Subject: Re: DNAT sporadically doesn't replace destination IP address

From: "Kris Op de Beeck" <[email-masked]>
Date: Thu, 22 May 2008 17:34:20 +0200

>>> On 22/05/2008 at 17:28, in message <[email-masked]>, Patrick
McHardy <[email-masked]> wrote:
> Kris Op de Beeck wrote:
>> 
>>>>> On 22/05/2008 at 16:57, in message <[email-masked]>, Patrick
>> McHardy <[email-masked]> wrote:
>>> Please try loading ipt_LOG and executing
>>>
>>> "echo 255 >/proc/sys/net/netfilter/nf_conntrack_log_invalid"
>>>
>>> and see if something shows up in the ringbuffer.
>> 
>> [  917.584000] nf_ct_tcp: invalid SYNIN= OUT= SRC=192.168.1.23 DST=10.9.9.22 
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=3257 DF PROTO=TCP SPT=40018 DPT=80 
> SEQ=1136088214 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT 
> (020405B40402080A00025B1C0000000001030307) UID=1000
>> [  918.800000] nf_ct_tcp: invalid SYNIN= OUT= SRC=192.168.1.22 DST=10.9.9.21 
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=26411 DF PROTO=TCP SPT=47713 DPT=80 
> SEQ=1041054567 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT 
> (020405B40402080A00025C4C0000000001030307) UID=1000
>> [  921.800000] nf_ct_tcp: invalid SYNIN= OUT= SRC=192.168.1.22 DST=10.9.9.21 
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=26412 DF PROTO=TCP SPT=47713 DPT=80 
> SEQ=1041054567 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT 
> (020405B40402080A00025F3A0000000001030307) UID=1000
>> [  924.204000] nf_ct_tcp: invalid SYNIN= OUT= SRC=192.168.1.30 DST=10.9.9.29 
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=25744 DF PROTO=TCP SPT=52775 DPT=80 
> SEQ=2154890499 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT 
> (020405B40402080A000261930000000001030307) UID=1000
>> [  927.204000] nf_ct_tcp: invalid SYNIN= OUT= SRC=192.168.1.30 DST=10.9.9.29 
> LEN=60 TOS=0x00 PREC=0x00 TTL=64 ID=25745 DF PROTO=TCP SPT=52775 DPT=80 
> SEQ=2154890499 ACK=0 WINDOW=5840 RES=0x00 SYN URGP=0 OPT 
> (020405B40402080A000264810000000001030307) UID=1000
>> 
>> For those DST ip addresses I've got failures
> 
> Which kernel is this test running on? That message
> is gone since 2.6.22.

s3p@burnin:~$ uname -a
Linux burnin 2.6.22-14-generic #1 SMP Sun Oct 14 23:05:12 GMT 2007 i686 GNU/Linux

This was the config where I detected the problem. (Ubuntu 7.10)

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