[Samba] samba-tool hangs on one dc

Thomas Schachtner Thomas.schachtner at eltheim.de
Tue Nov 21 14:15:31 UTC 2023


Hello,

since some time (I don't remember since when) I have a strange 
phenomenon with one of my two samba4 DCs.
Both dc1 and dc2 seem to run pretty fine and when working with Windows, 
I do not see any issues.

But when issuing the following command on dc1, the command does not 
return but seems to be stuck.

samba-tool drs showrepl

When issuing the same command on dc2, it takes a second or so and the 
result is printed on the screen.
The same with other commands like "samba-tool dns add"

I already checked the samba log files, but I did not find any log entry.

I know that it is difficult to provide a solution for a problem that is 
described so poorly, but I don't know how to further debug it.
Any hints on how to move forward here and/or how to get more information?

The output of samba-tool drs showrepl on dc2 does not show issues, 
regardless of which dc is replicated to which one (i.e. dc1 to tc2 or 
vice-versa).
When executing repadmin /replsummary on a Windows client, also no errors 
are shown.

Here's the output:

root at dc2:/var/lib/samba# samba-tool drs showrepl
Default-First-Site-Name\DC2
DSA Options: 0x00000001
DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
DSA invocationId: 0e649cb7-efc8-47ad-a841-4453973dbcec

==== INBOUND NEIGHBORS ====

DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ Tue Nov 21 12:26:25 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:26:25 2023 CET

CN=Schema,CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ Tue Nov 21 12:26:25 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:26:25 2023 CET

CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ Tue Nov 21 12:26:25 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:26:25 2023 CET

DC=DomainDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ Tue Nov 21 12:26:25 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:26:25 2023 CET

DC=ForestDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ Tue Nov 21 12:26:25 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:26:25 2023 CET

==== OUTBOUND NEIGHBORS ====

DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

CN=Schema,CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

DC=DomainDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

DC=ForestDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC1 via RPC
                 DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

==== KCC CONNECTION OBJECTS ====

Connection --
         Connection name: 138dbf8f-16ef-406e-87aa-72a25b4e03b6
         Enabled        : TRUE
         Server DNS name : dc1.local.example.de
         Server DN name  : CN=NTDS 
Settings,CN=DC1,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=local,DC=example,DC=de
                 TransportType: RPC
                 options: 0x00000001
Warning: No NC replicated for Connection!

Now, after 10 minutes or so, also dc1 finished the command.
Here's the result:

root at dc1:~# samba-tool drs showrepl
Default-First-Site-Name\DC1
DSA Options: 0x00000001
DSA object GUID: 4872003f-2bd7-4393-9eed-1ceaeecf92eb
DSA invocationId: a1e3fc90-833a-476e-8c8a-0753b5593ae3

==== INBOUND NEIGHBORS ====

DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ Tue Nov 21 12:41:42 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:41:42 2023 CET

CN=Schema,CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ Tue Nov 21 12:41:43 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:41:43 2023 CET

CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ Tue Nov 21 12:41:43 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:41:43 2023 CET

DC=DomainDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ Tue Nov 21 12:41:43 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:41:43 2023 CET

DC=ForestDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ Tue Nov 21 12:41:41 2023 CET was successful
                 0 consecutive failure(s).
                 Last success @ Tue Nov 21 12:41:41 2023 CET

==== OUTBOUND NEIGHBORS ====

DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

CN=Schema,CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

CN=Configuration,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

DC=DomainDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

DC=ForestDnsZones,DC=local,DC=example,DC=de
         Default-First-Site-Name\DC2 via RPC
                 DSA object GUID: e4cf97f3-ad31-4a1d-bb3d-00a0db86e6a8
                 Last attempt @ NTTIME(0) was successful
                 0 consecutive failure(s).
                 Last success @ NTTIME(0)

==== KCC CONNECTION OBJECTS ====

Connection --
         Connection name: 85d23471-63cd-4bf1-9238-1ea493d07a95
         Enabled        : TRUE
         Server DNS name : dc2.local.example.de
         Server DN name  : CN=NTDS 
Settings,CN=DC2,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=local,DC=example,DC=de
                 TransportType: RPC
                 options: 0x00000001
Warning: No NC replicated for Connection!



Both servers (Ubuntu Server) have the latest updates installed.
The samba version is 4.15.13-Ubuntu.

What could be the reason why one dc takes so long with samba-tool 
commands while the other one is much faster?

Best
Tom


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