AVIRA FIREWALL PREMIUM SECURITY SUITE, Руководство пользователя

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1. Basic Knowledge about the Firewall
A firewall works with network protocols like e.g. TCP, UDP, IT, etc.
A simple example for the building up of a connection is also called handshake
procedure. This example shows how a communication between two computers in the
Internet is build up.
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Computer A sends a package with the information that it wants to build up a
connection to computer B
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Computer B answers that it is ready
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Computer A confirms the answer of Computer B
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The connection between Computer A and B is now build up and the data
interchange can begin.
2. Explanation of the terms
TCP:
The Transmission Control Protocol (TCP) is an agreement (protocol) about the way
in which computers interchange data.
UDP:
The User Datagram Protocol (UDP) is a minimal connectionless network protocol. In
order to send the data with UDP to the right program on the target computer, so-
called ports are used. Therefore the port number of the service which contains the
data is also sent. Additionally UPD offers an integrity check by sending a check sum.
Thereby an incomplete transmission can be detected.
Flooding:
Flooding is a kind of overflow in a network caused by packages. Flooding can
paralyze the data transmission in a network (or of a single computer) as the
computer or the network is overflowed by a mass of requests and cannot react
anymore. You can compare that to a traffic jam on a freeway.
Ports:
A port can be compared to a house number. The difference is that a house, here a
computer can have several numbers. A port is a part of an address which assigns the
arriving package to an application.
Example:
Port 110 is responsible for the service POP3 and guarantees the access to the email
server. Special applications use port numbers which are assigned firmly by IANA and
are generally known. Usually the ports are numbered from 0 to 1023 and are called
Well Known Ports. Producers of applications can register ports for their own
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