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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20070702193541.GA14961@ipom.com>
Date:	Mon, 2 Jul 2007 12:35:41 -0700
From:	Phil Dibowitz <phil@...m.com>
To:	Krzysztof Oledzki <ole@....pl>
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, 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.

Though - I'm not familiar with the problem of SACK vandals either. There
appears to be a thread on here, I'll go read it...

-- 
Phil Dibowitz                             phil@...m.com
Open Source software and tech docs        Insanity Palace of Metallica
http://www.phildev.net/                   http://www.ipom.com/

"Never write it in C if you can do it in 'awk';
 Never do it in 'awk' if 'sed' can handle it;
 Never use 'sed' when 'tr' can do the job;
 Never invoke 'tr' when 'cat' is sufficient;
 Avoid using 'cat' whenever possible" -- Taylor's Laws of Programming


Download attachment "signature.asc" of type "application/pgp-signature" (190 bytes)