[Samba] If a NetBIOS name used within a week is reused, an incorrect owner is returned.

[Rowland Penny]

On Wed, 12 Mar 2025 08:19:29 +0000
CHIBA HIROSHI(千葉　洋) via samba <samba at lists.samba.org> wrote:

> Hi,
> 
>  
> 
> I suspect this behavior comes from a bug. If the behavior is as
> designed, I'd like to know the background of the design. 
> 
> - Bug information
> 
> Version: 4.20.2
> 
> When a shared guest account is enabled and a NetBIOS name that was
> used within the past week is reassigned, the owner of the guest
> account becomes Account Unknown (S-1-5-21-*-501), and WRITE returns
> ACCESS_DENIED. (For example, this issue occurs when the NetBIOS name
> is changed from "AAAA" to "BBBB" and then back to "AAAA" again.) 
> 
> This behavior seems to be caused by the idmap cache.  

Well, yes, but only because you are failing to do something.

Every time you change the computers hostname, Samba issues a new SID.
Which means that your 'Account Unknown' (which actually is known, it is
'Guest') gets a new SID and when someone connects to Samba, this is
stored in the cache.

The cache is just that, it is a cache, it is not permanent.
The fix for your problem is very easy, every time you change the
hostname, clear the cache with 'net cache flush'.

Can I close your bug report ?

Rowland