netdev - Re: NAT stops forwarding ACKs after PMTU discovery

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Message-ID: <20130819143509.GA31320@linuxace.com>
Date:	Mon, 19 Aug 2013 07:35:09 -0700
From:	Phil Oester <kernel@...uxace.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Christoph Paasch <christoph.paasch@...ouvain.be>,
	Corey Hickey <bugfood-ml@...ooh.org>,
	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
	Linux Netdev List <netdev@...r.kernel.org>,
	netfilter-devel@...r.kernel.org
Subject: Re: NAT stops forwarding ACKs after PMTU discovery

On Mon, Aug 19, 2013 at 06:58:05AM -0700, Eric Dumazet wrote:
> Yeah, but here, this is conntrack who is blocking the thing.
> 
> TCP receiver has no chance to 'fix' it.
> 
> See conntrack is one of those buggy middle box as well.
> 
> So if you want to properly handle this mess, you'll also have to fix
> conntrack.

Better to fix the box which is randomizing the acks and ignoring
the SACKs.  Usually these are older Cisco PIX/ASA devices which just
need a code upgrade.  

Phil
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