On Tue, 2013-01-08 at 10:09:20 -0800, Gregory Shapiro wrote:
> > How can I unstupid sendmail here?
>
> I don't think sendmail is being stupid here as it is doing what it has been
> doing under 8.x and 9.1 (the code is the same). I think something changed
> with the upgrade to 9.1. As far as tracking it down, the sendmail code does:
>
> getipnodebyname("acme.spoerlein.net", AF_INET6, AI_DEFAULT|AI_ALL, &err);
>
> This will only return an IPv4 mapped address if:
>
> 1. There are no IPv6 addresses configured on the interfaces. How are your
> IPv6 addresses assigned? If auto-configured (DHCPv6, RTADV), is it possible
> sendmail is being started before autoconfiguration has completed? Restarting
> the MTA after boot and seeing if it still gets the mapped address will say
> whether or not this is the cause.
>
> 2. The query for an AAAA record for acme.spoerlein.net failed. This doesn't
> appear to be the case for dns based on your dig output (assuming you ran that
> dig command on the same machine that is exhibiting the problem). However,
> your nsswitch.conf lists hosts before dns and there have been broken name
> resolution implementations that, with 'hosts' listed first in nsswitch.conf
> have given back bad info if the first hostname match didn't have the IPv6
> address. You could try switching the order in /etc/hosts to see if this
> helps. (Note, the broken implementation was not FreeBSD.)
>
> You can also test theory #2 by writing a small C program to do the
> getipnodebyname() call shown above and see what you get. If it gives the
> same bad address, then you need to look outside of sendmail. In the mean
> time, although not optimal, you can work around the issue by using the IPv6
> address instead of the hostname in the Addr= equate.
Turns out it was the missing setting of ip6addrctl_policy="ipv6_prefer"
in rc.conf that also bit me in strange and mysterious ways on another
machine where I did the upgrade. It's very unfortunate that this will
runtime-break sendmail and I honestly don't know why we make ipv4 the
default in this day and age.
Can some IPv6 guru chime in here? This is all thoroughly confusing.
Thanks!
Uli
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