I would need some advice on an Ubuntu 20.04.6 Desktop with cifs-utils that suddenly stopped mounting all of our company smb shares.
The machine is joined to our AD domain through sssd, krb5 and realmd and is on the same subnet as the smb servers. I was using pam_mount with cifs-utils to automount the smb shares for our network users and it was working flawlessly until a couple of weeks ago. I've been trying to figure out the issue since then without any luck and I have a couple of other desktops and VMs with the exact same config and they are still mounting the shares without issue. Here is what's happening and what I have tried so far:
When I log locally or via SSH on the desktop with my network account, I receive the following messages in terminal:
(pam_mount.c:522): mount of company/shared/smb failed
(mount.c:72): Messages from underlying mount program:
(mount.c:76): mount error: Server abruptly closed the connection.
(mount.c:76): This can happen if the server does not support the SMB version you are trying to use.
(mount.c:76): The default SMB version recently changed from SMB1 to SMB2.1 and above. Try mounting with vers=1.0.
(mount.c:76): mount error(112): Host is down
(mount.c:76): Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)
(pam_mount.c:522): mount of share failed
So I have tried to switch smb version (even though all other workstations are currently working with version 2.1) for the mounts in /etc/security/pam_mount.conf.xml but I always receive this error. I've tried every possible version.
If I simply try to list the shares from the server with smbclient:
smbclient -L myshare.domain.com -U user -m SMB3
protocol negotiation failed: NT_STATUS_CONNECTION_DISCONNECTED
I've tried with every possible version with the same results. dmesg and /var/log/syslog ain't giving much more information.
For my tests, I've disabled ufw and antivirus agent on the problematic desktop. I can resolve the host name of the share, I can ping it, I can telnet on port 139 and 445. The team responsible for the smb share ain't seeing anything specific on their side and won't give much help since the issue is only on this specific desktop. I have tried to completely reinstall cifs-utils and libpam-mount. I am a bit at a loss here. There is a lot of data on that desktop so I would not like not to have to wipe it.
Any ideas on what else I could try would be greatly appreciated?
Thanks
