Re: [PATCH 0/6] Deprecate Legacy IP

Bjoern A. Zeeb
2026-04-01T16:44:40Z

On 4/1/26 07:44, David Woodhouse wrote:

Hi David,

(fun fishing this out from nntp.lore.kernel.org needing NAT64)

> RFC1883, the IPv6 standard, was published in the final decade of the 1900s.
> That's closer in time to the Apollo 11 moon landing than it was to today.
>
> Even our esteemed Maddog has worked with computers for longer in the IPv6
> era, than he ever did before it.
>
> Yet Linux still can't even be *built* with only IPv6 support and without
> support for Legacy IP. This long overdue patch series fixes that, and
> ...

This is very interesting; I'll be happy to read the more serious
discussions for 6/6 this year then :)

That said, I've been there 15 years ago and done that for real,
just not for Linux:
https://freebsdfoundation.org/blog/freebsd-foundation-and-ixsystems-announce-ipv6-only-testing-versions-of-freebsd-and-pc-bsd/

A lot of parts (e.g., PC-BSD,the IPv6-only snapshots we published
back then, websites) are long gone, but FreeBSD today still has NO-INET
(as well as NO-INET6 and NO-IP) kernel configs which are regularly tested
as part of a universe build to make sure the status-quo stayed, along with
options to build (large parts) of userspace without IPv4 support.

I have since run real IPv6-only machines :]]
EAFNOSUPPORT and EPROTONOSUPPORT are (were) a good friend of mine.

It helped a lot back then to find applications which had real trouble
working without IPv4.
It was fun sitting in a UKNOF presentation years later to hear about
all these applications just working on IPv6-only and knowing why, whereas
the presenter was unaware, and still had a 127.1 on his loopback *sigh*

IPv6-only is something a lot of people will not understand and someone
just has to do it! It is a worthwhile goal, even if late, as you say.
My reminder to people these days is: DNSsec is even older than IPv6.

I have moved on (though would love to go back to more IPv6);
please feel free to get in touch in case you want me to go and swap in
some more memories from that time to share experience and help.

To the global deployment of IPv6!
/bz