From: Pandu Poluan <pandu@poluan.info>
To: netfilter@vger.kernel.org
Subject: Re: Blocking UDP Fragments
Date: Thu, 19 May 2011 15:43:51 +0700 [thread overview]
Message-ID: <BANLkTinxquz70w+QXTDAk0FY5T5cwMNmWg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.01.1105181421340.2862@frira.zrqbmnf.qr>
On Wed, May 18, 2011 at 19:23, Jan Engelhardt <jengelh@medozas.de> wrote:
>
> On Wednesday 2011-05-18 06:27, Pandu Poluan wrote:
>>
>>If you want to drop all fragmented packets, including the first packet
>>of the fragment,
>>
>>iptables -t raw -A PREROUTING -m u32 ! --u32 0x4&0x3fff=0x0 -m comment
>>--comment \"Fragmented\" -j DROP
>
> Yeah but you forget
>
> iptables -f -j DROP
>
> and that, when nf_defrag is loaded, autodefragmentation is happening and
> Xtables won't see any more fragments.
>
Why should I match against -f ? Doesn't " ! --u32 0x4&0x3fff=0x0 "
already match against the first and subsequent packets?
And when does nf_defrag actually do its magic? Doesn't it take place
during conntrack, and thus after '-t raw' ?
Rgds,
--
Pandu E Poluan
~ IT Optimizer ~
Visit my Blog: http://pepoluan.posterous.com
next prev parent reply other threads:[~2011-05-19 8:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-16 20:42 Blocking UDP Fragments Ryan Gelobter
2011-05-18 4:27 ` Pandu Poluan
2011-05-18 12:23 ` Jan Engelhardt
2011-05-19 8:43 ` Pandu Poluan [this message]
2011-05-19 8:51 ` Pandu Poluan
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