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Re: sniffers
From: jmb () kryten Atinc COM (Jonathan M. Bresler)
Date: Sat, 29 Apr 1995 23:29:52 -0400 (EDT)

On Sat, 29 Apr 1995, Theodore Alexopoulos wrote:

Is there any way to find out if a sniffer is on the net?
Just this

        no.  absolutely none (per SANS'95 conference)

        a sniffer can have its transmit lead cut and still function.  
this configuration is described in one of the common security 
papers--TAMU's tiger paper perhaps, i dont remember.  with the transmit 
lead cut, you cant detect.

        now a good capture digital ocilloscope and a one shot pulse 
generator may allow you to see the reflections at each tap (imperfect 
impedence matching of coax and taps procudce reflections)  the time from 
pulse to reflection is twice the travel time to the tap.  a TDR (time 
domain reflectometer) does this.  but the signal will be very weak.  no 
standard network administrator equipment ;(


Jonathan M. Bresler  jmb () kryten atinc com    | Analysis & Technology, Inc.  
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play go.                                        | Arlington, VA 22202
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