Re: Sniffing on a switch

From: Volker Tanger (vtlists@wyae.de)
Date: Sat Oct 29 2005 - 06:48:21 EDT


Greetings!

On Thu, 27 Oct 2005 19:55:04 -0700
"Andy Meyers" <andy.meyers@hushmail.com> wrote:

> Now i know people say you "cant" sniff on a switch and I know about
> ARP poisoning and MAC flooding. But there has to be another way. I
> have heard too many stories about "he sniffed my AIM conversation on a
> Cisco switch" (an example is in the most recent version of 2600). Does
> anyone know of any technique how to do this? Can you ARP poison a
> switch?

On many managable (enterprise) switches often have a sniffing/mirror
port where you can configure from which switch port(s) you want all
traffic to be mirrored to this mirror port.

And yes, all unprotected switches can be subjected to ARP poisoning. But
(again) many manageable switches can be configured with preventive
measures:

- static/manual MAC/port mapping

- automatic one-time MAC/port config: the very first MAC/port
  combination seen is taken as semi-static entry, all others are dropped.

- limiting number of MAC addresses per port allowed
  (which helps against rogue switches and router, too)

For all you need the help of the switch admins. So no help if you want
to guard yourself against "evil" switchmasters... ;-)

Bye

Volker

-- 
Volker Tanger    http://www.wyae.de/volker.tanger/
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