[Samba] flood of (auth in progress) connections from unresponsive windows client crashing samba

[David Walling]

We have been experiencing a debilitating 'bug' in samba where something is causing a flood of the messages seen below in smbstatus and the network drives ( in our case N: ) on all clients become unresponsive.  In fact, the entire client becomes unresponsive, essentially making them unusable until samba is restarted.  We first saw this and connected it to the following open bug in samba (https://bugzilla.samba.org/show_bug.cgi?id=11720).  However, after mitigating the issue by removing root_squash from the nfs mount, things stabilized for awhile, but we still see this symptom occur occasionally.  One reproducible way to trigger it was to try and use the network drive as the user library install location in R/Rstudio.  After informing all users not to do that, things seemed to stabilize again, but we are still seeing this occur every other day or so at seemingly random times.  Most of our users on the clients are using Stata16 to access data on the mapped drive.

The only additional clue is from the log.clienthostname file and is: ""lookup_name_smbconf for clienthostname$ failed".  This appears to show the client trying to connect as itself and not a specific user.  I cannot confirm if this is actually related to the core issue or simply a coincidence.

We are running samba v4.8.3 on Centos v7.6.1810 and our clients are Windows Server 2016.

Has anyone experienced something similar in smbstatus?  Do you know of any good consultants who could help us resolve this crucial issue?  Any help is greatly appreciated.

Samba version 4.8.3
PID     Username     Group        Machine                                   Protocol Version  Encryption           Signing
----------------------------------------------------------------------------------------------------------------------------------------
10741   (auth in progress)    redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10730   user1           G-234    redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10730  user2            G-234    redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10752   (auth in progress)     redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10769   (auth in progress)     redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10730   user3            G-234    redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10771   (auth in progress)     redacted (ipv4:redacted)      SMB3_11                                                partial(AES-128-CMAC)
10781   (auth in progress)     redacted (ipv4:redacted)      SMB3_11                                                 partial(AES-128-CMAC)

Thanks,

David Walling