Created attachment 18481 [details] C-program source to reproduce the problem. We use Ubuntu 20.04.6 systems as Samba server. The Samba version is 4.15.13-Ubuntu. The SMC-Client is a Windows Server 2022 Standard 21H2. The relevant Samba parameters in /etc/samba/smb.conf are: security = ads realm = MAIL-STREET.LOCAL workgroup = MAIL-STREET server min protocol = SMB3_02 client min protocol = SMB3_02 smb encrypt = required server signing = mandatory The hostname of the Ubuntu Samba server is "samba-srv" On the Windows system, Samba disk is shared with the command: C:\net use Y: \\samba-srv\customers /u:hans Enter the password for 'hans' to connect to 'samba-srv': The command completed successfully Now the Samba disk on system samba-srv can be accessed on the Y-drive. The network analyzer Wireshark show that Kerberos is used to encrypt the network packages. But on the moment that Kerberos ticket renewal, the Samba share is some seconds not available. An other DNS record is created with the name "samba-srv-alias" This is a "Alias (CNAME)" to the DNS "Host (A)" "samba-srv". The Y-drive is removed and created again and now with as host "samba-srv-alias". C:\net use Y: \\samba-srv-alias\customers /u:hans Also now the Samba disk on the samba-srv can be accessed on the Y-drive. But Wireshark show now that NTLM is used to encrypt the network packages. NTLM doesn't work with tickets that need to be renewed. The problem that the Samba shared is some seconds not available doesn't occur when NTML is used to encrypt the network packages. The problem that the share is some seconds not available also doesn't occur when the share is not on Samba but on an other Windows system, also when Kerberos is used. In the attachment contains a C-program source that can be used to reproduce the problem. The source can be compiled on Windows with e.g. gcc The program read every 3 seconds a map/directory on the share to check for files and write in a logfile when the share is not available and available again. Start the hotfolderscan program e.g. on the way below: C:>hotfolderscan.exe Y:\ C:\temp\folderscan.log After +/- 10 hours, when Kerberos renew the ticket, the lines below are written in de log file: 2024-10-23 09:09:13 Error 2 No such file or directory 2024-10-23 09:09:16 Share available again Is seems that Samba doesn't handle the Kerberos ticket renewal on the right way.
(In reply to Hans van Leeuwen from comment #0) Can you please post this to the samba mailing list, it may not be a bug. When you post, please add the output of 'testparm -s' to the post. I should also point out that while Samba 4.15.13 is supported by Ubuntu on 20.04, it is EOL from the Samba point of view.