[KLUG Members] SuSE, Zeroconf, and the 'local' Domain

[Adam Tauno Williams]

> > Incompatible change: the resolver library treats the .local top level
> > domain as link-local domain and sends multicast DNS requests to the
> > multicast address 224.0.0.251 port 5353 instead of normal DNS
> > requests. If you already use the .local domain in your nameserver
> > configuration you will have to switch to another domain name. See
> > http://www.multicastdns.org for more information on multicast DNS.
> It took a bit of digging and reading to find out what's going on.
> Apparently, somebody decided that the unassigned top-level domain name,
> 'local', would be reserved for Zeroconf. This is a network "discovery"
> technology that's supposed to allow any device to plug into any
> (supporting) network, get itself set up, and find out what resources and
> services are available there. Deployed primarily by Apple under the name
> Rendezvous, it's apparently starting to work its way into the Linux
> community. I understand that Mandrake started shipping with support for
> it, and now it seems SuSE is going the same way.

I don't know how true "primarily by Apple" is.  ZeroConf is running on
every M$ operating system post NT4SP6.  It is running on every Max OS/X
box, and (if I recall correctly) recent Fedora distributions as well.

Honestly, the first time I saw this I was "what-the-hill".  BUT - It
Works!  These boxes, of various flavors, all find each other.  The
number of dumb (and impossible to answer) questions users ask me about
setting up their home LANs has dropped precipitously.  All a good thing
IMHO.

Internally using an unregistered DNS suffix has always been a gamble. 
I'd recommend just switching to something more esoteric that is less
likely to get the namespace bump.

> So, what does this have to do with the 'local' domain? Just this:
> instead of resolving it through the regular channels, SuSE's resolver
> library tries multicast DNS instead, as noted above. As near as I can
> tell, this is NOT a configurable option; it's written right into the
> resolver library, and that's that.

Yep.  I'm afraid your fighting the tide.  Multicast DNS is in the
resolver, the GNOME-VFS subsystem, and other places too.  This is pretty
much part & parcel 'service discovery'.

> It just really bothers me (okay, I lied about the venting) that Apple or
> whoever has gone and done this with no apparent official approval. It's
> even worse to have any Linux vendor just going along with it and forcing
> this kind of change down our throats, but I really didn't want to go on
> and on about it. What I want to do is get rid of it. SO:

Well, they went ahead and did it because currently the standards bodies
are dazed-and-confused.  Their incapable to making ANY new standards; so
what is the Internet, developers, and manufacturers to do?   Apple is
not alone,  this is enabled by default in Windows, and I believe even
AIX 5.2L now comes with ZeroConf support (I've only go lowly 5.1L).

> What I want to do is find the source for the resolver library and
> disable this new little 'feature'. My best guess is, it's in the BIND
> package, but I'm really not sure. If anyone might have a clue or two,
> they would be much appreciated.

I suspect your looking at hacking......... glibc.