Win98 connection - MS quality/compability

Pradeepa Venkatswamy pradeepa.venkatswamy at
Fri Jan 4 20:57:02 GMT 2002


	Thank you very much for your explanation.That's really helped me to
understand the working of nmbd and smbd.

Thank you,

> -----Original Message-----
> From: Christopher R. Hertel [mailto:crh at]
> Sent: Friday, January 04, 2002 11:57 PM
> To: Esh, Andrew
> Cc: 'Pradeepa Venkatswamy'; samba-technical at
> Subject: Re: Win98 connection - MS quality/compability
> > Samba is both nmbd and smbd. It isn't just one daemon.
> >
> > The service provided by nmbd is not just an equivalent to WINS,
> or DNS. It
> > does not just implement name-to-IP conversions.
> >
> > The nmbd daemon implements NetBIOS and LanManager naming and
> browsing. It
> > performs the same function as the Network Neighborhood in
> Windows. Without
> > it, clients can't get enough information to access other
> services. The Unix
> > equivalent is a combination of DNS, NIS, LDAP(?), and probably
> a few other
> > user/host/network information services.
> Mostly, yes.
> Nmbd really does two jobs.  First, it defines the virtual NetBIOS LAN.
> ("NetBIOS LAN" is really the wrong name, since NetBIOS is an API, but the
> term applies.  The original name was "IBM PC-Network".)  Addressing in
> NetBIOS is based on 16-byte names.  The NBT layer (as implemented in
> nmbd) is responsible for mapping between NetBIOS addresses and the
> addresses of the underlying IP layer.  This is managed via a distributed
> database.  The WINS server is simply one node that participates in that
> database (and is not necessary on a single subnet).
> The other job nmbd does is handling the browsing service.  Browsing is a
> separate service that *uses* the NetBIOS virtual LAN.  Unfortunately, the
> browsing was badly designed and *is broken*, causing all sorts of trouble
> in the WINS server.  Most notably, the Local Master Browser will attempt
> to register its unique name (<workgroup>#1D) with the WINS server.  Each
> subnet needs its own LMB, so each subnet needs a machine with the name
> <workgroup>#1D registered.  Since this name is unique, it can't happen.
> Microsoft got around this by having the WINS server make a special
> exception.  WINS will accept LMB registrations, and then quietly drop the
> registration into the trash.
> > The smbd daemon is equivalent to the File and Printer Sharing service on
> > Windows. The Unix equivalent is NFS and lpd.
> >
> > The reason your test isn't working even though you are using
> the IP address
> > is, Windows uses the IP address to do a NetBIOS query to the host. It is
> > trying to resolve the NetBIOS name of the host, and gather other
> > information. Without the host name, most of the request packets
> which need
> > to be sent later can't be constructed.
> Right, but the only thing that W/9x actually needs is a recognized
> service name to satisfy the requirements of the NBT Session Service.
> That is a very, very small piece.
> Microsoft actually built a kludge to work around this requirement.  They
> introduced the "*SMBSERVER" name.
> According the RFC1001/1002, NetBIOS names in an NBT namespace may *not*
> Session Service that it could always respond positively to a session setup
> using the name "*SMBSERVER".  That name is never registered, and does not
> appear in the name list when you send an Adapter Status query.  It is an
> obvious kludge... but it is why the connection from W2K and W/NT works
> even though nmbd is not running.  Samba, in our ever-frightening efforts
> to be compatible, also accepts the "*SMBSERVER" name in session setups.
> One the session is established, NBT really isn't needed any more.  There
> are a few bytes worth of NBT Session header in the session packets.
> When Microsoft finally realized this, they came up with SMB over TCP
> using port 445.  It's almost exactly the same.
> Chris -)-----
> --
> Christopher R. Hertel -)-----                   University of Minnesota
> crh at              Networking and Telecommunications Services
>     Ideals are like stars; you will not succeed in touching them
>     with your choose them as your guides, and following
>     them you will reach your destiny.  --Carl Schultz

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