1. FIREWALLS :
REAL TIME PROTECTION
M.Emin Özgünsür
07070001052
SOFL-102
2010, Izmir

2. 1) Why computers need to protect ?
2) Why we need firewall ?
3) How can 2 computers connect ?
4) What is the firewall types ?
5) What is the firewall ?
6) What can we use generally firewall types ?
7) What is the software firewall types ?
7.1) Packet filtering
7.2) Application level
7.3) Circuit level
8) What is firewall function ?
Table Of ContentsTable Of Contents

3. If a home or business computer owner bounds to a network or an
internet connection, their personal datas open to reach unauthorized
person who have a connection a network or an internet.
This situation will become harder to protect data security than to
provide local area network or internet data security. Because, a
system of computer how much having strong external relations, it will
become more undefend system.
Also,it is exposed to spies, thieves, hackers, thrill seekers, or various.So
that, users need to be increasingly vigilant of security issues.
Why computers need to protect ?Why computers need to protect ?

4. Why we need firewall ?Why we need firewall ?
Many entry points go towards to host, must be
guard with a simple login request.The most
sources of danger are databases, network files
and mailers.
However some protocols inadequate to provide
adequate service, its required from the local
users. So, this computer will take more attack. If
a computer user’s set a limit for a single
building, it will become harder for an foreigner
to trickle into system.
On the other hand, a computer which
connected to network, can be reached from
any point on the network.At the end of,
networks have constitute a security crossing
problem.Generally, one of the solution way
about computer data security is firewall.

5. How can 2 computers connect ?How can 2 computers connect ?
We can see it in Windows Operating System, “netstat -n “ command
to cmd. In this cmd we can see “ established “ word. Established
connections are correctly connecting with A machine to our machine.

6. What is the firewall types ?What is the firewall types ?
Firewalls are softwares or hardwares which provide permission
control, obstructing and filtering to unauthorized reaching come from
on network or on internet.
Its could be seperate three groups of software, hardware or both of
them to each other.

7. What is the firewall ?What is the firewall ?
Broadly speaking, a computer firewall is a software program that
prevents unauthorized access to or from a private network.
Firewalls are tools that can be used to enhance the security of
computers connected to a network, such as LAN or the Internet. They
are an integral part of a comprehensive security framework for your
network.

8. What is the firewall ?What is the firewall ?
In theory, a firewall absolutely isolates your computer from the
Internet using a "wall of code" that inspects each individual "packet"
of data as it arrives at either side of the firewall — inbound to or
outbound from your computer — to determine whether it should be
allowed to pass or be blocked.

9. What can we use generally firewall types ?What can we use generally firewall types ?
Hardware firewalls are expensive for home users. Hardware firewalls
are generally used by data centers which hosting datas on the
internet.
The most antiviruses have connected with firewalls and each
computer users have an antivirus programs. So home users generally
use software firewalls.

10. What is the software firewall types ?What is the software firewall types ?
Firewalls could be classifying three main categories. It could be
arranging generally, packet filtering, circuit gateways, and
application gateways.
Some other sources talked about fourth filtering of statefull inspection
firewalls. Traditionally, firewalls are placed between an organization
and the outside world. But a large organization may need internal
firewalls as well to isolate DMZ (also known as administrative
domains).
DMZ which known De Militarized Zone network, is created out of a
network connecting two firewalls when two or more firewalls exist in
the networks connecting the firewalls.

11. What is the packet filtering gateways ?What is the packet filtering gateways ?
First category of firewalls is packet - filtering gateways. This type
firewalls control IP protocol, IP adress and port number include own
rules.
From there, the firewall would start at the top of the ruleset and
work down through the rules. In the table a sample of a packet filter
firewall ruleset for an imaginary network is shown.

12. What is the application – level gateway ?What is the application – level gateway ?
Second category of firewalls is application - level gateway. It is
opposite of firewall designs.
In this type firewall, its system prefer to using general specified
mechanism to allow many different kids of traffic to flow.
The code, can be used for each
desired applications. This type
firewalls search some protocols
which work in application layer in
OSI models. If we describe OSI
models, it is a seven layer’s standard
which using by computers for
communicating in networks.

13. What is the circuit – level gateway ?What is the circuit – level gateway ?
Third category of firewalls is circuit - level gateway. Circuit gateways
relay TCP connections. The caller connects to a TCP port on the
gateway, which connects to some destination on the other side of the
gateway. During the call the gateway’s relay programs copy the
bytes back and forth: the gateway acts as a wire. In some cases a
circuit connection is made automatically.
For example, we have a host outside our gateway that needs to use
an internal printer. We have told that host to connect to the print
service on the gateway. Our gateway is configured to relay that
particular connection to the printer port on an internal machine.

14. What is firewall function ?What is firewall function ?

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M.Emin Özgünsür