From: Patrick McHardy <kaber@trash.net>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 5/5] netfilter: xt_TEE: have cloned packet travel through Xtables too
Date: Thu, 01 Apr 2010 13:09:30 +0200 [thread overview]
Message-ID: <4BB47EEA.4020809@trash.net> (raw)
In-Reply-To: <alpine.LSU.2.01.1004011258060.17429@obet.zrqbmnf.qr>
Jan Engelhardt wrote:
> On Thursday 2010-04-01 12:37, Patrick McHardy wrote:
>
>> Jan Engelhardt wrote:
>>> Since Xtables is now reentrant/nestable, the cloned packet can also go
>>> through Xtables and be subject to rules itself.
>> That sounds dangerous if conntrack isn't used to prevent loops.
>
> Conntrack loops are prevented by using a dummy conntrack, just as
> NOTRACK does.
My question was about the case without conntrack.
>> Is that really useful? For filtering, you can simply apply the
>> rules before deciding to TEE the packet.
>
> I can think of a handful of applications:
> - CLASSIFY
Good point, you should probably reset a couple of skb members
after the skb_copy().
> - When the cloned packets gets XFRMed or tunneled, its status switches
> from "special" to "plain". Doing policy routing on them does not seem
> so far-fetched.
Fair enough, provided we can also handle loops when conntrack
isn't used.
next prev parent reply other threads:[~2010-04-01 11:09 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-31 10:38 nf-next: TEE and nesting Jan Engelhardt
2010-03-31 10:38 ` [PATCH 1/5] netfilter: ipv6: move POSTROUTING invocation before fragmentation Jan Engelhardt
2010-04-01 10:23 ` Patrick McHardy
2010-03-31 10:38 ` [PATCH 2/5] net: ipv6: add IPSKB_REROUTED exclusion to NF_HOOK/POSTROUTING invocation Jan Engelhardt
2010-04-01 8:34 ` David Miller
2010-03-31 10:38 ` [PATCH 3/5] netfilter: xtables: inclusion of xt_TEE Jan Engelhardt
2010-04-01 10:34 ` Patrick McHardy
2010-04-01 11:39 ` Jan Engelhardt
2010-04-01 11:54 ` Patrick McHardy
2010-03-31 10:38 ` [PATCH 4/5] netfilter: xtables2: make ip_tables reentrant Jan Engelhardt
2010-03-31 10:38 ` [PATCH 5/5] netfilter: xt_TEE: have cloned packet travel through Xtables too Jan Engelhardt
2010-04-01 10:37 ` Patrick McHardy
2010-04-01 11:03 ` Jan Engelhardt
2010-04-01 11:09 ` Patrick McHardy [this message]
2010-04-01 13:15 ` Jan Engelhardt
2010-04-01 13:22 ` Patrick McHardy
2010-04-01 13:44 ` Jan Engelhardt
2010-04-01 13:48 ` Patrick McHardy
2010-04-01 13:59 ` Jan Engelhardt
2010-04-01 14:03 ` Patrick McHardy
2010-04-02 18:15 ` Jan Engelhardt
2010-04-06 16:14 ` Jan Engelhardt
2010-04-06 16:37 ` Patrick McHardy
2010-04-07 13:26 ` Jan Engelhardt
-- strict thread matches above, loose matches on Subject: below --
2010-03-31 10:31 nf-next: TEE and nesting Jan Engelhardt
2010-03-31 10:31 ` [PATCH 5/5] netfilter: xt_TEE: have cloned packet travel through Xtables too Jan Engelhardt
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