Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!spdcc!dyer
From: dyer@spdcc.COM (Steve Dyer)
Newsgroups: comp.dcom.modems
Subject: Re: 9600 Mod
Keywords: SLIP
Message-ID: <2603@spdcc.SPDCC.COM>
Date: 18 Feb 89 00:09:07 GMT
References: <568072@vaxa.uwa.oz> <4035@alvin.mcnc.org> <13974@bigtex.cactus.org> <896@muffin.cme.nbs.gov>
Reply-To: dyer@ursa-major.spdcc.COM (Steve Dyer)
Organization: S.P. Dyer Computer Consulting, Cambridge MA
Lines: 23

In article <896@muffin.cme.nbs.gov> libes@cme.nbs.gov (Don Libes) writes:
>Lastly, does any modem manufacture spoof SLIP?  (Were you jesting
>about Telebit, or do you actually know if they are going to do it?)

Since IP is a datagram protocol, there really isn't much to 'spoof',
ACK-wise (no ACKs), and spoofing TCP would seem to require an
arbitrarily large amount of state to spoof every VC that passed through
the modem pair.  It would also suggest that it would wreak havoc with
RTT calculations.  Remember that UUCP, [xy]modem and kermit spoofing
really depends on the fact that there is a single pseudo-half-duplex
protocol providing only one "virtual circuit" between the two Telebits.

However, for simple point-to-point set-ups, you could imagine a mode
where a lot of the IP header could be dispensed with (though I think
host support for this is probably a better idea.)  Also, Telebit needs
to do some work optimizing its internal packet sizes and turn-around
times for connections used for SLIP.  This isn't really "spoofing"
but it would help.

-- 
Steve Dyer
dyer@ursa-major.spdcc.com aka {ima,harvard,rayssd,linus,m2c}!spdcc!dyer
dyer@arktouros.mit.edu