Re: how do I disable IPv6?

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Tue, 27 Feb 2018 20:20:16 -0700
    From:        Andy Ruhl <acruhl%gmail.com@localhost>
    Message-ID:  <CAJcb3friwjn1nqvtjkzehpL1xCSf9mLnhZSd1iMiooSQDeki6A%mail.gmail.com@localhost>

  | There is DAD which shouldn't happen (but humans can cause it quite
  | easily which should be easy to test),

Do you mean DAD (which is the protocol that tests for duplicate
addresses), or duplicate addresses?   I suspect the latter.

  | and then there is DAD for a link
  | local address which *really* shouldn't happen.

Assuming the 2nd meaning, then that's true of EUI-64 generated
addresses, whatever scope they have.  But it is just as easy (or
at least almost as easy) to manually assign a link local address as
any other, and those are just as likely to be duplicates as any other.

  | Although I've heard
  | stories of duplicate MAC addresses from unscrupulous vendors before.

I have heard those stories as well, though never actually seen it,
and I am not sure I have ever actually talked to anyone who had
personally seen it either.

  | If DAD for the link local address works for one adapter and not
  | another, hopefully that would ring some bells for someone familiar
  | with that code. If not, get debug info.

If there is some hardware or driver that cannot do DAD correctly
(or just does not) then yes, that would be a bug worth fixing (if it
is the hardware, then unless there's an easy workaround, that
hardware would be worthless, and need replacing - just like a
(rotating metal) disc that refuses to spin...)

  | With respect, this isn't the only bug that causes annoying messages.

No, but DAD is not a bug, and the messages it produces when
it detects a duplicate are not "annoying" they are important.

That other systems can still see the duplicate addr, and generate
their own messages when they fail to work is I think a bug (the
ntpd errors in the message seemed to have that cause) and that
one should be fixed.

If we are still having issues with daemons (or clients) attempting
to use a tentative addr, while DAD is still proceeding, and failing in
an annoying way, that is also a bug, and should be fixed.

kre

ps: none of this has anything to do with port-amd64, it should be
moved to tech-net.   If anyone replies, please delete port-amd64