From: Phil Oester <kernel@linuxace.com>
To: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Cc: netfilter-devel@vger.kernel.org,
Pablo Neira Ayuso <pablo@netfilter.org>,
Corey Hickey <bugfood-ml@fatooh.org>
Subject: Re: [PATCH 1/1] netfilter: Ignore bogus SACK option values in TCP conntrack
Date: Mon, 2 Sep 2013 14:57:36 -0700 [thread overview]
Message-ID: <20130902215736.GA11580@linuxace.com> (raw)
In-Reply-To: <1378148280-1153-2-git-send-email-kadlec@blackhole.kfki.hu>
On Mon, Sep 02, 2013 at 08:58:00PM +0200, Jozsef Kadlecsik wrote:
> The netfilter TCP conntrack used to mark packets with bogus SACK option
> values as INVALID. However, it seems broken SEQ anonymizers, which are
> responsible for such traffic, are not going to die out soon and conntrack
> effectively blocks traffic coming through such devices.
>
> Better be liberal at conntrack level: when SACK is bogus, ignore it.
But if conntrack were being "liberal" then it wouldn't care about the value of
the ACKs either, no? This sort of defeats the purpose of TCP window tracking.
At the very least, this workaround should be dependent upon
nf_conntrack_tcp_be_liberal != 0.
Also note that David Miller refused to accept a patch working around this
issue in the TCP stack [1]. Why should netfilter do so?
Phil
[1] http://marc.info/?l=linux-netdev&m=137714232805063&w=2
next prev parent reply other threads:[~2013-09-02 21:58 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-02 18:57 [PATCH 0/1] netfilter: Ignore bogus SACK option values in TCP conntrack Jozsef Kadlecsik
2013-09-02 18:58 ` [PATCH 1/1] " Jozsef Kadlecsik
2013-09-02 20:39 ` Corey Hickey
2013-09-02 21:57 ` Phil Oester [this message]
2013-09-03 7:31 ` Jozsef Kadlecsik
2013-09-04 16:54 ` Phil Oester
2013-09-13 20:16 ` Jozsef Kadlecsik
2013-09-15 16:22 ` Phil Oester
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