[Samba] Windows ACL clarification for Roaming Profiles share

L.P.H. van Belle belle at bazuin.nl
Mon Feb 20 08:08:56 UTC 2017

Hello Marc, 

First of all.
is really outdated. 

The Explanation is simply incomplete.
Yes, localy there is SYSTEM. But due to some i think sid/rid whatever wrong mapping its not working correctly in samba when you use GPO settings also. 
Per example. And its the last time im telling it. 
I beleave that, somewhere somehow, the explanation of the above link is used in samba coding. And the result is a not good.

For you this link: 
> > https://technet.microsoft.com/en-us/library/dd851678(v=ws.11).aspx 
Says : 
Its token includes the NT AUTHORITY\SYSTEM and BUILTIN\Administrators SIDs; these accounts have access to most system objects. The name of the account in all locales is .\LocalSystem. The name, LocalSystem or ComputerName\LocalSystem can also be used

Can you explain why i only can use system as "DOMAIN\system" here? 
When i set the user SYSTEM in my GPO and why this never works. 

So if you dont believe me.
Create a Scheduled task and try to make it run as user NT AUTHORITY\SYSTEM 

1.Viewing/Edit a GPO,
go to Computer Configuration > Control Panel Settings > Scheduled Tasks.
2.Right-click in the window and choose
New > Scheduled Task (At least Windows 7).
3.On the General tab:
a.Set the name to TestSchedule.
b.Run the task as NT AUTHORITY\System. Check Run with highest privileges.
c.Click OK.

3b, try, klik change user/group.
Next window, type : system, klik ok.
It changes to NTDOM\system which should be BUILTIN\SYSTEM

3b, again, change user/group,
Next window, type : Server Operators, and klik ok.
That reports correcty : BUILTIN\Server Operators

Resulting error: 
The computer 'Administrators (built-in)' preference item in the 'LocalAdminPolicy {77E77E2C-DD41-4BE8-BCA3-9D729ED51F98}' Group Policy object did not apply because it failed with error code '0x80070534 
No mapping between account names and security IDs was done.' This error was suppressed 

Key here is :
No mapping between account names and security IDs was done. 

Conclusion for me is. 
Sure, i beleave all your saying and everything your saying works. 
If you going to set more advanced GPO settings, it wil end up in errors,
Not working GPOs etc. 

Just my saying, said already to much here.
Posted problems like this long ago already. 

Samba DC : ( 4.5.3) 
wbinfo --lookup-sids=S-1-5-18
wbcLookupSids failed: WBC_ERR_INVALID_SID
Could not lookup SIDs S-1-5-18

Samba Member 4.5.3 and 4.5.5

For a correct windows 10 profiles share, you need the following. 
which clearly shows systems with Full control. 



> -----Oorspronkelijk bericht-----
> Van: Marc Muehlfeld [mailto:mmuehlfeld at samba.org]
> Verzonden: zaterdag 18 februari 2017 1:15
> Aan: L.P.H. van Belle; samba at lists.samba.org
> Onderwerp: Re: [Samba] Windows ACL clarification for Roaming Profiles
> share
> Hi Louis,
> Am 17.02.2017 um 09:26 schrieb L.P.H. van Belle via samba:
> >> What uses the SYSTEM principal on the Sysvol share?
>  >
> > Every computer or user the has a GPO set.
> You may be right that "computer" GPOs are applied locally using the
> SYSTEM account. However, this is _local_ and the computer does not
> access the Sysvol share using the SYSTEM account. To download the
> computer GPOs, the machine account is used to connect to the share.
> Per-user GPOs are downloaded using the user's permissions and applied to
> the user's files and registry (HKCU).
> However, I gave it a try, to see if my knowledge is meanwhile outdated:
> - I removed the SYSTEM account from the Sysvol share including from all
> subfolders.
> - I created two GPOs in the "Default domain policy":
>    - I set a different background for the logon screen (computer)
>    - I removed the "change password" entry from the
>      CTRL+ALT+DEL menu (user)
>    - I mapped the Sysvol share using GPO preferences (user)
> - I rebooted my Win10 client.
> After the reboot, the background was changed and after I logged in, the
> entry was hidden in the menu and the share connected. The Sysvol share
> works without SYSTEM account in the ACLs locally on the share.
> Give it a try if you don't believe me. :-)
> > Do read:
> > https://technet.microsoft.com/en-us/library/dd851678(v=ws.11).aspx
> > And see here, Security options :
> > Computer Configuration , by default the task is run in the security
> context of the SYSTEM account.
> This is about tasks that run locally. And locally on a Windows machine
> is where the SYSTEM account is usually used. If the local SYSTEM Account
> tries to access a network resource, it uses the machine account to
> authenticate.
> That's why it is not necessary to add SYSTEM to the file system ACLs on
> a Samba share: SYSTEM is just an account that exists _locally_ and is
> not used when connecting to network resources.
> If you have anything (a service, a task job, etc.) running on your
> _local_ computer that uses the SYSTEM account, then SYSTEM must be of
> course added to the local file system ACLs if this task, etc. should be
> able to access _local_ files.
> Here's a nice explanation of the SYSTEM account:
> https://abhijitw.wordpress.com/2012/03/03/the-local-system-account/
> See also:
> https://msdn.microsoft.com/en-
> us/library/windows/desktop/ms684190%28v=vs.85%29.aspx
> https://support.microsoft.com/en-us/help/120929/how-the-system-account-is-
> used-in-windows
> Regards,
> Marc

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