[Pkg-utopia-maintainers] Bug#477714: avahi-daemon: Please disable IPv6 in the config file again

[Lennart Poettering]

Package: avahi-daemon
Version: 0.6.22-3
Severity: normal

Avahi in Debian should *not* be enabling IPv6 support by default. 

Why not?

- Brings no advantages. The intended audience for Zeroconf is desktop
  uses, normal people. People who don't care about IPv6. If people run
  IPv6 right now they surely should be capable of enabling support for
  it in Avahi by reconfiguring a single line in the config file, too.

- Because it doubles the network load imposed by Avahi for no gain

- Because it causes all services to show up twice in browsers: once via
  IPv6 and once via IPv4.

- Because people might see these duplicates and thus might end up
  hardcoding their code to only register services via IPv4 instead of
  leaving the protocols to Avahi. Thus in the long run if the time comes
  to enable IPv6 by default you'd first have to fix all those apps.

- Because it is a big deviation from how other distros do it.

- Because I am upstream and I kindly ask you to disable it. Please,
  please, With cream on top! ;-)

- Instead of enabling IPv6 support in Avahi in Debian prematurely you guys
  should first fix the remaining issues.

- Because you guys don't follow my nicely figured out plan to adopt IPv6
  in Avahi. (see below)

The road to IPv6 for Avahi should be:

- Implement some logic so that duplicates are filtered out from browse
  requests. This is harder than it sounds but would be very useful for
  multihomed hosts or hosts with VPNs, too.

- Add a config option to selectively a) disable IPv6 completely b)
  register AAAA RRs via IPv4, but don't use IPv6 as addresses, c)
  register services by IPv4+IPv6 by default, leave browsing as IPv4-only
  d) register and browse for services with both protos e) register
  IPv6-only, but browse both. f) Use only IPv6 as proto, but still
  register A RRs on it. g) Only use IPv6.

  Right now we have a), b), f), g), d). We still lack c), and e).

  Then, every few years or so we should move from one step to the next.
  We're right now at b), you guys jumped to d) without going through c)
  first. The code for c)/e) is missing right now. Instead of skipping it
  someone needs to sit down and just write it.

So please, for proper IPv6 support, fix the remaining issues first. And
then do it in a sane way instead of doing the third step without having
done the second.

I'll will fix this eventually, when I find the time to and the issue is
pressing enough. I am always happy to accept patches, if you guys want
to speed this up.

Also, let's not forget that there is not a single installation around
which uses exclusively IPv6 these days. All IPv6 installations are
multi-stack installations. Thus using IPv4 for link local service
discovery is absolutely fine.

Thanks,
	Lennart

-- System Information:
Debian Release: lenny/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.24-1-686 (SMP w/1 CPU core)
Locale: LANG=de_DE at euro, LC_CTYPE=de_DE at euro (charmap=ISO-8859-15)
Shell: /bin/sh linked to /bin/bash

Versions of packages avahi-daemon depends on:
ii  adduser                       3.107      add and remove users and groups
ii  bind9-host [host]             1:9.4.2-10 Version of 'host' bundled with BIN
ii  dbus                          1.2.1-1    simple interprocess messaging syst
ii  libavahi-common3              0.6.22-3   Avahi common library
ii  libavahi-core5                0.6.22-3   Avahi's embeddable mDNS/DNS-SD lib
ii  libc6                         2.7-10     GNU C Library: Shared libraries
ii  libcap1                       1:1.10-14  support for getting/setting POSIX.
ii  libdaemon0                    0.12-1     lightweight C library for daemons 
ii  libdbus-1-3                   1.2.1-1    simple interprocess messaging syst
ii  libexpat1                     1.95.8-4   XML parsing C library - runtime li
ii  lsb-base                      3.1-24     Linux Standard Base 3.1 init scrip

Versions of packages avahi-daemon recommends:
ii  libnss-mdns                   0.10-3     NSS module for Multicast DNS name 

-- no debconf information