Great Circle Associates Firewalls
(April 1995)
 

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Subject: Re: Secure Modem Pool
From: Christian Wettergren <cwe @ it . kth . se>
Date: Wed, 26 Apr 95 09:37:17 +0200
To: FV Admin mail <fvadmin @ sgf . fv . com>
Cc: Ari Shamash <ari @ soscorp . com>, Steve England <se @ adv . sbc . sony . co . jp>, firewalls @ greatcircle . com
In-reply-to: Your message of Tue, 25 Apr 95 18:15:52 BST. <Pine . 3 . 89 . 9504251839 . A3178-0100000 @ sgf . fv . com>

| Well, that's just *broken*.  Either that, or it's from the way-back days 
| when the callee couldn't hang up on a call if the caller stayed off 
| hook.  Nowadays, there's no possible reason why a callback modem wouldn't 
| just hang up the line itself before picking up, listening for dial-tone, 
| and dialing.
| 
| The other means of breaking into a callback modem is to have the phone 
| company add call forwarding to the employee's phone (who checks?), have it 
| forwarded to the cracker's modem, and then call in.  --Darren

A few friends of mine had a look at a dialback modem, and claimed that 
the modem would have trouble to separate incoming from outgoing calls 
during certain periods of the "handshake". I guess this varies with each modem
and PTT.

/Christian Wettergren



References:
Indexed By Date Previous: Re: Firewall failure modes (was Re: performance)
From: "Marcus J. Ranum" <mjr @ tis . com>
Next: Firewall testing (was Firewall failure modes, etc)
From: jbarnes @ aztec . co . za (Jay Barnes)
Indexed By Thread Previous: Re: Secure Modem Pool
From: FV Admin mail <fvadmin @ sgf . fv . com>
Next: Re: Secure Modem Pool
From: ari @ soscorp . com (Ari Shamash)

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