RE: [Full-Disclosure] Ancient Trivia: +++ath0

["Cowles, Robert D." <rdc@xxxxxxxxxxxxxxxxx>]

The version I heard went something like:

Hayes implemented a "guard" ... they required a pause
between the "+++" and the following command. When
other manufacturers implemented the command set,
they had to make some small changes so they could
claim they hadn't *completely* ripped off the Hayes
command set ... they left out the requirement for 
the pause.  So, on lots of non-Hayes modems, you could
get them to hang up by just sending that string as data
(or including it as data in a ping packet).

Bob Cowles

> -----Original Message-----
> From: psz@xxxxxxxxxxxxxxxxx [mailto:psz@xxxxxxxxxxxxxxxxx] 
> Sent: Wednesday, March 17, 2004 6:17 PM
> To: full-disclosure@xxxxxxxxxxxxxxxx; lscharf@xxxxxxxxxx
> Subject: Re: [Full-Disclosure] Ancient Trivia: +++ath0
> 
> Luke Scharf <lscharf@xxxxxxxxxx> wrote:
> 
> > As the old BBS'ers and even older folks know, the string 
> "+++ath0" will
> > disconnect a modem. ...
> > Does anyone know what versions of windows had this 
> particular bug in the
> > PPP implementation?  Were any other systems affected?
> 
> I guess that the problem is not so much an issue in PPP (on 
> the client PC
> or at the ISP server), but the settings of both modems. To 
> fix, you need
> 
>   +++ats2=255
> 
> on both: see e.g.
> 
>   
> http://www.tldp.org/HOWTO/Remote-Serial-Console-HOWTO/modem-ha
> yes.html#MODEM-HAYES-ATTENTION
> 
> for details. (Also, there was a discussion on BugTraq at the end of
> September 1998, maybe it would be useful to look in the archives?)
> 
> Cheers,
> 
> Paul Szabo - psz@xxxxxxxxxxxxxxxxx  
> http://www.maths.usyd.edu.au:8000/u/psz/
> School of Mathematics and Statistics  University of Sydney   
> 2006  Australia
> 
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