[ejabberd] prefer IPv6 for outgoing s2s connections

Jeff McAdams jeffm at iglou.com
Mon Dec 10 21:07:56 MSK 2007


Andreas wrote:
> 
> On Mon, 10 Dec 2007 09:36:40 -0500, Sean Dilda <sean at duke.edu> wrote:
>>> This topic is not described in the ejabberd guide. Looking at the
>>> source code that establishes an outgoing S2S connection [1], ejabberd
>>> first tries using IPv4. In case of error it tries with IPv6.
>>>
>> Seems like that logic should be reversed.

> I disagree. I think this policy makes perfect sense in a world with so much
> IPv4 and so little IPv6 use. It would only slow things down. Eg. when you
> read a guide on speeding up Firefox, one of the things mentioned is
> *disabling* IPv6...

> On a more serious note, quite some IPv6 security flaws have been reported,
> and some people advise to simply disable IPv6 entirely (eg. I read this
> with regard to OpenBSD).

> So as a summary, if 99% uses IPv4, it makes perfect sense to try IPv4
> first. Hopefully IPv6 will get more widespread, though...

If all you care about is performance, and are willing to sacrifice
future-proofing your app for the benefit of gaining a couple of seconds
on initial connections in a few corner cases.

Preferring IPv4 over IPv6 is just flat-out wrong and is a bug that needs
to be fixed.
-- 
Jeff McAdams
"They that can give up essential liberty to obtain a
little temporary safety deserve neither liberty nor safety."
                                       -- Benjamin Franklin

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