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INTRODUCTION

TYPES OF FIREWALL

HOW DOES A FIREWALL WORK

FIREWALL RULES

OVERVIEW

WHAT CAN A FIREWALL CAN/CANNOT DO

ARCHITECTURES FOR FIREWALL

CONCLUSION

INTRODUCTION• A firewall may be a hardware, software, or a combination of

both.• It is used to prevent unauthorized programs or Internet users

from accessing a private network and/or a single computer.

Types of firewall

SOFTWARE FIREWALL HARDWARE FIREWALL Protect a single computer Protect an entire network Usually less expensive, easier to

configure Usually more expensive, harder to

configure Implemented on the router level

Norton Internet Security Cisco PIXMcAfee Internet Security NetScreen

Outpost WatchGuardMs. ISA Server Check Point

HOW DOES A FIREWALL WORK• Inbound to or outbound from your computer.• Inspects each “packet” of data that arrives at either side of the

firewall.• Determines whether it should be allowed to pass through or if

it should be blocked.

sent

sentreceived

received

packets packets

How a firewall works ?• Sniffing Mode

– An attacker tries to compromise a service on the protectednetwork.

– The Firewall identifies the attempt.

• The FIREWALL can now:• Alert the admin• Harden the firewall• Or reset a TCP/IP connection

LOG

Alert

Reset

Fire Wall

FIREWALL RULES• Allow – traffic that flows automatically because it has been

deemed• Block – traffic that is blocked because it has been deemed

dangerous to your computer• Ask – asks the user whether or not the traffic is allowed to

pass through

WHAT CAN A FIREWALL DO?

• Focus for security decisions– Stop hackers from accessing our computer

• Can enforce security policy– Protects our personal information

• Limits your exposure– Blocks “pop up” ads and certain cookies

• Can log Internet activity efficiently– Determines which programs can access the Internet

• Can't protect you against malicious insiders• Can't protect you against connections that don't go through it• Can't protect against completely new threats• Can't protect against viruses

FIREWALL CAN…..• Stop hackers from accessing your computer.• Protects your personal information.• Blocks “pop up” ads and certain cookies.• Determines which programs can access the

Internet.• Block invalid packets.

FIREWALL CANNOT…• Cannot prevent e-mail viruses

– Only an antivirus product with updated definitions can prevent e-mail viruses.

• After setting it initially, you cannot forget about it– The firewall will require periodic updates to the

rule sets and the software itself.

FIREWALL PROTECTS FROM

• Remote login • SMTP session hijacking • Operating system bugs • Spam• E-mail bombs • Source routing

Architectures for Firewall

• Single-Box Architecture

Architectures for Firewall

• Screened Host Architecture

CONCLUSION• There are many vulnerabilities in the internet, so firewall

protects us from these vulnerabilities.• Firewall protect private files from the outsiders access.

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