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Security
11-33980-A2-GB30-20 November 1996
NOTE
While pulse dial can be used to
originate the call, DTMF tones
must be used for the password.
This can be accomplished by
using the P and T modifiers
appropriately. Refer to the Dial
command in Chapter 13,
AT
Command Set and S-Registers
,
for more on modifiers.
This method of password entry requires that the
answering modem be a 3800
Plus modem. The modem
must be configured for VF-side password entry and the
originating user must know the correct VF-side password.
The originating modem can be another 3800Plus modem
or any vendor’
s modem.
Some originating modems may not recognize the
W modifier as a wait for second dial tone. If your call
disconnects due to a VF Password T
imeout or an
Unknown VF Password, first verify that the answering
3800Plus modem’s VF Prompt Type is set for 2nd Dial
Tone. Next, verify that the Dial Tone Detect configuration
option in the originating modem is enabled. Third, insert
several Pause (,) modifiers into the dial string instead of
the W modifier. (For the 3800Plus
modem, each Pause,
which is determined by the Pause Time configuration
option (S8), is equal to 2 seconds.) This allows a delay
between the processing of the phone number by the
answering modem and the transmission of the VF-side
password by the originating modem.
Some experimentation may be necessary to determine
the number of pauses necessary for your call.
DTE-Side Passwords
DTE-side password entry requires the originating user
to supply a valid password via his DTE. This method of
password entry occurs after the modems’ training
sequence, but before normal connection. The modems
must be configured for asynchronous operation to use this
type of security.
When using DTE-side password entry
, the modems go
through their normal training and error control
negotiation. Once complete, the answering modem
requests a valid password from the originating user. The
originating user must enter, via the DTE, a password that
can consist of digits and case-insensitive letters. Note that
DTE passwords can be from 1 to 6 characters in length.
The answering modem verifies the password against its
password database table, and if valid, completes the data
connection, thus allowing DTE data to be passed. As with
VF-side password entry
, the answering modem must be a
3800Plus modem and the originating modem can be either
a 3800
Plus modem or any vendor’
s modem.
The following example illustrates the format of
DTE-side password:
abc123 (press Enter)
Where: abc123 is a 10-alphanumeric character
number. characters used for DTE-side
passwords are case insensitive.
Combination of VF-Side and
DTE-Side Passwords
The previously described methods of password entry
can be combined to provide two layers of security. In this
case, the modems negotiate VF-side password entry prior
to training. If successful, the modems connect and then
prompt the originating user for a valid password. If
correctly entered, the modems connect.