Great Circle Associates Firewalls
(August 1994)
 

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Subject: Finding Errant Modems
From: pascal @ netcom . com (Richard A Childers)
Date: Tue, 30 Aug 1994 19:27:01 -0700
To: Firewalls @ GreatCircle . COM

Don Jarmon notes :

"I would be interested in the tools use to identify modems.  I have
 been tasked to register all internal modems on our private exchange.
 Any help would be appreciated."

... in response to a prior posting, to wit :

> >and what happens when someone puts a modem on their unix box, ties it
> >to their deskset, and doesn't tell anyone?
>
> No, I just periodically sweep all numbers on our exchanges looking for
> unregistered (our policy required registration of all modems & special
> briefing/requirements for auto-answer).

				-=8=-

I have found it useful to add /etc/remote ( the modem entries ) to my
home-rolled equivalent of TripWire. You could also add /etc/ttya and
/etc/ttyb, to watch for the ports being touched by traffic flow.

( This would not defeat someone who knew how to create their own links
  to the device driver subsystem, or wrote something that didn't use
  /etc/remote, but 99.99% of your population will start with tip(1). )

				-=8=-

I've also often had the opportunity, (-:, to contract at sites where no
real idea of what all connected to the subnet, existed. Just today, as a
matter of fact, I once again had the pleasure of writing a little script
to iterate through the range of the subnet(s), pinging each absolute IP
address to see if there was anything turned on, using that IP address -
basically, I was assuming that /etc/hosts was worthless and starting from
scratch.

My experience with wiring rooms, telephone punchdown arrays and the like
is that documentation is similarly dated. So, why not use a daemon dialler
to probe every number in your corporate range of telephone lines and see
which ones answer, on a regular ( but unpredictable ) basis ?


-- richard

                 Law : The science of assigning responsibility.
              Politics : The art of _distributing_ responsibility.

   richard childers        san francisco, california        pascal @
 netcom .
 com

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