From: "John A. Sullivan III" <john.sullivan@nexusmgmt.com>
To: Jay Levitt <lists-netfilter@shopwatch.org>
Cc: netfilter@lists.netfilter.org
Subject: Re: Interaction of Ethereal and iptables?
Date: Mon, 12 Apr 2004 07:55:58 -0400 [thread overview]
Message-ID: <1081770958.16832.3.camel@localhost> (raw)
In-Reply-To: <065601c41f87$34f209e0$9701a8c0@office>
On Sun, 2004-04-11 at 01:38, Jay Levitt wrote:
> I'm occasionally seeing lines like the following, always to the same
> machine which is on my internal network:
>
> Apr 11 01:11:52 linux kernel: Rejected output by default:IN= OUT=eth0
> SRC=192.168.1.150 DST=192.168.1.151 LEN=40 TOS=0x00 PREC=0x00 TTL=64
> ID=30662 DF PROTO=TCP SPT=993 DPT=3736 WINDOW=6432 RES=0x00 ACK FIN
> URGP=0
>
> This corresponds to a LOG and then a DROP rule. So I set up Ethereal
> to capture the packet trace. I didn't see the packet there, so I
> changed the DROP to an ACCEPT, assuming that iptables is probably
> dropping the outbound packet before Ethereal (ok, libpcap) can see
> it.
>
> The weird thing is - even with just a LOG/ACCEPT rule, the packet is
> STILL missing from Ethereal's trace! All other packets from that time
> frame are there, but this particular one isn't. Could iptables be
> imagining it somehow? I'm using libpcap 0.7.2, which was current till
> a few days ago... I've done an iptables --list OUTPUT and verified
> that the last item on the OUTPUT chain is an ACCEPT of all packets,
> although the default policy is still technically DROP.
<snip>
Is there any chance it is being dropped by some other rule before it
hits the accept rule? If you add a log rule just in front of the ACCEPT
rule, is the packet still logged?
--
John A. Sullivan III
Chief Technology Officer
Nexus Management
+1 207-985-7880
john.sullivan@nexusmgmt.com
---
If you are interested in helping to develop a GPL enterprise class
VPN/Firewall/Security device management console, please visit
http://iscs.sourceforge.net
next prev parent reply other threads:[~2004-04-12 11:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-11 5:38 Interaction of Ethereal and iptables? Jay Levitt
2004-04-12 11:55 ` John A. Sullivan III [this message]
2004-04-12 12:46 ` Unknown, Alistair Tonner
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