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Date: Sun, 30 Sep 2012 23:25:59 +0200
From: Giuliano Pochini <pochini@shiny.it>
To: Alexey Vlasov <renton@renton.name>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Instead of IP addresses the kernel started to show zero's
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On Tue, 25 Sep 2012 14:26:07 +0400
Alexey Vlasov <renton@renton.name> wrote:

> Hi.
> 
> Here it writes LOG target from syslog:
> 
> Sep 25 03:23:49 l24 kernel: ip:SYN-OUTPUT-HTTP IN= OUT=eth0
> SRC=0000000000000000 DST=0000000000000000 LEN=60 TOS=0x00 PREC=0x00
> TTL=64 ID=22467 DF PROTO=TCP SPT=52829 DPT=80 WINDOW=14600 RES=0x00 SYN
> URGP=0 UID=564373 GID=155
> 
> This is recent, here go zero's again:
> # cat /proc/net/xt_recent/ssh-brute
> ...
> src=0000000000000000 ttl: 122 last_seen: 4371027622 oldest_pkt: 1
> 4371027622
>
> Can it be fixed without restarting the box?
> Thanks!
>
> Kernel 3.4.6.

It look similar to a problem that occurred on some 3.x heavy loaded
machines. After a while they begin to send packets with dst=0.0.0.0. We had
to revert to 2.6 on our production machines.

tcpdump output looks like this:

17:06:29.272225 IP 0.0.0.0.http > 0.0.0.0.1687: . ack 232 win 15400
17:06:29.272671 IP 0.0.0.0.http > 0.0.0.0.1687: P 0:511(511) ack 232 win 15400
17:06:29.272689 IP 0.0.0.0.http > 0.0.0.0.1687: F 511:511(0) ack 232 win 15400
17:06:29.273249 IP 0.0.0.0.http > 0.0.0.0.65307: . ack 62552748 win 1006 <nop,nop,timestamp 1760963 478909562>
17:06:29.273662 IP 0.0.0.0.http > 0.0.0.0.65307: P 0:511(511) ack 1 win 1006 <nop,nop,timestamp 1760963 478909562>
17:06:29.273678 IP 0.0.0.0.http > 0.0.0.0.65307: F 511:511(0) ack 1 win 1006 <nop,nop,timestamp 1760963 478909562>
17:06:29.278683 IP 0.0.0.0.http > 0.0.0.0.12021: . ack 1 win 12240
17:06:29.288707 IP 0.0.0.0.http > 0.0.0.0.28308: . ack 1049058319 win 12420
17:06:29.289406 IP 0.0.0.0.http > 0.0.0.0.28308: . ack 57 win 12420
17:06:29.289834 IP 0.0.0.0.http > 0.0.0.0.28308: P 0:487(487) ack 57 win 12420
17:06:29.289851 IP 0.0.0.0.http > 0.0.0.0.28308: F 487:487(0) ack 57 win 12420
17:06:29.291767 IP 0.0.0.0.http > 0.0.0.0.11407: P 0:472(472) ack 171 win 1275 <nop,nop,timestamp 1760982 2400635630>
17:06:29.292657 IP 0.0.0.0.http > 0.0.0.0.50511: . ack 1 win 14400
17:06:29.293502 IP 0.0.0.0.http > 0.0.0.0.12381: . ack 558 win 14960
17:06:29.295080 IP 0.0.0.0.http > 0.0.0.0.10980: . ack 2 win 16692

When the network traffic slows down the machine recovers to normal operation.

I found another report about this issue:

https://bbs.archlinux.org/viewtopic.php?id=129304


-- 
Giuliano.