netdev - Re: [PATCH 1/1] netfilter: Add possibility to turn off netfilters defrag per netns

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Date:	Wed, 4 Jan 2012 09:49:53 +0100
From:	Hans Schillstrom <hans.schillstrom@...csson.com>
To:	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
CC:	Patrick McHardy <kaber@...sh.net>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	"jengelh@...ozas.de" <jengelh@...ozas.de>,
	"netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"hans@...illstrom.com" <hans@...illstrom.com>
Subject: Re: [PATCH 1/1] netfilter: Add possibility to turn off netfilters defrag per netns

Hello Jozsef

On Wednesday 04 January 2012 09:28:05 Jozsef Kadlecsik wrote:
> Hi Hans,
> 
> On Wed, 4 Jan 2012, Hans Schillstrom wrote:
> 
> > In some cases it not desirable to have auto defrag.
> > Ex. in a cluster where packets can arrive on different blades.
> > In that case it is possible to use containers (LXC) and send
> > all fragments to one place where defrag is enabled.
> > 
> > This patch makes it possible to turn off the defrag per network name space,
> > by setting net.netfilter.nf_conntrack_nodefrag to 1.
> > Both IPv4 and IPv6 is effected by this sysctl.
> > Default is 0 which is defrag.
> 
> Conntrack assumes that the packets are defragmented and will drop any 
> unfragmented one. So your patch results packet drops.

Hmmm, more work...
> 
> Also, if you want to disable defragmentation then why don't you simply 
> "mark" the packets with the NOTRACK target?

I don't think that will work since NF_IP_PRI_CONNTRACK_DEFRAG is -400

> 
> Best regards,
> Jozsef
>  

-- 
Regards
Hans Schillstrom <hans.schillstrom@...csson.com>
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