security = share mode was deprecated since Samba 3.6, and has been removed from Samba code in February 2012 (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
At the same time, this closes the door on one of the most arcane areas
of Samba authentication.