[conspire] missing rDNS for (intentionally missing) IPv6

[Rick Moen]

Quoting Tim Utschig (tim at tetro.net):

> I'm interested to hear how this goes. I'm curious if they've
> improved...

OK, will advise.  I got a ticket number, and they're supposed to tag
back to me on my cellular 'phone.  No calls yet.

Given that I stressed for purposes of the ticket that all mail outbound
from my server to GMail was currently being perm-fail rejected, I'm
already considering their response time a little less than awesome.
Luckily, having switched off IPv6 in the server stack, it's no longer an
emergency at this end.

Re-capping the proto-history of today's bizarreness:  Folks may recall
that I was a happy Raw Bandwidth Communication (RBC) ADSLv1 customer,
until Mike Durkin, proprietor, gave me a heads-up that business
machinations at the FCC was forcing him to terminate that line of
business a/o Dec. 19, 2019.  RBC was slowly rolling out some ADSLv2
connectivity, but not in my area.

Owing to medical matters in Nov. 2019, I wasn't able to fully grapple
with the problem until about a week before shutoff.  David Paoli and Kim
Davalos were kind enough to help me (as I was freshly out of surgery) 
in stringing a new run of ethernet cable from my server to the house's 
_other_ uplink, Comcast Business Internet cable service.  

After testing the new cable, I yanked the old one, plugged in the new
cable, and then manually re-IPed the server from the root command line
(like, using /sbin/ip and such) to switch over from RBC's static IP 
to the new one from Comcast.  I also carefully grepped for everywhere 
the old IP was inside /etc/, so I wouldn't accidentally miss anything, 
and accordingly updated

/etc/hosts
/etc/network/interfaces
Apache httpd conffiles
MTA conffiles
logcheck local rules
a whole lot of authoritative DNS stuff, as it's a nameserver

Then, I just restarted Apache httpd and my MTA, double-checked
everything, and called it a day.

It did not occur to me to do anything to disable IPv6 systemwide,
because nothing in /etc/network/interfaces (or /etc/hosts) mapped any
IPv6 address to any network interface.  I mean, why would I?  There
would be an IPv4 mapping from eth2 to IPv4 address 96.95.217.99 created 
at boot time _because_ of the configuration to do that in 
/etc/network/interfaces ...

:r /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

# The loopback network interface
auto lo
iface lo inet loopback

# This is a list of hotpluggable network interfaces.
# They will be activated automatically by the hotplug subsystem.
mapping eth0
	script grep
	map eth0

# The primary network interface
allow-hotplug eth2
iface eth2 inet static
	address 96.95.217.99
	netmask 255.255.255.248
	network 96.95.217.96
	broadcast 96.95.217.103
	gateway 96.95.217.102
#	dns-nameservers 198.144.192.2 198.144.192.4 198.144.195.186
#	dns-nameservers 198.144.192.2 198.144.192.4
	dns-nameservers 75.75.75.75 75.75.75.76
	dns-search com


...and /etc/hosts:

:r /etc/hosts

127.0.0.1	localhost
#198.144.195.184 network
#198.144.195.185 gateway
96.95.217.99 linuxmafia.com enzo uncle-enzo.linuxmafia.com uncle-enzo 
#198.144.195.187 wap
198.144.195.188 water.linuxmafia.com #opensprinkler
#198.144.195.189 unused 
198.144.195.190 desamo airport.deirdre.org #801.11g honeybadger honeybadger5
#198.144.195.191 broadcast

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts


I was thus truly surprised (and still am) to find that my server
suddenly had an IPv6 address after the unplanned restart of yesterday --
because nothing in /etc/ even mentions that address.