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From: cottrell@nbs-vms.arpa (COTTRELL, JAMES)
Newsgroups: net.unix-wizards
Subject: RCP
Message-ID: <1712@brl-smoke.ARPA>
Date: Tue, 11-Mar-86 20:45:30 EST
Article-I.D.: brl-smok.1712
Posted: Tue Mar 11 20:45:30 1986
Date-Received: Fri, 14-Mar-86 06:49:12 EST
Sender: news@brl-smoke.ARPA
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/*
> Regarding the BSD "feature" of trashing files if you happen
> to forget which host you are on and do an rcp of a file onto
> itself:
> 
	[mapping explained]

> To facilitate this type of mapping, we (re)introduced the
> concept of machine-id, or mid.
> 
> Now, with every host in our network assigned a unique mid,
> it is an easy matter to fetch the mids of both files, and
> thus protect against the BSD behavior.
> 
> And a side comment/question:  The "hostid" concept of 4.2BSD
> would seem to have been a start at "machine-ids", but then
> they went and equated it with Internet address (which of
> course completely defeats the benefits).  Anybody know what
> Berkeley had in mind for "hostid"?

I jumped to respond at this a bit too quickly I suppose.
The `internet address' should be unique unless you are a gateway
or connected to more than one network. In any case, picking the
`dominant' network and sing its internet address as `hostid'
should work. 
 
> PS:  Or is that "kramden"?

I don't know. But at least I can spell `Norton'.

	jim		cottrell@nbs
*/
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