samba - Dec 2022 - isc-dhcp-server issues on samba 4.17

Hello everybody!
I'm having an issue that I'm not really sure it's samba related.
Still,
here it goes to see if anyone has seen this before.
I have 2 DCs debian based that I recently upgraded from Buster to Bullseye.
One is virtual another is physical. Both running bind, and dns-dyn-updates.
dhcp in failover mode "split 128".
In parallel to the "Buster upgrade", I upgraded samba from 4.13 self
compiled to 4.16 bullseye-backports (following Rowland's suggestion, I
created a 3rd DC, then removed/installed/re-joined each DC at a time). It
all went rather well with the usual minor glitches.
In the mean time, 4.17 appeared in the backports so, I upgraded the
physical DC. And now comes my issue.
On this DC, isc-dhcp-server wont start, complaining about:
isc-dhcp-server[1453137]: /usr/sbin/dhcpd: error while loading shared
libraries: libisc-export.so.1100: cannot open shared object file: No such
file or directory
This is of course true, since bind (9.16.27) uses libisc-export.so.1105
which is there.
I've checked the configuration against the other DC (where everything
works) and they are similar. Another weird fact is that removing
isc-dhcp-server (and then apt autoremove) and then reinstalling
isc-dhcp-server makes the server work. But only until the next reboot or
systemctl restart.
Due to this last fact, I'm not really sure, where in the upgrade process,
the dhcp server stopped working.

What I did:
1) tried with a basic dhcp.conf (not failover)
2) checked dhcp and bind configuration against samba wiki and the other DC
3) changed dns backend to samba_internal and back
4) reinstalled isc-dhcp and bind9 (results in the above behaviour)
5) Disabled apparmor

What i didn't do
1) create a link for libisc-export. That would maybe solve it but its a
c****y solution.
2) remove, reinstall and re-join

I've found something that seems to be related in the debian bug reports
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=995242
Not sure it's the same issue.

Any clues? Again, not sure this is samba related or not, but truth is
everything works on the virtual DC with samba 4.16.

Best regards,
CJ

01.12.2022 15:20, Carlos Jesus via samba wrote:
> Hello everybody!
> I'm having an issue that I'm not really sure it's samba
related. Still,
> here it goes to see if anyone has seen this before.
> I have 2 DCs debian based that I recently upgraded from Buster to Bullseye.
> One is virtual another is physical. Both running bind, and dns-dyn-updates.
> dhcp in failover mode "split 128".
> In parallel to the "Buster upgrade", I upgraded samba from 4.13
self
> compiled to 4.16 bullseye-backports (following Rowland's suggestion, I
> created a 3rd DC, then removed/installed/re-joined each DC at a time). It
> all went rather well with the usual minor glitches.
> In the mean time, 4.17 appeared in the backports so, I upgraded the
> physical DC. And now comes my issue.
> On this DC, isc-dhcp-server wont start, complaining about:
> isc-dhcp-server[1453137]: /usr/sbin/dhcpd: error while loading shared
> libraries: libisc-export.so.1100: cannot open shared object file: No such
> file or directory
> This is of course true, since bind (9.16.27) uses libisc-export.so.1105
> which is there.
This smells like a packaging bug in either isc-dhcp-server or bind
(or in one of their library packages).

Samba packages does not link to any of these libraries and does not
use neither bind nor isc-dhcp (samba does provide dlz_bind*.so but
these aren't linked with bind libs either), neither does it Recommend
any of these. More, 4.16 is not different from 4.17 in this aspect,
they both use the same libs and has the same set of Recommends/
Depends.

That to say: you can install/upgrade/reinstall/remove samba at will,
it wont affect isc-dhcp-server in any way.
> I've checked the configuration against the other DC (where everything
> works) and they are similar. Another weird fact is that removing
> isc-dhcp-server (and then apt autoremove) and then reinstalling
> isc-dhcp-server makes the server work. But only until the next reboot or
> systemctl restart.
So you should figure out what's going on there.  There's No Magic (tm).
You can always use ldd /usr/sbin/dhcp to verify all libs it needs are
present (or not, and when exactly a lib becomes missing). You can see
which packages provides which libs, by using dpkg -S filename.

> Any clues? Again, not sure this is samba related or not, but truth is
> everything works on the virtual DC with samba 4.16.
Samba has nothing to do with this.  There's something else hitting
you. Upgrade to bullseye is a very possible cause there, - like some
packages weren't upgraded successfully, for example.

/mjt