[Users] Disable IPv6

[Slavko]

Dňa 31. júla 2022 17:33:10 UTC používateľ "Renaud (Ron) OLGIATI" <renaud at olgiati-in-paraguay.org> napísal:
>On Sun, 31 Jul 2022 14:09:35 +0000
>Marco <mo01 at posteo.de> wrote:
>
>> Disabling IPv6 is a bad idea.
>
>Why ?

Why not?

IPv6 is here, it is used and it works. As i stated early in this
thread, nowadays OS are able to properly work with IPv6 enabled
in IPv4 only environment. The most often problem which i can see is
only when DNS returns AAAA, but doesn't provides access via IPv6,
but that becomes less and less common (but i still have some AAAA
responses overriden on my recursive DNS servers).

Disable (explicit) IPv6 means, that one cannot use it, when network
become IPv6 latter. I meet this problem eg. on one of my servers
(in job). Many years ago, in time when IPv6 was new, i had to disable
its IPv6 support, because other LAN machines (Windows) had troubles
to connect to it (i do not remember exact details) and then i forget
about it, as all works as expected. Then, years latter, i need to setup
VPN client, which connects to IPv6 capable server (my too) and things
become wrong. It tooks some time until i realized, that problem is, that
VPN server is trying to setup IPv6 on client machine, which fails, as
it was disabled...

As reported by google (https://www.google.com/intl/en/ipv6/statistics.html),
one can see that IPv6 usage continuosly grows and here are countries,
where its usage is over 50 %. More and more services are IPv6 only, as
new hosters have troubles to get enough IPv4 addresses for customers
at reasonable price. Consider that my ISP provides one static IPv4
address at price of two small (cheap) VPS.

I use IPv6 for years (via 6in4 tunnel, as my ISP know "that nobody
uses IPv6"), mostly to get experiences with it. And IMO, most of
IPv6 problems comes, because people try to do networking without
know/understand the differences from IPv4 -- in other words, they
setup firewall/router eg. without allowing required ICMPv6 (NDP) to
flow, which kill IPv6 connection without visible (at first look) reason,
and then they blame IPv6 itself...

I agree, disabling IPv6 nowadays is bad idea, as in most of cases,
it doesn't solve problem, only hides it.

regards

Slavko