From: Florian Westphal <fw@strlen.de>
To: Jiri Pirko <jiri@resnulli.us>
Cc: netdev@vger.kernel.org, pablo@netfilter.org,
netfilter-devel@vger.kernel.org, yoshfuji@linux-ipv6.org,
kadlec@blackhole.kfki.hu, kaber@trash.net
Subject: Re: IPV6 nf defrag does not work
Date: Tue, 29 Oct 2013 12:56:17 +0100 [thread overview]
Message-ID: <20131029115617.GA16615@breakpoint.cc> (raw)
In-Reply-To: <20131029105208.GA18526@minipsycho.orion>
Jiri Pirko <jiri@resnulli.us> wrote:
> On the current net-next if you on HOSTA do:
> ip6tables -I INPUT -p icmpv6 -j DROP
> ip6tables -I INPUT -p icmpv6 -m icmp6 --icmpv6-type 128 -j ACCEPT
>
> and on HOSTB you do:
> ping6 HOSTA -s2000 (MTU is 1500)
>
> Only the first ICMP echo request will be passed through, the rest is not
> passed on HOSTA. This issue does not occur with smaller packets than MTU (where
> fragmentation does not happen).
>
> I'm trying to find out where the problem is.
Are you sure this is new behaviour? As far back as I can remember
it was always like this.
in ip6tables, the individual fragments are sent through the ruleset,
iow. you'll need to make use of '-m conntrack' to match the fragments
belonging to an existing connection.
I don't know why this is, and I don't like this either.
But this is how it was implemented, see
net/ipv6/netfilter/nf_defrag_ipv6_hooks.c, ipv6_defrag() ->
nf_ct_frag6_output()
next prev parent reply other threads:[~2013-10-29 11:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-29 10:52 IPV6 nf defrag does not work Jiri Pirko
2013-10-29 11:56 ` Florian Westphal [this message]
2013-10-29 12:03 ` Jiri Pirko
2013-10-29 14:30 ` Jiri Pirko
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