IPNAT seems to affect network performance? of jails on lo0 (10.0.0.0/24) - why?

[Kalle Møller]

I know that ssh does a reverse dns lookup of the ip you connect from -
no matter if its local or not.

On Tue, Jun 26, 2012 at 4:58 PM, Christopher J. Ruwe <cjr at cruwe.de> wrote:
> On Mon, 25 Jun 2012 18:23:56 -0400
> Robert Huff <roberthuff at rcn.com> wrote:
>
>>
>> Christopher J. Ruwe writes:
>>
>> >  On a KVM virtualized host, I run FreeBSD 8.3-RELEASE-p3 and some
>> >  qjails, 8.3-RELEASE. The jails are connected all via lo0 on
>> >  10.0.0.0.
>> >
>> >  While by the large working as expected, I have noticed one
>> >  pecularity I have failed to pinpoint: When launching processes
>> >  with some network interaction, like sshing into one of the jails
>> >  from the platform or launching emacs, the command spends ages (
>> >  ~(1-2) minutes) idling?  (nothing happens) before becoming
>> >  interactive.
>>
>>       If the number is very close to 90 seconds, my first guess
>> would be you have a DNS problem.
>>
>>
>>                                       Robert Huff
>>
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>
> Thanks for the hint. It was DNS ... I have copied a resolv.conf into the
> jails for future use, but did not enable NAT from the start.
>
> The issue disappeared when I commented out the nameserver entries and
> switched NAT off again, i.e., I could login using ssh in a matter of
> seconds, not minutes.
>
> Now to the followup: Why does ssh and emacs! require DNS for entirely local
> connections or just to be started?
>
> Anyway, thanks for that hint, cheers,
> --
> Christopher
> TZ: GMT + 2h



-- 

Med Venlig Hilsen

Kalle R. Møller