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RE: Ancient Trivia: +++ath0
From: <Glenn_Everhart () bankone com>
Date: Thu, 18 Mar 2004 13:15:12 -0500

The <delay>+++<delay> scheme, using time delays, was more like the old
break signal, not really like a string that would not transmit...at least
on modems that used the delay. You could sometimes kinda/sorta get
something like that to work by switching to 110 baud and sending nulls,
then switching back to whatever rate you were using, but normal
protocols that sent text would very rarely have packet boundaries just
at either end of the sequence. Also the modems let you set the break length
and the character to use in case "+++" was inconvenient for some reason. 
Certainly anything in the ASCII character set other than null would have
been ok. Don't know about null (or rubout for that matter).

-----Original Message-----
From: Luke Scharf [mailto:lscharf () aoe vt edu]
Sent: Thursday, March 18, 2004 8:49 AM
To: full-disclosure () lists netsys com
Subject: Re: [Full-disclosure] Ancient Trivia: +++ath0

On Wed, 2004-03-17 at 21:30, cstone wrote:
* = Hayes has a patent on a scheme to protect against unintentional
triggering of the escape sequence; on their modems, you have to
wait a specific amount of time before and after the +++ before
issuing a command.  

Doh!  I thought that there was an easier way to escape the escape
sequence.  Too much Unix -- '\+\+\+' :-)

But, still, isn't a string of characters that the modem won't transfer
something that the communications system on a PC should handle?

Anyway, I'm starting to get nostalgic about the old BBS days -- maybe I
should put my old one up again?  But, they just haven't the same since I
started using the WWW, and telnet BBSs just don't do it for me.


Luke Scharf, Systems Administrator
Virginia Tech Aerospace and Ocean Engineering

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