Режим security = share
устарел с Samba 3.6 и был удален из кода Samba в феврале 2012 года (commit d7bb961859a350):
s3-auth: Remove security=share (depricated since 3.6).
This patch removes security=share, which Samba implemented by matching
the per-share password provided by the client in the Tree Connect with
a selection of usernames supplied by the client, the smb.conf or
guessed from the environment.
The rationale for the removal is that for the bulk of security=share
users, we just we need a very simple way to run a 'trust the network'
Samba server, where users mark shares as guest ok. This is still
supported, and the smb.conf options are documented at
https://wiki.samba.org/index.php/Public_Samba_Server
At the same time, this closes the door on one of the most arcane areas
of Samba authentication.