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Date:      Tue, 12 Jun 2001 16:18:49 -0400 (EDT)
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
Message-ID:  <20010612160917.V445-100000@cithaeron.argolis.org>
In-Reply-To: <F21iyhGvDpEDiOa7ddh000002a3@hotmail.com>

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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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