RE: Caching a sniffer

["Nero, Nick" <Nick.Nero () disney com>]

Great article covering about everything you can do on Layer2 . ..

http://www.cisco.com/en/US/netsol/ns340/ns394/ns171/ns128/networking_sol
utions_white_paper09186a008014870f.shtml 

-----Original Message-----
From: David Gillett [mailto:gillettdavid () fhda edu] 
Sent: Thursday, March 25, 2004 11:21 AM
To: 'Andrew Shore'
Cc: security-basics () securityfocus com
Subject: RE: Caching a sniffer

> A switch is not a hub/router. In fact it is a micro segmented bridge.
>
> A switch operates at layer 2 of the OSI model ie MAC address layer. 

  Amen, brother.
 
> Therefore if someone has plugged a scanner into a network point they 
> will not be able to sniff any useful information from the network 
> unless that person has admin access to the switch. You can check this 
> by ensuring that none of the ports on the switches are in span mode

  While you need admin access to set up a span port, Shawn and I have
alluded to two different techniques which can allow non-admin users to
sniff traffic on a switched network.  It's true that neither of these is
quite "normal behaviour" -- they involve using special tools to modify
the behaviour of hosts or switches.  But the tools exist and are readily
available, and so the issue that confronts admins is how to detect
and/or frustrate their use.

David Gillett




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