netdev - Re: [RFC PATCH net-next 0/7 v2]IPv6:netfilter: defragment

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Message-ID: <4B98B4FC.50904@cn.fujitsu.com>
Date:	Thu, 11 Mar 2010 17:16:44 +0800
From:	Shan Wei <shanwei@...fujitsu.com>
To:	YOSHIFUJI Hideaki <hideaki.yoshifuji@...il.com>
CC:	Patrick McHardy <kaber@...sh.net>,
	David Miller <davem@...emloft.net>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Yasuyuki KOZAKAI <yasuyuki.kozakai@...hiba.co.jp>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	netfilter-devel@...r.kernel.org,
	"yoshfuji@...ux-ipv6.org >> YOSHIFUJI Hideaki" 
	<yoshfuji@...ux-ipv6.org>
Subject: Re: [RFC PATCH net-next 0/7 v2]IPv6:netfilter: defragment

yoshifuji-san:

YOSHIFUJI Hideaki wrote, at 03/11/2010 01:13 AM:
> Well, because the context of defragment are different
> from standard ones (e.g., In netfilter, defragment can
> happen even on forwarding path, and the result is always
> thrown away anyway), I think it is not a good idea to
> touch standard MIB here. However I'm okay to increment
> other stats like InDiscards, OurDiscards and netfilter
> specific stats.

Not only on router, but also on host, if conntrack fails to reassemble
fragments, the fragments will not be forwarded to IPv4/IPv6 stack.
So, these fragments can't be traced from MIB counter.

And, IPv4 conntrack records these fragments.
Is the context of IPv4 defragment different from IPv6?

> On the other hand, I'd even say we should NOT send
> icmp here (at least by default) because standard routers
> never send such packet.

Yes，for routers, the patch-set does not send icmp message to
source host. It only does on destination host with IPv6 connection 
track enable.

-- 
Best Regards
-----
Shan Wei
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