Glossary
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firewall
A firewall protects a computer or local network against at-
tacks from the Internet.
Most firewalls work with packet filters, which merely check
the IP addresses and port numbers of incoming and outgoing
data packets and filter the packets according to prescribed
rules.
Within IPv4 networks, some firewalls also integrate addition-
al concepts like IP masquerading and NAT to decouple data
traffic by distinguishing strictly between the internal and ex-
ternal network.
Especially effective firewalls go even further, analyzing and
evaluating the contents of the packets and filtering them ac-
cording to prescribed rules. Such techniques may also in-
clude a Stateful Packet Inspection Firewall, for instance.
firmware
The firmware is the software of an electronic device, which is
stored in the device and controls its functions.
FTP
short for File Transfer Protocol
The File Transfer Protocol allows files to be exchanged be-
tween two computers in the Internet. A computer on which
the files are made available for downloading is called an “FTP
server”. A special program is required for downloading files,
known as an “FTP client”. Some web browsers contain FTP cli-
ents, but they are also available as independent software.
gateway
Gateway is a general term designating an interface between
two networks. Such a network interface can be realized using
a router or a bridge, for instance.
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