7.2 Modem


A modem is used to link a data terminal, e.g. a PC with other data terminals via the public telephone network to allow the exchange of information. A modem converts digital signals from the data terminal into analogue electric signals which can be transmitted by the telephone network. For two IT systems to be able to communicate, they must be equipped with the required communication software.

A distinction is made between external, internal and PCMCIA modems. An external modem is an independent unit with a separate power supply, usually connected to the IT system via a serial interface. An internal modem consists of a plug-in modem board without a separate power supply. A PCMCIA modem is a credit-card sized plug-in board normally connected to laptops via a PCMCIA interface.

This chapter does not deal with data transmission via ISDN (c.f. Chapter 8, PBX System) Modem

Threat Scenario

The following typical threats are assumed for modem operation as part of IT baseline protection:

Force Majeure:

Human Failure:

Technical Failure:

Deliberate Acts:

Recommended Countermeasures (S)

For the implementation of IT baseline protection, selection of the required packages of safeguards ("modules") as described in chapters 2.3 and 2.4, is recommended.
The safeguards package for "Modem" is presented in the following.






© Copyright by Bundesamt für Sicherheit in der Informationstechnik 2000

Last Update on 6 April 2000