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Date:      Tue, 12 Jun 2001 15:33:51 -0500
From:      "Derek O'Flynn" <derekoflynn@hotmail.com>
To:        piechota@argolis.org
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: snort/tcpdump not showing tcp packets
Message-ID:  <F184OlnzGOnXPJFcUFa00006a6b@hotmail.com>

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Marc,

Same type of NIC in both machines, 3com 3c595 fast etherlink III PCI
Both connected to a 10bT 3com hub.

It might be something with the card.  I have some isa nic cards I can try, 
and my new token ring card just arrived, but of course, I have to rebuild 
the kernel to add token ring support :(

Derek



>From: Matt Piechota <piechota@argolis.org>
>To: "Derek O'Flynn" <derekoflynn@hotmail.com>
>CC: <freebsd-security@FreeBSD.ORG>
>Subject: Re: snort/tcpdump not showing tcp packets
>Date: Tue, 12 Jun 2001 16:18:49 -0400 (EDT)
>
>On Tue, 12 Jun 2001, Derek O'Flynn wrote:
>
> > I have two machines, one running freebsd 4.0, and one running 4.3. They 
>are
> > physically connected to the same hub (same segment)
> >
> > When running tcpdump or snort on the 4.0 box, I get traffic from a 
>variety
> > of protocols
> >
> > However, when I run tcpdump or snort on the 4.0 box, I get traffic from 
>a
> > variety of protocols, but no tcp protocol traffic.  The only time tcp
> > protocol shows up is if I connect to the web server on the 4.3 box from
> > another machine.
>
>I assume you meant the 4.3 box in the above paragraph?
>
> > Strangest thing I've ever seen!  Anyway, I thought it might have been 
>cause
> > I did a minimal installation, and maybe something was disabled, so I 
>setup
> > the box again with a full install of everything but X, and the same 
>thing is
> > occurring.  I then thought it was the network card, but that can't be 
>cause
> > it is receiving tcp packets, but only those destined for the machine,
> > nothing else on the segment.  Is there a setting that causes it to only 
>see
> > it's tcp packets (note: it is seeing icmp/udp/arp packets from other
> > sources)
> >
> > Does anyone know if there's something weird with 4.3 that would cause 
>this?
> > I'm running the 4.3 iso image downloaded from freebsd.  It hasn't been
> > modified at all, standard installation.
>
>I'm running the same release as a dedicated sniffer device on a PC (Intel
>EEPro 100B NIC), and an IBM Stinkpad w/#com 3c574-TX NIC.  It works
>perfectly (as far as I can tell).  Could this be a problem with your
>specific card/driver and it's interaction with the TCPIP stack?
>
>--
>Matt Piechota
>Finger piechota@emailempire.com for PGP key
>AOL IM: cithaeron
>

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