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From: jwlargent <jwlargent@vlsmaps.com>
To: NetFilter <netfilter@lists.netfilter.org>
Subject: Re: Shouldn't this rule catch all packets
Date: Thu, 14 Dec 2006 15:46:33 -0600	[thread overview]
Message-ID: <4581C639.5040208@vlsmaps.com> (raw)
In-Reply-To: <slrneo3b2o.8uu.xpisar@album.ics.muni.cz>

Petr Pisar wrote:
> On 2006-12-14, jwlargent <jwlargent@vlsmaps.com> wrote:
>   
>> I was trying to debug some errors in my iptables setup so I added the 
>> following rules to my OUTPUT, just to see what packets were going out.
>>
>> iptables -A OUTPUT -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
>> iptables -A OUTPUT -j ACCEPT
>>
>> When I do iptables -L OUTPUT -v it shows some packets are falling 
>> through to the last rule.
>> Shouldn't the first rule catch all the packets?
>>
>>     
> No. There exists forth state called INVALID. E.g. TCP packet with ACK
> witch is not part of any tracked TCP connection is INVALID. Naturally,
> INVALID packets are ill packets and they shoudn't appear, but the reality
> is different.
>
> -- Petr
>
>   
So I put in a log rule for --state INVALID and sure enough thats what it 
was.
The packets are part of my ssh connection, tcp with ACK.

IN= OUT=eth0 SRC=xxx.xxx.xxx.xxx DST=xxx.xxx.xxx.xxx LEN=276 TOS=0x10 
PREC=0x00 TTL=64 ID=1146 DF PROTO=TCP SPT=22 DPT=38858 WINDOW=3228 
RES=0x00 ACK PSH URGP=0



      reply	other threads:[~2006-12-14 21:46 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-12-14 19:16 Shouldn't this rule catch all packets jwlargent
2006-12-14 19:56 ` Petr Pisar
2006-12-14 21:46   ` jwlargent [this message]

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