From: Kristian Evensen <kristian.evensen@gmail.com>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: Wrong MAC in redirected packet
Date: Wed, 25 Mar 2009 20:56:10 +0100 [thread overview]
Message-ID: <49CA8C5A.1030908@gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.00.0903252047020.28681@fbirervta.pbzchgretzou.qr>
Jan Engelhardt skrev:
> On Wednesday 2009-03-25 20:47, Kristian Evensen wrote:
>
>> However, I have noticed a similar problem when using my module on incoming
>> packets in PREROUTING (on the multihomed receiver), the IP adress is changed
>> (accoring to my dmesg-output) but then they are not heard from again.
>>
>
> Probably dropped due to L3 or L4 checksum mismatches. While we try to
> change the checksum, I have not verified it for all cases.
>
>
Hm, I am noe sure. I recalculate the checksum (using csum_replace4 for
l3 and inet....replace4 for l4) after modifying the destination IP, and
when used with OUTPUT the checksum is correct. Since tcpdump/Wireshark
outputs the packets before they are modified I haven't been able to
verify this though.
-Kristian
next prev parent reply other threads:[~2009-03-25 19:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-25 14:27 Wrong MAC in redirected packet Kristian Evensen
2009-03-25 14:33 ` Jan Engelhardt
2009-03-25 15:00 ` Kristian Evensen
2009-03-25 15:04 ` Jan Engelhardt
2009-03-25 15:17 ` Kristian Evensen
2009-03-25 15:20 ` Jan Engelhardt
2009-03-25 19:47 ` Kristian Evensen
2009-03-25 19:48 ` Jan Engelhardt
2009-03-25 19:56 ` Kristian Evensen [this message]
2009-03-25 19:57 ` Jan Engelhardt
2009-03-25 21:00 ` Kristian Evensen
2009-03-26 10:26 ` Kristian Evensen
2009-03-26 20:07 ` Jan Engelhardt
2009-03-26 20:54 ` Kristian Evensen
2009-04-26 9:46 ` Jan Engelhardt
2009-04-26 16:22 ` Kristian Evensen
2009-04-26 21:29 ` Jan Engelhardt
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