SMB File Sharing on Big Sur reverts to default permissions automatically

Question

Running Big Sur 11.5 and trying to use File Sharing to access my drive on my local network. I only wish to allow the primary user access so I set the permissions accordingly ("everyone" has no access).

However, after ~1 day (hard to figure out exactly when), the permissions will revert, allowing anyone read access which is the default setting. This occurs without rebooting, the only operations being connecting to the SMB share and waiting some amount of time.

Is there something I'm doing wrong with the configuration? I've looked into alternative network file sharing servers (even just brew install samba) but can't find anything with good documentation besides the native SMB file sharing.

Answer 1

If you want to use samba from homebrew, try this basic smb.conf

[global]
ea support = yes
mdns name = mdns
security = user
min protocol = SMB2
vfs objects = fruit streams_xattr
fruit:metadata = stream
fruit:model = MacSamba
fruit:posix_rename = yes 
fruit:veto_appledouble = no
fruit:wipe_intentionally_left_blank_rfork = yes 
fruit:delete_empty_adfiles = yes
fruit:time machine = yes
aio read size = 1 
aio write size = 1

[MacTimeMachineBackup]
comment = Mac Time Machine Backup
path = /srv/smb/mactimemachinebackup
writeable = yes
vfs objects = fruit streams_xattr
fruit:time machine = yes

In my experience (once properly set up) Samba from homebrew is more forgiving across different versions of MacOS and filesystems.