(Lack Of) Resilience Of WINS Registration

Christopher R. Hertel crh at nts.umn.edu
Tue Jan 15 11:50:06 GMT 2002

> >>>> Nick Boyce asked :
> >>>>
> >>>>> then our Sambas all drop off the map until we
> >>>>> notice (the phone calls coming in !) and restart nmbd on all the Samba
> >>>>> boxes.
> >> 
> >> Andrew Bartlett wrote :
> >>
> >> This is a old samba bug thats been known about for a *long* time.  I
> >> think sombody finally fixed it in recent 2.2.  Basically, Samba doens't
> >> re-register, it assumes that the WINS server is stable and doesn't loose
> >> entries.
> >
> > Yes, I've been told the same by others...
> Fantastic - thanks a lot folks.   IIUC, you're saying a Samba server will
> now periodically re-register ... 

Andrew B:  Is this fixed in 2.2.2?

> FWIW, are we saying this rumour about NT WINS servers "tickling" their
> clients to check for signs of life is unfounded ?

No.  It's more complicated than that.  ;)

- If the NT WINS server has "lost" entries due to a reboot, then it will
  not have the NetBIOS names and/or IP addresses of the clients--so it
  cannot "tickle" them.

- The WINS server *could* go through it's own list periodically and 
  "tickle" the clients to see if they're still there.  I don't know if
  Microsoft does this, but if they do they would need to be working from
  data contained in the WINS database.

  [Does anyone know if WINS on NT actually does something like this?]

- The client is supposed to refresh it's registration before the 
  registration times out.  It seems that Microsoft clients perform this
  periodic refresh frequently.  The timeout on the initial registration 
  is a little more than three days.  The RFCs would simply have them send 
  a refresh before the three days is up.

  [Does anyone out there know how frequently Microsoft sends a refresh to
  the NBNS?]

- The WINS server will also poke an existing client if a new client tries
  to register the same unique name.  If the previous owner does not 
  respond, then the WINS server will assume the previous owner is gone 
  and will allow the new registration to overwrite the old.

Those are the tickle-related things of which I can think.  Wierd things
happen in the real world, however, so I'm interested in learning about
anything I might be missing. 

> > This we have done for a while.  One of the reasons for the WINS.DAT file.
> > 
> >>Well for a while there we had the WINS.DAT, but still oblitorated it at 
> >>each startup ;-)
> > 
> > We did?  Ouch.
> The Doctor sez : "Always initialise your storage before using it."   ;-)

See... I *know* the code is in there to re-read WINS.DAT on start-up.  
That was the purpose of WINS.DAT.  Wiping it before reading it... ouch.

> Thanks for all the answers.  So the "re-registration" fix is in 2.2.2 ?

Dunno.  Andrew B?

> If so, I'll have another look at upgrading (I hit a compiling problem on
> Tru64 last time, as those kind enough to try to help me may remember - see
> http://lists.samba.org/pipermail/samba-technical/2001-October/031968.html).

Worth seeing if there are other True64 users out there who have fixed 
that problem or are aware of a work-around.

Chris -)-----

Christopher R. Hertel -)-----                   University of Minnesota
crh at nts.umn.edu              Networking and Telecommunications Services

    Ideals are like stars; you will not succeed in touching them
    with your hands...you choose them as your guides, and following
    them you will reach your destiny.  --Carl Schultz

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