[Pkg-exim4-users] dc_minimaldns not working?

[Marc Haber]

On Sat, Mar 15, 2008 at 09:51:49PM +0100, Lothar Ketterer wrote:
> On Sat, Mar 15, 2008 at 11:35:33AM +0100, Marc Haber wrote:
> > Interesting. I have installed etch r2 in a virtual machine, and see
> > the AAAA lookups as well. However, when I dpkg-reconfigure exim4 for
> > minimaldns, the AAAA lookups seem to vanish on my test system.
> 
> If this is only a problem on my box and not etch in general, it's ok
> then.

It doesn't seem to happen on all systems for sure, but it might be a
more general issue.

> > I would think that there should be a different loopback address for
> > IPv6 as well, but I don't know enough about IPv6, and for me, setting
> > minimaldns eliminates the lookups on exim startup
> 
> I looked into this today. For IPv4, RFC 3330 (Special-Use IPv4
> Addresses) [1] says:
> 
>   127.0.0.0/8 - This block is assigned for use as the Internet host
>   loopback address.
> 
> Regarding IPv6, RFC 4291 (IP Version 6 Addressing Architecture) [2]
> states
> 
>   Address type         Binary prefix        IPv6 notation   Section
>   ------------         -------------        -------------   -------
>   ...
>   Loopback             00...1  (128 bits)   ::1/128         2.5.3
>   ...
> 
> and in Section 2.5.3 (The Loopback Address):
> 
>   The unicast address 0:0:0:0:0:0:0:1 is called the loopback address.
> 
> Seems like IPv6 has only one loopback address.

I _think_ that the concept of loopback addresses can be filled in IPv6
with link local addresses on the local interface (lo on Linux).

> If you agree that the solution then is to append the hostname to the
> line beginning with "::1" in /etc/hosts, i wanted to suggest to include
> this in Section 1.3.7 of the FAQ, like this:
> 
>   Add an IPv6 record for your hostname (listed in /etc/hostname)
>   to /etc/hosts by creating a line that says
>     ::1             ip6-localhost ip6-loopback <your_hostname>
>   If there is already a line starting with "::1", append your hostname
>   to it. You can check with "getent hosts your_hostname" whether
>   this was successful.
> 
> What do you think about it?

I am not fully convinced how that needs to be solved with IPv6.

> > > Then why is an IPv6 entry for the hostname given during installation
> > > missing?
> > 
> > I guess because it hasn't been implemented yet.
> 
> But /etc/hosts contains IPv6 entries after installation? Looks like it
> is just the hostname that is missing.

Yes, but the 127.0.1.1 entry was implemented later in the development
cycle. Either the corresponding ipv6 entry was forgotten, or there is
a reason for it not being present.

I remember weird things happening while 127.0.0.1 was connected with
the host name years back.

Greetings
Marc

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