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Date:      Fri, 18 May 2001 02:53:31 -0500
From:      Will Andrews <will@physics.purdue.edu>
To:        Ted Mittelstaedt <tedm@toybox.placo.com>
Cc:        Will Andrews <will@physics.purdue.edu>, questions@FreeBSD.ORG
Subject:   Re: Promiscuous mode?
Message-ID:  <20010518025331.S26877@casimir.physics.purdue.edu>
In-Reply-To: <005001c0df6c$56820f00$1401a8c0@tedm.placo.com>; from tedm@toybox.placo.com on Fri, May 18, 2001 at 12:29:56AM -0700
References:  <20010518012637.Q26877@casimir.physics.purdue.edu> <005001c0df6c$56820f00$1401a8c0@tedm.placo.com>

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On Fri, May 18, 2001 at 12:29:56AM -0700, Ted Mittelstaedt wrote:
> Under FreeBSD, programs like trafshow are "bpf clients" they
> use the bpf interface which puts the card in promiscious mode.

I know that.

> In your scheme, however, that hub that the DSL line is connected to
> and that the BSD box and the other computers are connected to,
> it MUST be a flat hub, NOT a switch.  Switches will normally
> prevent all the traffic from being seen.  As long as it's a hub
> you will be fine.

I also know that.  It is indeed a hub and not a switch.  :)

> the snmp daemon only looks at traffic that is directed to the
> computer, not at all traffic on the Ethernet.

Ouch.  That's not good.  Perhaps I'll have to try some other method of
getting the data octet counts.  If I do that at least I'll be able to
get rid of the SNMP daemon..  SNMP isn't granular enough anyway; I'd
prefer to graph the usage per IP address rather than per interface.
Perhaps I'm missing something, but anyway...

> BTW, what is the DSL CPE that your using to connect to the DSL line?
> Some of the CPE's have SNMP in them and can give you traffic stats
> that you can track with a program like MRTG.

I don't know what a "CPE" is, but the gateway my system is connected to
doesn't respond to SNMP requests.  :(

I forgot to mention that currently all traffic goes through one IP
address so I'm currently able to use mrtg to graph the usage through
net-snmp on localhost.  That's changing soon though, hence why I'm
asking about these things.  So I guess all I need is to figure out how
to get the octet counts on the external interface once the network
topology changes.

TIA,
-- 
wca

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