[VPN] Securing Modems

[Daniel Linder]

--- kris Gill <kclsg98 at yahoo.com> wrote:
> Does anyone know of solutions to Securing dial modems
> against such problems as war-dialers? I know of a
> hardware product that drops calls within 1/2 a second,
> but I was wondering if there were other cheaper ways
> of doing this. Any help is appreciated.

If you have the time and programming prowess, you could setup a server
to listen for the "RING" to come in from a modem (set to NOT auto
answer).  You could then have that server do any number of things:
Option A: Have it wait 30 seconds and enable the modem auto-answer;
disable auto-answer after another 60 seconds. (This prevents the simple
war-dialer script, but if they *know* it is there, then they will
figure this out.)

Option B: When the "RING" comes in, have the system dial a
predetermined call-back number.  If your modem numbers are not on a
one-to-one ratio with the users, then you could possibly query the
Caller ID feature that some modems have and do a quick lookup to
determine a call back number based on where they called from.

Option C: If you are staffed 24x7, have a trusted help-desk staff
person login and enable the auto-answer.  The "disable auto-answer"
could be automated to turn off after you disconnect.

I am sure there are more options!

Dan

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