It would appear that the modem I am using for this dialin is behaving
badly, despite the S12 register being factory default set at 50/50ths
second, it seems that the software blithly ignores it.
Solution was to set the S2 register from 43 to 255 so that it totally
ignores the "+++", and use the hardware signal drop to initiate the
hangup, which it was doing anyway.
--
Howard.
______________________________________________________
LANNet Computing Associates <http://www.lannet.com.au>
On Thu, 14 Sep 2000, DaZZa wrote:
> On Wed, 13 Sep 2000, Howard Lowndes wrote:
>
> > I have a user dials into my system to retrieve mail. As soon as the first
> > email is sending the line hangs up.
> >
> > I have just realised that this email was one discussing the DD0S attacks I
> > was suffering and mentions the +++ATH0 modem string in the text.
> >
> > Could the existence of this string be causing the hangup, it just seems
> > strange that it would do such a thing, perhaps one of the two modems
> > is not respecting the 1 second guard time? If it is then I know what the
> > fix is.
>
> It certainly could if one of your modems is the cheap nasty variety which
> doesn't impliment the full Hayes command set.
>
> This type of "attack" was common for some time until modem manufacturers
> woke up to it.
>
> Check your guard times. It's almost dead certain.
>
> DaZZa
>
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