[jcifs] Absence of 'automagical' WINS server resolution in jcifs when compared to smb/nmb/winbind

Fri Jul 22 20:52:38 GMT 2005

I more than okay with top posts.  :)

Chris -)-----

On Fri, Jul 22, 2005 at 04:35:12PM -0400, John Utz wrote:
> Thankyou so much for your thoughtful reply Chris!
> 
> I'll ponder it and try to figure out how i will best handle this challenge.
> 
> tnx!
> 
> johnu
> 
> (sorry 'bout the top post, working from home and reading mail from OWA instead of emacs)
> 
> -----Original Message-----
> From: Christopher R. Hertel [mailto:crh at ubiqx.mn.org]
> Sent: Fri 7/22/2005 3:56 PM
> To: John Utz
> Cc: jcifs at lists.samba.org
> Subject: Re: [jcifs] Absence of 'automagical' WINS server resolution in jcifs when compared to smb/nmb/winbind
>  
> On Fri, Jul 22, 2005 at 02:46:44PM -0400, John Utz wrote:
> > Hello jcif-rs!
> > 
> > jcifs-1.11 works wonderfully if you provide it with some relatively
> > explicit facts concerning WINS and the domain controller.
> > 
> > in addition to the name of the domain, i need to correctly fill out
> > 
> >  jcifs.netbios.wins 
> > 
> > and 
> > 
> >  jcifs.smb.client.domainController.
> > 
> > 
> > I run smb/nmb/winbind on the same computer. I do not need to provide
> > this information to these tools, they appear to discern these facts
> > automagically.
> 
> I'm not sure how that would happen unless, perhaps, the information is
> provided via DHCP.  It has been a while, but I vaguely recall someone
> working on adding DHCP config support to Samba, but I can't see any
> reference to it in the current docs so I don't know if it's really there.
> 
> Take a look at the smb.conf file.  If there's no WINS server specified
> then my guess is that Samba is actually doing a DNS lookup.  My own
> opinion is that using the DNS for NetBIOS name resolution is messy and
> dangerous, but Windows does it so Samba does it too.
> 
> > Is there some way that i can configure jcifs to behave more like samba
> > in this respect?
> 
> Find out first how Samba is getting the information.  Either the NBNS
> (WINS server) IP is in the smb.conf file, or Samba is using the DNS.
> 
> > Placing ip information in configuration files that are located on each 
> > and every jcifs machine in the domain seems rather brittle.
> 
> That's how Windows typically does it.  You generally configure each and
> every Windows box either with a static WINS server IP address, or to
> accept whatever WINS server (NBNS) address the system is handed via DHCP.
> 
> > If forces outside of my  control decide to change the name of the 
> > domainController or the IP of the wins server, then all my jcifs boxes 
> > are broken, and nobody will be able to login to fix it because they wont 
> > be validated against the domain :-(
> 
> Likewise for Windows (unless you're using DHCP and they also update the
> DHCP server),
> 
> As for the DC, there are a couple of protocols for finding a domain 
> controller.  jCIFS can use simple name lookups to find a DC, assuming 
> NetBIOS name resolution is working.  The other protocols require RAP or 
> RPC.
> 
> > Am i correct in my understanding of how this works?
> 
> Not really.  :)
> 
> ...but you seem to have enough clue to figure it out.
> 
> I wrote a whole book on the subject, if you're interested.  The book's
> online and link is in my signature, below.
> 
> > Is this a subject that has been pondered by the jcifs developers? Is 
> > this an explicit design decision? or is this a bug that needs fixing?
> 
> It is important that jCIFS not be made reliant on things like the location 
> of the DHCP client leases file, etc.  Personally, I do wish that there 
> were an easy way to find the NBNS, but the only way to do that is:
> 
> - Find one or more Local Master Browser nodes on the local network (NBT
>   can't see outside of the local IP subnet unless it knows where the NSNS 
>   (aka. WINS server) is).
> 
> - Collect browse lists from any/all of the LMBs you've discovered.
> 
> - Search through those lists to find entries with the WINS bit set.
> 
> That's not a sure-fire approach, however.  The WINS server(s) you find may 
> not be correct for the set of machines you want to access.  It is also 
> completely possible that the NBNS isn't running any services, in which 
> case it won't register with the Browse Service.
> 
> Fun, eh?
> 
> Chris -)-----
> 
> -- 
> "Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
> Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
> jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
> ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
> OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org
> 

-- 
"Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org