch.conf also has it. But how do I have
>> to
>>>>>> configure it all? My actual nsswitch.conf
>>>>>> provides the following: passwd: files sss
>>>>>> shadow: files sss group: files sss services:
>>>>>> files sss netgroup: files sss Another
>>>>>> alternative seems to be regarding the
>> idmap.ldb
>>>>>> with my unidirectional rsync replication of
>> the
>>>>>> sysvol-folder. *Gesendet:* Mittwoch, 10.
>>>>>> Dezember 2014 um 11:01 Uhr *Von:* "Rowland
>>>>>> Penny" <rowlandpenny at googlemail.com> *An:* Tim
>>>>>> <rintimtim at gmx.net>, samba at lists.samba.org
>>>>>> *Betreff:* Re: [Samba] Samba 4 two DCs no
>>>>>> matching UID/GID On 09/12/14 22:49, Tim wrote:
>>>>>> But will this idmap.ldb change work for
>>>>>> upcoming new users or groups so that uid/gid
>>>>>> will not be different? The wiki tells us about
>>>>>> built-in groups. Those have the right ids. Am
>>>>>> 9. Dezember 2014 23:03:44 MEZ, schrieb Rowland
>>>>>> Penny <rowlandpenny at googlemail.com>: On
>>>>>> 09/12/14 21:07, Tim wrote: Hello all, I have a
>>>>>> fresh install of two CentOS 7 machines. On DC1
>>>>>> I made a domain provision with --use-rfc2307.
>>>>>> In DC2 I made a join as DC - both exactly as
>>>>>> the wiki advised. In fact of its missing I
>>>>>> added the idmap use rfc2307 yes parameter to
>>>>>> smb.conf. I will have an extra share on both
>>>>>> DCs. Today I realized, that wbinfo shows
>>>>>> different UID/GID for the same users or groups
>>>>>> on the DC's. I created the users/groups via
>>>>>> RSAT. I don't have a Unix attributes tab in
>>>>>> RSAT. Is that my problem for different
>> uid/gid?
>>>>>> Thanks in advance Tim Hi, I think your problem
>>>>>> is that idmap.ldb does not replicate to the
>> new
>>>>>> DC, this means that users get different UID's
>>>>>> on the two DC's. If you run: ldbedit -e nano
>> -H
>>>>>> /var/lib/samba/private/idmap.ldb on each DC,
>>>>>> you will be able to see the differences. The
>>>>>> cure ? copy idmap.ldb from the first DC to any
>>>>>> secondary DC's after the join. It is
>> documented
>>>>>> here:
>>>>>>
>> https://wiki.samba.org/index.php/Join_a_domain_as_a_DC
>>>>>> , near the bottom of the page. Rowland I take
>>>>>> it that you didn't read this page on the wiki:
>>>>>>
>> https://wiki.samba.org/index.php/Samba_AD_DC_HOWTO
>>>>>> You are running into one of the problems why
>> it
>>>>>> is not recommended to use the DC as a
>>>>>> fileserver, you have two choices here, either
>>>>>> set up a separate member server to use as a
>>>>>> fileserver, or use sssd or nlscd to pull the
>>>>>> RFC2307 attributes that you will need to add
>> to
>>>>>> the users/groups. Whatever you do, you will
>>>>>> need to copy idmap.ldb to any secondary DC's.
>>>>>> Rowland Did you search on the samba wiki ????
>> :
>>>>>>
>> https://wiki.samba.org/index.php/Local_user_management_and_authentication/sssd
>>>>>> Rowland
>>>>>>
>>>>>>
>>>>>>
>>>>>> OK, another
>> wikipage:https://wiki.samba.org/index.php/RFC2307_backend
>>>>>> The only way to ensure that your users have
>> consistent uidNumbers &
>>>>>> gidNumbers on **any** Unix machine, is to use the
>> RFC2307 attributes.
>>>>>> The attributes are all available out of the box
>> with Samba4, you just
>>>>>> have to give your users and groups the required
>> attributes.
>>>>>> Once you have given your users & groups these
>> attributes, you then have
>>>>>> to use something to pull these attributes. Winbind
>> is available from
>>>>>> Samba, but winbind on the DC is different from the
>> winbind that is used
>>>>>> on a member server or client. The winbind that is
>> available on the DC
>>>>>> will not pull any RFC2307 attributes other than
>> 'uidNumber' &
>>>>>> 'gidNumber'. What this means is, if you want to
>> use different
>>>>>> unixHomeDirectories & loginShell's, you need to
>> use sssd or nlscd.
>>>>>> Rowland
>>>>>>
>>>>> By default, no users have a uidNumber and no groups
>> have
>>>>> a gidNumber. If you use the UNIX_Attributes tab in
>> ADUC,
>>>>> the default start number is 10000, though you can
>> change
>>>>> this, I wouldn't bother. Just update any users via
>> ADUC,
>>>>> AD will then store the next uidNumber (or gidNumber)
>> for
>>>>> you. If you then go to the DC and run 'getent passwd
>>>>> <the user you just updated on ADUC>', you will find
>> that
>>>>> the users ID number will have changed to whatever you
>>>>> used in ADUC. This same command should give the same
>>>>> result on the second DC, though there may be a problem
>>>>> on both DC's if the cache hasn't cleared, if so, wait a
>>>>> short while, or run 'net cache flush'.
>>>>>
>>>>> If you update users with ADUC, do not add users with
>>>>> samba-tool and try to add the users uidNumber at the
>>>>> same time, you could use a number that is already in
>> use
>>>>> for another user. You can use the same number for a
>>>>> group as a user, they are different objects.
>>>>>
>>>>> If you do use ADUC to add the users uidNumber and the
>>>>> user already has any info stored on the DC, you will
>>>>> need to change the ownership of this info to the user
>>>>> (the info will show as belonging to the users old
>>>>> uidNumber).
>>>>>
>>>>> Rowland
>>>>>
OK, lets sort your problem of having an empty unix tab:
Install ldb-tools if not already installed.
Create an ldif file, call it something like update.ldif
dn:
CN=<lowercase-domain-name>,CN=ypservers,CN=ypServ30,CN=RpcServices,CN=System,DC=example,DC=com
changetype: modify
replace: msSFU30MaxUidNumber
msSFU30MaxUidNumber: <start number>
-
changetype: modify
replace: msSFU30MaxGidNumber
msSFU30MaxGidNumber: <start number>
replace <lowercase-domain-name> with your domain/workgroup name.
replace DC=example,DC=com with your rootdse.
replace <start number> with the number that you want your ID numbers to
start at.
Now add the ldif:
ldbmodify --url=/var/lib/samba/private/sam.ldb /path/to/your/ldif
replace /path/to/your/ldif with the path to your ldif i.e. if your ldif
is in roots dir and you named it as suggested '/root/update.ldif'
You may also have to change the path to sam.ldb.
If you now go to ADUC and open a UNIX_Attribute tab, it should now
contain an ID number.
Rowland
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