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DJoin cannot find domain controllers

Publié : 08 sept. 2026 - 09:34
par AdamBertok
Dear Tranquil IT team,

Apologies in advance for the English-language post.

I would like to ask whether anyone else has run into the following issue. I believe this may be a potential bug currently present in the WAPT console.

The symptom is as follows:
When preparing a machine with djoin under the OS Deploy tab, we get the error message "Cannot find any domain controllers for <domain>."
djoin.png
djoin.png (12.65 Kio) Consulté 251 fois
I suspect this may be related to the most recent Samba update.
BUG 15988: Samba internal DNS service doesn't handle switch from UDP to TCP when packet is larger than 4k
https://bugzilla.samba.org/show_bug.cgi?id=15988

According to the bug, Samba's internal DNS service redirects any UDP packet larger than 512 bytes to the TCP protocol.

Evidence:
Every time, I try to refresh and get domain controllers we the following traffic happen in the background.
wireshark.png
wireshark.png (3.03 Kio) Consulté 251 fois
WAPT console try to request _ldap._tcp.<domain>.
Samba internal dns response with the same payload indicating the TC flag, which should trigger TCP request from client side, but that request never happen.
In our case, the DNS response to this packet is larger than 512 bytes.
wireshark-tc.png
wireshark-tc.png (7.11 Kio) Consulté 251 fois
The nslookup _ldap._tcp.<domain> from windows or command line just working fine.

Environment:
Samba:
- Debian 13 Trixie
- Samba Version: Sernet 4.24.6-4

WAPT:
- Debian 13 Trixie
- WAPT version: 2.6.1.17765

This issue is currently affecting several of our WAPT servers. Has anyone else run into this problem as well?

Thank you in advance!