IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Organisation Remarks
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mission rates should be used for large quantities of data. Transmission rates
of more than 2400 bits/sec. make tapping more difficult.
A check must subsequently be made as to whether the interface of the IT
system intended for connection to the modem allows operation at speeds
above 9600 bits/sec.
When selecting the modem, it should be ensured that performance
characteristics, which are of importance for the transmission rate actually
attained, are standardised. These are standards for the transmission rate,
such as V.32bis for 14400 bits/sec. and protocols for transmission
optimisation using data compression and error correction, such as MNP 5
or V.24bis.
- Instruction set
Most modems today use the manufacturer-dependent Hayes-standard (also
termed AT standard). The widespread application of this standard allows
largely error-free communication between compatible modems. When
purchasing modems of the latest generation, it should be noted that the
promised high transmission rates can often only be achieved if machines
from the same manufacturer are used on both sides.
- Manual
A detailed and clearly-written manual is important for rapid installation
and the best possible configuration of a modem.
- Security mechanisms
Modems can incorporate a large variety of security features, e.g. password
mechanisms and call-back functions. Some modems even offer the
possibility of encrypting data intended for transmission.
The purchase of a modem with an encryption option is advisable if large
quantities of data need to be transmitted within an organisation with
scattered premises. This on-line coding requires less organisational effort
than the encryption of data by means of auxiliary products. General
statements on the security of the algorithms used are not possible. For IT
baseline protection, the DES algorithm offers a sufficient degree of
security given an appropriate key management.
As regards security, the widely offered call-back function is advantageous
in that it easily allows unauthorised callers to be repudiated (also refer to S
5.30 Activating an existing call-back option).
Additional controls:
- Are IT users and the purchasing department aware of these instructions?
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IT-Baseline Protection Manual: Oktober 2000