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Date:      Fri, 2 Jan 2009 23:44:08 -0600
From:      David Kelly <dkelly@hiwaay.net>
To:        =?ISO-8859-1?Q?Sd=E4vtaker?= <sdavtaker@gmail.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Tool for traffic measure?
Message-ID:  <D0CA6472-99CC-4FF5-A6C8-FFE589E8593F@hiwaay.net>
In-Reply-To: <c37d69f60901022121t4d0f8e5dyd43c1eac76478c18@mail.gmail.com>
References:  <c37d69f60901022121t4d0f8e5dyd43c1eac76478c18@mail.gmail.com>

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On Jan 2, 2009, at 11:21 PM, Sd=E4vtaker wrote:

> Hello,
> I got a subnet with 5 machines and a cablemodem who provides 5 =20
> public ips
> All is conected to a switch.
> One of the machines is not ours and we want to check it is not
> abuseing our internet link, so we want to know if there is any way to
> monitor bandwich usage from one of the other machines in the subnet
> with no need to modify the foreing machine config. Something like use
> tcpdump in promiscuos mode or something like that, we doesnt matter
> the content, we just need a bandwich conssumption meassure.
> Thanks for any ideas.

Buy a smarter switch and do the traffic counts in the switch.

As things stand the switch is isolating all 5 machines from each =20
other, none hear what the others have to say to the cable modem, so =20
there is no way you can sniff the other's traffic.

If instead of a switch you had a dumb hub then all machines would =20
hear what all the other machines were saying to each other and the =20
cable modem. Is very hard to buy a dumb hub these days. Is easier to =20
buy a smarter switch. A configurable smart switch can deliver the =20
questionable machine's traffic to both the cable modem and to one of =20
your machines but there is no point unless you want/need to see the =20
contents of the packets. A switch that smart should also be able to =20
count packets and tally total byte counts. If I understand correctly =20
that is all you want.

--
David Kelly N4HHE, dkelly@HiWAAY.net
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Whom computers would destroy, they must first drive mad.






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