[Samba] Different behavior when client uses "sec=none" and when provides bad user (mapped to guest)

Carlos Alberto Balseiro Mayi balseiro at balseiro.org.es
Fri Jan 17 21:32:03 UTC 2025



HI everyone.

I've been analyzing a problem with an embedded Linux/FPGA device that in some cases was failing to run properly when using files from a samba share. After some time I've found it is related to Samba bug 12783 and setting kernel oplocks on global fix the issue. 

But while looking at that I have found a strange behavior I can't understand. I have guest ok = yes on the share and map to guest = Bad User on global.

If I mount the share with a bad user, everything works OK and I can see the device lock on the file with smbstatus.

But if I mount the samba share with sec=none , the program will throw an error, I think because it wasn't able to adquire a lock on the file - I don't see a lock in smbstatus.

In both cases the connection is assigned to nobody, as configured for guest connections. I run samba 4.20.5 on Truenas Scale 24.10 . I have attached to this mail:

- the output of testparm -s

- the audit logs provided by Truenas when I connect with bad user and with sec=none

- the smbstatus when connected with bad user and with sec=none

Any idea what can be happening?

Best Regards,

Carlos A. Balseiro









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