Subject: Re: HEADS UP! Default value of ip6_v6only changed
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Bill Studenmund <>
List: tech-net
Date: 10/29/2003 22:54:14
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On Tue, Oct 28, 2003 at 06:38:50AM -0500, der Mouse wrote:
> > ok. so why this message in /usr/pkgsrc/www/MozillaFirebird-bin/MESSAGE?
> > $ more MESSAGE.NetBSD=20
> [...]
> >         Please note that if you have INET6 enabled in your kernel, you
> >         will need to set net.inet6.ip6.v6only=3D0, using sysctl(8).
> Since I'm not responsible for any of the Mozilla code, much less the
> networking code, I can only conjecture.  My guess would be that the
> author(s) was(were) lazy and, when v6 is available, insist on doing
> everything, even v4 connections, through v6 sockets, instead of using
> v4 sockets for v4 work and v6 sockets for v6 work - but couldn't be
> bothered to explicitly set V6ONLY to 0 on the sockets in question.

My understanding of this issue is that Mozilla does:

	[get DNS lookup info]
	[find v6 record first]
	s =3D socket(first-record-domain, SOCK_STREAM, 0);
	for ([itterate over DNS info]) {
		connect(nth DNS entry);
		if (succeeded)

The main thing is that they create either a v4 or v6 socket, then connect=
to v4 or v6 addresses with that socket. So they will open a v6 socket and=
try to connect to a v4 address if you have v6 enabled.

Thus the issues.

Take care,


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