From: Francois Romieu <romieu@fr.zoreil.com>
To: Jan Engelhardt <jengelh@medozas.de>
Cc: David Miller <davem@davemloft.net>,
cooldavid@cooldavid.org, netdev@vger.kernel.org
Subject: Re: jme: UDP checksum error, and lots of them
Date: Sat, 4 Dec 2010 00:02:50 +0100 [thread overview]
Message-ID: <20101203230250.GA3612@electric-eye.fr.zoreil.com> (raw)
In-Reply-To: <alpine.LNX.2.01.1012030044440.22334@obet.zrqbmnf.qr>
Jan Engelhardt <jengelh@medozas.de> :
> On Friday 2010-12-03 00:15, Francois Romieu wrote:
> >David Miller <davem@davemloft.net> :
> >[...]
> >> Something isn't right here. The only thing that makes sense is if
> >> the tcpdump checksum validation is wrong for some reason. Because
> >> only then could we give a reason for the UDP frames to not be
> >> dropped before vpnc can see them.
> >
> >Wild guess : 192.168... is the local address and tcpdump chokes on
> >an outgoing, yet-not-checksummed packet.
>
> Then the checksums of all other packets I am emitting would also be 0000
> or wrong, which isn't the case.
No. :o)
net/ipv4/udp.c::udp4_hwcsum_outgoing provides a packet data length
dependent partial checksum and it checksums fragments.
--
Ueimor
prev parent reply other threads:[~2010-12-03 23:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-02 3:39 jme: UDP checksum error, and lots of them Jan Engelhardt
2010-12-02 3:53 ` Guo-Fu Tseng
2010-12-02 4:09 ` David Miller
2010-12-02 4:33 ` Guo-Fu Tseng
2010-12-02 5:59 ` David Miller
2010-12-02 23:15 ` Francois Romieu
2010-12-02 23:54 ` Jan Engelhardt
2010-12-03 23:02 ` Francois Romieu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20101203230250.GA3612@electric-eye.fr.zoreil.com \
--to=romieu@fr.zoreil.com \
--cc=cooldavid@cooldavid.org \
--cc=davem@davemloft.net \
--cc=jengelh@medozas.de \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).