[Samba] Questions for minimal AD DC, DNS setup and Posix use

Andrew Bartlett abartlet at samba.org
Thu Jan 31 04:56:28 MST 2013

On Thu, 2013-01-31 at 16:55 +1100, Dewayne wrote:
> Our plan is to have one AD DC running in Head Office, RODC's at Branches and a second writeable DC at a contingency site. Fileshares
> will run on separate servers.  The Windows 2003/2008 Servers use authentication services from samba4 and run applications.  Our
> current environment is Samba-3.6.9 PDC,BDCs & fileshares, openldap stores samba, posix and acts as heimdal backend - for SSO.
> My questions are:
> Are smbd and winbindd necessary on the AD DC.  I would prefer to start samba with only what it needs to function. When I kill the
> smbd and winbindd processes, the kerberos, ldap & dns functionality remain. How can I produce a minimal AD DC:
> 1) Do I need smbd to parse the smb.conf for samba4 to start correctly?

on the AD DC, you start only 'samba'.  We may start other binaries or
provide services via plugins, but you only have to start 'samba'. 

> 2) If not, is there a better way than "kill -9" to achieve the result of samba4 without smbd, winbindd?

You should just kill the parent 'samba' process and any child processes
will notice this and go away.  As you know, in general don't generally
kill -9 stuff, as something may be in progress.  I think tdb is safe for
kill -9 these days, but it has always been best not to do this as a
first choice. 

> For readers new to RODC, this is useful: http://technet.microsoft.com/en-us/library/cc772234(v=ws.10).aspx
> DNS is required in Samba4 AD DC as explained here http://blog.tridgell.net/?p=122 (Coming from a samba3 background, Tridge's article
> is informative).
> The internal DNS works like a dream. However the internal DNS doesn't slave to a master DNS, so --dns-backend=BIND9_DLZ is the best
> option for a complex environment using Windows servers as members or DC's. However:

You can always forward to another DC, or have your complex DNS server
point only a particular domain to Samba, say with a bind zone of type

> 3) For Samba4 AD DC to act purely as an authentication engine, within a UNIX only servers where PCs and WinServers are effectively
> desktops for users; can I use --dns-backend=NONE without loss of DRS or RODC functionality. (Or are these contradictory
> requirements).

No, DNS is always required, even for our internal use. 

> 4) If we need to redesign our DNS infrastructure, is it sufficient that a dhcp server, provide updates to bind9-DLZ (as a component
> of Samba4 AD DC)?

There is discussion on the list about ways to make DHCP work.  I would
like to make this 'just work' using the normal TSIG code for both the
bind9 and the internal server, but this remains a development task for
an interested developer.  (Warning, some crypto required). 

> Posix
> In a Samba3 world, I rely upon  smbldap-tools (http://gna.org/projects/smbldap-tools) to manipulate user/group information,
> including assignment of uidNumber/gidNumber that is unique to an individual, per IT audit instruction.
> I would greatly appreciate guidance on how to set/use posix on Samba4.  I've spent 4 hours trolling the web and mailing list
> searches with hints or scripts, so
> 5) Do I need to manually add the ldap posixAccount object to each users' ldap record, or is there an option in samba-tool user
> create that I haven't found?  Next issue is how to manage as the uidNumber/gidNumber content?
> {This was being worked: http://samba.2283325.n4.nabble.com/Enabling-idmap-ldb-use-rfc2307-yes-on-2-DCs-td4637386.html ?}

Yes, samba-tool is tested as being able to manage this.  4.0.3 will be a
little easier in this regard, the posixAccount/posixGroup requirement
has been dropped.

> 6) Is there any mechanism that allows me to change the uid's being assigned to files that are created by Samba AD DC to being the
> same as pre-existing uid's used by Samba3.  For example changing uid 3000020 to 1046, or gid 3000019 to 1001? 

Set those uid values on the LDAP directory using uidNumber and
gidNumber, and set 'idmap_ldb:use rfc2307=yes'. 

> Miscellaineous
> 7) Will the list of smb.conf options described in samba4 source folder source4/TODO be updated to reflect what appears in "testparm
> -vss"?  It's a little confusing as to which takes precedence?

Yes, this is confusing.  Even the output of testparm -v and samba-tool
testparm -v do not match up, and that TODO list refers mostly to the
more limited capabilities of the ntvfs file server, which is available
and supported, but is not the default.  We essentially need to transform
these details into manpage notes. 

Andrew Bartlett

Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org

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