IT Baseline Protection Manual - The Information Warfare Site

Safeguard Catalogue - Communications Remarks
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between the inner packet filter and the Application Gateway (see Figure 1).
The Application Gateway and the outer packet filter provide sufficient
protection against attacks from the insecure network. The fax server is
protected against attacks from the internal network by the inner packet filter.
Text zum Bild
zu schützendes Netz Network requiring protection
Packet Filter Packet filter
Faxserver Fax server
Dual-homed Application Gateway Dual-homed Application Gateway
unsicheres Netz Insecure network
zentral verwaltet Centrally administered
Figure 1
Under all other firewall combinations, especially those in which there is only
one packet filter, or when there is no firewall, the fax server should be linked
straight into the secure network. If the protection requirement is such that the
resulting residual risk is viewed as unacceptable, then either a separate packet
filter should be provided or else the private branch exchange must be
configured so that only outgoing connections are permitted. In the latter case,
a conventional fax machine or a stand-alone system with an appropriate fax
application must be used for incoming fax transmissions. In either case
incoming fax transmissions must then be forwarded manually to recipients.
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IT-Baseline Protection Manual: Oktober 2000
Position of fax server
without suitable firewall