[Samba] Upgrading from Samba 4.8.2 to 4.15.5

[Rowland Penny]

On 28/01/2023 06:44, Mark Foley via samba wrote:
> I wrote earlier about setting the domain user password minimum to > 14
> characters. It was advised that my first step should be to upgrade from Samba
> 4.8.2 to the most recent version available which for my Slackware 15.0 distro is
> 4.15.5. This also involved a distro upgrade from Slackware 14.2 to 15.0.
> 
> After upgrading, just for the heck of it, I tried starting Samba without
> changing my 4.8.2 configs.  Of course, that didn't work.  My initial error (of
> several) in syslog was:
> 
> Jan 28 00:42:52 mail krb5kdc[2725]: Cannot open DB2 database '/var/kerberos/krb5kdc/principal': No such file or directory - while initializing database for realm MYDOM.LOCAL

That looks like you also installed a MIT kerberos server as well, a 
Samba domain usually uses the Heimdal kerberos server it comes with.

> 
> At that point I decided to read the Wiki: https://wiki.samba.org/index.php/Setting_up_Samba_as_an_Active_Directory_Domain_Controller#Introduction
> 
> Under "Only Applicable if Samba was Previously Installed", it is telling me to
> deleted all my carefully crafted config files and looks like it's going to lead
> me through the steps of re-provisioning.
> 
> Before taking that step I thought I'd ask if I really need to do that? Can I not
> just install krb5, etc. and get there step-wise without redoing especially my
> /var/lib/samba/private/ named.conf and dns/ files, and re-provisioning?
> 
> Thanks --Mark
> 

That wiki page is indeed for setting up a new domain, to join another 
DC, you need this page:

https://wiki.samba.org/index.php/Joining_a_Samba_DC_to_an_Existing_Active_Directory

But before you do anything, I would check if you are running a separate 
kdc and if you are, stop and remove it.
I do hope you are doing this on a different machine to your existing DC.

Rowland