> From: Matthias Scheler <[EMAIL PROTECTED]>
> On Wed, Jul 23, 2003 at 01:48:08PM +0200, Egbert Eich wrote:
> >  > I wasn't suggesting to use it on Linux. My suggestion was to revert to
> >  > using a single socket on all platforms and use the above code to enable
> >  > accepting IPv4 connections on *BSD.
> > Yes, I understand. I was just looking for a decend way of making
> > things work on Linux.
> 
> Using a single socket should work on Linux according to your observations.
> And it definitely works on Solaris. So adding some conditional code which
> uses setsockopt() with IPV6_V6ONLY on platforms which have IPV6_V6ONLY
> defined should work arround the platform.

The danger is that on systems where V4-mapped addresses are disabled an
attacker might just manage to bind to either the V6 socket, or the V4
socket and possibly execute a MitM attack.

> But we would get complaints from the IPv6 folks which consider accepting
> IPv4 connections on IPv6 listeners a problem. See here:
> 
> http://www.ietf.org/internet-drafts/draft-itojun-v6ops-v4mapped-harmful-01.txt
> 
> So we probably need to implement heuristics similar to the one described
> by Andrew Aitchison.

The issues that the draft brings up are irrelevant to XFree86. They are
strictly OS/firewall issues. If those problems can occur on a system, the
system is already swiss cheese; and nothing XFree86 can do will
alleviate things.

The draft was sent to BugTraq, and everyone who responded brought the
exact same issue up:

http://www.securityfocus.com/archive/1/289420/2002-08-20/2002-08-26/2
http://www.securityfocus.com/archive/1/289409/2002-08-20/2002-08-26/2
http://www.securityfocus.com/archive/1/289375/2002-08-20/2002-08-26/2
http://www.securityfocus.com/archive/1/289364/2002-08-20/2002-08-26/2

If you want to see both sides and the rest of the thread:
http://www.securityfocus.com/archive/1/288622/2002-08-20/2002-08-26/1


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