DHCP discovery of WINS servers

[Andrew Bartlett]

I've been thinkg about this, and there are a few other issues:  
 - we now have the start of wins fail-over support, so we now cope with
multiple wins servers (in HEAD, where I would apply such a patch).
 - we don't want to be doing a dhcp operation for *every* client
operation.  While its fine to do it each time the server starts, doing
it every time a client (like smbclient) starts could be a little
overkill.
 - what if our request is lost?  UDP is lossy, should we at least make
some attempt to send a second request?

Other than that the patch looks good, but I'm a little snowed under at
the moment.

Andrew Bartlett

Shirish Kalele wrote:
> 
> I agree that using DHCPdiscover is not really kosher.
> 
> However, even DHCPdiscover cannot imply address allocation. DHCP servers
> need to get a valid response to their offer to confirm that the client
> accepted an address it offered. Since nmbd sends no such response, and since
> DHCP is based on UDP, servers are usually prepared to handle such behaviour
> (per RFC and a bit of testing). The offered address might go into the
> unofferable pool for a little while, but will be available again after no
> response is received to the offer.
> 
> So it seemed like doing DHCPdiscover if DHCPinform fails was harmless and
> covered more cases considering the number of old DHCP servers out there.
> 
> Again, this could also be a fine tuning option in smb.conf if required.
> 
> - SK
> 
> -----------------------------------------------------------------------
> Life is what's happening while you're busy planning for it. - Unknown
> 
> > >
> > > Hi,
> > >
> > > I don't know how desirable this functionality is, but here's a patch
> that
> > > uses DHCP to have Samba dynamically discover WINS servers to use (when
> > > 'wins server = dhcp' is specified in smb.conf). This can be a nice
> option
> > > to have in some situations..
> > >
> > > The patch (and included files) work with 2.0.10 and the 2.2 branch.
> >
> > I like it.  This is the kind of thing we need for seemless intergration
> > into many network environments.
> >
> > My only worry is the use of DHCPdiscover.  I'm happy with using
> > DHCPinform, as that cannot imply address allocation, but a DHCPdiscover
> > based setup could allocate addresses and really confuse the admin.  (I
> > know that this means we will fail older DHCP servers, but I'm much
> > happier with it that way.  ISC DHCPd 3.0 has supprorted it for ages, and
> > is now in Release Candidate.   I'm not sure about MS's server)
> >
> > Andrew Bartlett
> >
> > --
> > Andrew Bartlett
> > abartlet at pcug.org.au
> > abartlet at samba.org
> >

-- 
Andrew Bartlett                                 abartlet at pcug.org.au
Samba Team member, Build Farm maintainer        abartlet at samba.org
Student Network Adminstrator, Hawker College    abartlet at hawkerc.net
http://samba.org     http://build.samba.org     http://hawkerc.net