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IT Baseline Protection Manual - The Information Warfare Site

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Data Transmission Systems Modem<br />

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7.2 Modem<br />

Description<br />

A modem is used to link a data terminal, e.g. a PC with other<br />

data terminals via the public telephone network to allow the<br />

exchange of information. A modem converts digital signals<br />

from the data terminal into analogue electric signals which<br />

can be transmitted by the telephone network. For two <strong>IT</strong> Modem<br />

systems to be able to communicate, they must be equipped<br />

with the required communication software.<br />

A distinction is made between external, internal and PCMCIA modems. An external modem is an<br />

independent unit with a separate power supply, usually connected to the <strong>IT</strong> system via a serial<br />

interface. An internal modem consists of a plug-in modem board without a separate power supply. A<br />

PCMCIA modem is a credit-card sized plug-in board normally connected to laptops via a PCMCIA<br />

interface.<br />

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

Threat Scenario<br />

<strong>The</strong> following typical threats are assumed for modem operation as part of <strong>IT</strong> baseline protection:<br />

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<strong>IT</strong>-<strong>Baseline</strong> <strong>Protection</strong> <strong>Manual</strong>: Otober 2000

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