Path: utzoo!mnetor!uunet!husc6!bloom-beacon!bu-cs!kwe
From: kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England))
Newsgroups: comp.dcom.lans
Subject: Re: Spoofing an ethernet device
Message-ID: <20822@bu-cs.BU.EDU>
Date: 22 Mar 88 17:48:11 GMT
References: <3071@dcatla.UUCP>
Reply-To: kwe@buit13.bu.edu (Kent England)
Followup-To: comp.dcom.lans
Organization: Boston Univ. Information Tech. Dept.
Lines: 24

In article <3071@dcatla.UUCP> dnwcv@dcatla.UUCP (William C. VerSteeg) writes:
>
>So, I wonder, why do I need the ethernet segment and 
>two transceivers ? I could use a low cost LNI, but even that has capabilities 
>that I don't REALLY need. Is there a way to cable the output of the first 
>device to the input of the second device such that no active components 
>are needed? 

	This is the famous request for a null transceiver cable.  In
answer to your question, as with a null RS-232 cable there are certain
signals that can't be duplicated with a null cable.  You could swap
xmit and receive, but you couldn't reproduce collision detect or
heartbeat.  Heartbeat is no big deal, but what about collision detect?
For only two stations, why not go CSMA w/o CD??
	This question has been asked often enough, has anyone actually
tried doing this?  I haven't, but I'm getting curious.  I might get
curious enough to do it.  But before I do has anyone tried a null
transceiver cable with only xmit and rcv swapped?  How'd it work?

	Kent (in a silly mood) England
	Boston University

	[If you can run drop cables off Ts with thin-net, why not null
xcvr cables?]