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:
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.