[Samba] Restricting AD group logging on to Servers

[Roy Eastwood]

> -----Original Message-----
> From: Rowland Penny [mailto:rpenny at samba.org]
> Sent: 01 December 2017 17:40
> To: samba at lists.samba.org
> Cc: Roy Eastwood
> Subject: Re: [Samba] Restricting AD group logging on to Servers
> 
> On Fri, 1 Dec 2017 17:06:42 -0000
> Roy Eastwood via samba <samba at lists.samba.org> wrote:
> 
> > Hi,
> > I have a Debian Stretch system running a self-compiled version 4.7.3
> > of Samba.     Having followed the Samba WiKi to allow AD users to log
> > onto the servers using PAM authentication, I now want to restrict
> > access to specified group(s).   So I created a linuxadmins group and
> > made some test users members of the group.
> >
> > Initially I tried to restrict access by
> > modifying /etc/security/access.conf and adding a file
> > to /usr/share/pam-configs containing Auth: required pam_access.so.
> > This works OK for normal users, including AD users, but I cannot get
> > it to work for AD groups.   For example, I wanted to deny Domain
> > Users, but allow linuxadmins.     I have tried all variations eg
> > DOMAIN\Domain Users, DOMAIN\\Domain Users, Domain Users, domain
> > users;    in quotes or not, with () as per the man page but cannot
> > get this to work - ie no matter what I enter all AD users are allowed
> > to log in (using SSH).
> >
> > Searching the net I found reference to the pam_winbind.conf file
> > in /etc/security.    This did not exist, so I created a file
> > containing the line: require_membership_of=DOMAIN\\linuxadmins   but
> > this has no effect.   The man pages for pam_winbind and
> > pam_winbind.conf indicate it has been built for Samba v4.7 but states
> > "is correct for version 3 of Samba".   So I assume it's no longer
> > used for version 4?
> >
> > On member servers, setting the user's shell to /bin/false in the Unix
> > Attributes tab of ADUC will prevent access, but this doesn't work for
> > the DCs as this value is ignored.
> >
> > So how can this be done?
> >
> > Many thanks,
> >
> > Roy
> >
> >
> 
> try adding the 'require_membership_of' line to the winbind auth line in
> PAM.
> 
> Rowland

Thanks Rowland, that did the trick and is the simplest solution.   

Found that only one \ was required to separate the domain part from the group name part - ie DOMAIN\linuxadmins rather than
DOMAIN\\linuxadmins.   (the man page for pam_winbind.conf suggests two \\ are needed).

Regards,
Roy