User Manual

Modems Modem and SCS Interaction
9-11
To enable error correction, use the following command:
Figure 9-11: Enabling Error Correction
Note: For this command’s complete syntax, see Define Ports Modem Errorcorrection
on page 12-98.
When error correction is enabled on a port, the SCS will send a string to the modem to instruct it to enable
error correction. When error correction should be disabled, a disable string may be sent. The default enable
and disable strings vary, dependent upon the modem profile used. To display the default strings for a
particular modem profile, use the List Modem command.
To modify these strings, use the Define Ports Modem Errorcorrection command. The first string
specified is the disable string; the second is the enable string.
Figure 9-12: Changing the Disable and Enable Strings
9.4.7 Modem Security
If security precautions aren’t properly configured, unauthorized callers may be able to gain access
regardless of the port’s security measures. In order to prevent this, the following features should be enabled:
◆ If a remote user hangs up without logging out, the modem will sense the loss of carrier, and deassert
the DCD signal. The server will then log the port out.
◆ If the remote user logs out, the server will force the modem to hang up immediately and reset.
These items should be carefully verified for each port that a modem is attached to, even if a preconfigured
modem profile is used.
Dialback security, discussed on page 9-12, can be used in conjunction with these techniques on modem
ports for an additional layer of security.
The Ports and Security chapters cover security features in detail. The best tools for securing modem ports
are username and password pairs, server passwords, and idle timeouts.
9.4.8 Autostart
A port with Autostart and modem control enabled will not run the specified mode (for example, PPP) until
the modem asserts the DCD signal. This prevents the port from sending data to the local modem before a
remote modem is connected.
Note: For information on Autostart or the DCD signal, see Chapter 8, Ports.
Local>> DEFINE PORT 2 MODEM ERRORCORRECTION ENABLED
Local>> DEFINE PORT 2 MODEM ERRORCORRECTION “&q5” “q0”