[Samba] NT_STATUS_PROTOCOL_UNREACHABLE since 4.19.0

[Daniel Berteaud]

Hi. 

Just upgraded a samba DC from 4.18.6 to 4.19.0. Since then, I have a lot errors like this in my auth logs : 

[2023/09/15 10:34:13.138186, 2] ../../auth/auth_log.c:876(log_authentication_event_human_readable) 
Auth: [Kerberos KDC,ENC-TS Pre-authentication] user [(null)]\[ADM$@LAPIOLE.LOCAL] at [Fri, 15 Sep 2023 10:34:13.138164 CEST] with [aes256-cts-hmac-sha1-96] status [NT_STATUS_PROTOCOL_UNREACHABLE] workstation [(null)] remote host [ipv4:10.99.6.10:57814] mapped to [LAPIOLE]\[ADM$]. local host [NULL] 
[2023/09/15 10:34:13.149112, 3] ../../auth/auth_log.c:876(log_authentication_event_human_readable) 
Auth: [Kerberos KDC,ENC-TS Pre-authentication] user [(null)]\[ADM$@LAPIOLE. LOCAL 

] at [Fri, 15 Sep 2023 10:34:13.149085 CEST] with [aes256-cts-hmac-sha1-96] status [NT_STATUS_OK] workstation [(null)] remote host [ipv4:10.99.6.10:46228] became [LAPIOLE]\[ADM$] [S-1-5-21-3157880385-2929606428-1306126165-1108]. local host [NULL] 

Each time one of my client machine auth against the controller, there's first an NT_STATUS_PROTOCOL_UNREACHABLE, followed immediatly by a NT_STATUS_OK. 

Clients are various Linux servers (mainly Alma Linux 8 and Debian) joined to the domain with SSSD. 

Everything seems to be working, but I'm worried about those errors. Would anyone know what does this mean ? 


-- 
Daniel Berteaud