Technical data

Managing Peripheral Devices
8.7 Managing Modems
• On a DECserver, configure the port using the following commands:
DECserver> SET PORT n MODEM ENABLE
DECserver> SET PORT n FLOW CONTROL XON ENABLE
DECserver> SET PORT n AUTOBAUD ENABLE
where n is the port number.
The commands enable the modem, XON, and autobaud. These commands
require privileges on the DECserver.
5. Ensure security with your modems.
Dial-in lines allow remote, unauthorized users access to your system. You
need to maintain consistent security and good system and user password
management to keep your system secure from unauthorized users.
The following list contains some ways to increase security on your system:
• You can configure a DECserver with a password to prevent a modem from
accessing any other feature. This password prevents an unauthorized
user from accessing or seeing any information about the local network
configuration until after the user enters the password. You can enable
this password on specific ports.
• With OpenVMS, you can establish a system-wide password requiring the
user to specify a password before the system prompts for a password.
This additional password helps reduce the security risk caused by users
with poor passwords. You can enable a system-wide password on specific
host ports.
• With OpenVMS, you can establish minimum password lengths, and you
can enable system-generated passwords. These measures can help reduce
the security risk caused by users with poor passwords.
• Always use and configure some form of modem control. Without modem
control, a telephone connection that is disconnected for any reason might
be left logged into the host, and a subsequent modem caller will receive
the logged-in session without specifying a password. Also, without modem
control, the host cannot request that a modem session be dropped when
certain system events such as a process logout occur.
These and other techniques for protecting your system from unauthorized
access are discussed in detail in the OpenVMS Guide to System Security.
8.7.3 Troubleshooting Modems
In troubleshooting any serial communications problems, particularly those
problems with a modem, attempt to isolate the problem as much as possible,
testing one component, wire, or device at a time.
Table 8–9 contains some general troubleshooting suggestions, but it is not a
complete list. Basic serial communications test equipment such as a serial-line
break-out box, can often help you locate communications and wiring problems.
For further assistance, contact your local hardware support organization.
Managing Peripheral Devices 8–33