linux-kernel - Re: mss to pmtu clamping partially broken?

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Message-ID: <Pine.LNX.4.64.0707022147540.25153@bizon.gios.gov.pl>
Date:	Mon, 2 Jul 2007 21:50:46 +0200 (CEST)
From:	Krzysztof Oledzki <ole@....pl>
To:	Phil Dibowitz <phil@...m.com>
cc:	Andreas Steinmetz <ast@...dv.de>,
	Jan Engelhardt <jengelh@...putergmbh.de>,
	netfilter-devel@...ts.netfilter.org,
	Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>
Subject: Re: mss to pmtu clamping partially broken?



On Mon, 2 Jul 2007, Phil Dibowitz wrote:

> On Mon, Jul 02, 2007 at 09:16:57PM +0200, Krzysztof Oledzki wrote:
>>
>>
>> On Mon, 2 Jul 2007, Phil Dibowitz wrote:
>>
>>> On Mon, Jul 02, 2007 at 07:04:12PM +0200, Andreas Steinmetz wrote:
>>>> Jan Engelhardt wrote:
>>>>> Do you really need clamping? It's a hack, since TCP should do MSS
>>>>> negotiation
>>>>> itself. (Of course it may happen that some routers are broken.) But
>>>>> usually not
>>>>> for incoming packets.
>>>>
>>>> You never know when you hit ICMP blackholes, broken routers and other
>>>> evil things. Better safe than sorry so clamping is the way to go for me.
>>>
>>> I encourage you to report PMTUD Blackholes to the MSS Initiative at
>>> http://www.phildev.net/mss/
>>
>> Any chances for similar initiative for "SACK vandals"? ;)
>
> There's already a counterpart for ECN blackholes, so I'm not opposed to it.
> However, keeping up with new reports, re-testing existing offenders, etc.
> takes up a good chunk of time, so I don't have the time to do it myself. I'm
> happy to reference such a site, however.

Indeed and it seems there are more important issues, like similar window 
scaling problem for example. :(

Best regards,

 				Krzysztof Olędzki