[Samba] DNS problems (still) with Linux domain members - using Samba's internal DNS backend

Gary Dale gary at extremeground.com
Tue Apr 25 18:37:26 UTC 2023

On 2023-04-25 12:01, Rowland Penny via samba wrote:
> On 25/04/2023 16:34, Gary Dale via samba wrote:
>> On 2023-04-25 07:30, Rowland Penny via samba wrote:
>>> On 25/04/2023 04:56, Gary Dale via samba wrote:
>>>> which is owned by root:Domain Admins. This shows up in Linux as:
>>>> root at TheLibrarian:~# ls -l /srv/
>>>> total 4
>>>> drwxr-xr-x 2 root 110512 4096 Apr 23 11:30 taxes
>>> Why is the group being shown as a number rather than by name (which 
>>> ends in '512' so is probably Domain Admins, which shouldn't have a 
>>> gidNumber, it breaks sysvol when using the 'ad idmap backend)
>>> Is /etc/nsswitch.conf setup correctly ? arre libpam-winbind and 
>>> libnss-winbind installed ?
>>> Rowland
>> Both are installed from backports (version 4.17.7).
>> /etc/nsswitch.conf reads:
>> passwd:         db files winbind systemd
>> group:          db files winbind systemd
> I had to look up what 'db' was, never come across it before, I do not 
> know who put it there, but I would remove every mention of it from 
> nsswitch.conf
>> shadow:         files
>> hosts:          files wins mdns4_minimal [NOTFOUND=return] dns mdns4 
> How did 'wins get there ? AD does not use it, so I would remove it, in 
> fact, I would remove the mdns4 stuff as well, leaving just this
> hosts:          files dns
>> mymachines
>> networks:       files
>> protocols:      db files
>> services:       db files
>> ethers:         db files
>> rpc:            db files
>> netgroup:       nis
>> I can't see any mention of any configuration for libpam-winbind.
> You do not need to configure, just install it and ensure that 
> 'winbind' is in the passwd and group lines.
>  When I
>> look at 
>> https://wiki.samba.org/index.php/Authenticating_Domain_Users_Using_PAM, 
>> there isn't much there. Under Configuring PAM, it just lists the 
>> utilities but doesn't say what you are supposed to do with them. It 
>> also shows an example for enabling SSH authentication on a Red Hat 
>> system, but I never use password authentication for SSH. I use 
>> certificates.
> That is the problem, PAM is set up differently depending on the 
> distro, so you have to refer to the distros documentation. However, 
> Debian does most of the required modifications for you, run 
> 'pam-auth-update' to see what is available and if it is already in use.
>> The man page for pam-auth-update isn't helpful but looking at the 
>> individual /etc/pam.dl files, they seem to have mention of winbind 
>> and kerberos.
>> I note that:
>> root at TheLibrarian:~# net rpc group list -U Administrator  ## same 
>> results from my workstation.
>> Password for [HOME\Administrator]:
>> Could not connect to server
> It is trying to to connect to a non-existing server on localhost, you 
> will need to use '-S <DC_hostname>'
>> The username or password was not correct.
>> Connection failed: NT_STATUS_LOGON_FAILURE
>> but the command(s) work on DC1. Both machines were joined to the 
>> domain and both show in the list of domain computers.
> Rowland
OK. Did all that. And yes, when I use the -S option, I can get the 
command to work. However, why is it even looking at localhost? The 
wbinfo --ping-dc shows that it knows the DC is DC1. Where is the net rpc 
command getting localhost from?

I'd think the the -S option is useful when you have multiple DCs and 
want to check the results from a particular one. If Samba on the file & 
print server isn't automatically going to the DC, I'd think that would 
cause a lot of problems - like the ones I'm seeing.

I might suspect that the issue had to do with the server's previous life 
as the AD DC, but I get the same thing happening on my workstation, 
which has only just had Samba installed on it and has never served files 
let alone domain accounts.

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