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Re: defaulting to net.ipv6.bindv6only=1 for squeeze

#include <hallo.h>
* Marco d'Itri [Fri, Dec 11 2009, 12:23:36AM]:
> On Dec 10, Wouter Verhelst <wouter@debian.org> wrote:
> > Can you explain (or give pointers to an explanation) what the
> > argumentation here is? How does not adhering to relevant standards
> > simplify configuration?
> There is no relevant standard that says what the default of IPV6_V6ONLY
> should be. Currently what happens is that every OS except Linux and OS X
> default to 1.
> An important point is that the kfreebsd ports only support a default of
> 1, so these buggy programs need to be fixed anyway to work correctly on
> them.

From my POV as programmer it's a good change. The old behaviour (i.e.
silent creation of v4 mapped sockets) maybe made the porting (to
Linux/OS-X) of very simple network daemons easier but when you tried to
make the local address binding more flexible then things became PITA.

I.e. if you use getaddrinfo output then you need to sort out v6 sockets
out and connect on them, but then you cannot be sure about whether v4
mapping is active. You can test it by trial-and-error (binding on v4
versions and checking the results) but then you cannot be sure that they
are bound to you now (at least not without using ugly tricks).

> I have no objections to reverting this change in time for the release if
> there are too many programs to be fixed, but so far I believe that the
> results are very encouraging.

Maybe because most programmes already got burned by the problems
described above and don't rely on transparent v4 mapping anymore (IIRC I
had to fix some code last year when getaddrinfo output changed the
sort order, some assumptions in the code didn't work).


<natoka> Alfie: ;) naja, wir sind nicht in Redm**** wo man den teppich
	hochhebt und den besen auspackt und alles drunterkehrt.
<natoka> Alfie: und das was sich dann nicht mehr unterm teppich ausgeht als
	produkt deklariert und verkauft ;)

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