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Chapter FourIntroduction to Firewalls

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Overview

Identify common misconceptions about firewalls

Eplain w!y a firewall is dependent on an effective

security policy

"nderstand w!at a firewall does

#escribe t!e types of firewall protection

$eco%ni&e t!e limitations of firewalls

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Introduction

Firewalls and related tec!nical controls are a

fundamental security tool

Overview of t!e issues involved in plannin% and

desi%nin% firewalls Eac! individual firewall

( )ombination of software and !ardware components

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Firewalls Eplained

Firewall

(*nyt!in% t!at can filter t!e transmission of pac+ets of

di%ital information

(*s t!ey attempt to pass t!rou%! an interface betweennetwor+s

asic security functions-

( Pac+et filterin%

*llow or deny pac+ets based on rules

(*pplication proy

Provide networ+ services to users w!ile bloc+in% direct

connections to t!em

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/isconceptions about Firewalls

Firewalls

( Permit aut!ori&ed traffic to pass t!rou%! w!ile

bloc+in% unaut!ori&ed and unwanted traffic

( Need constant maintenance to +eep up wit! t!elatest security t!reats

( 0or+ best as part of a multilayered approac! to

networ+ security

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*n *nalo%y- Office 2ower ecurity

Guard

Firewall performs same types of functions as does

a security %uard at a c!ec+point

( /onitors entry and eit points

( cans for viruses and repairin% infected files beforet!ey invade t!e networ+

( )an be confi%ured to send out alert messa%es and

notify staff of brea+4ins or if viruses are detected

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Firewall ecurity Features

*dvanced security functions offered by some

firewalls

( 6o%%in%

( VPN(*ut!entication

( !ieldin% !osts inside t!e networ+ so t!at attac+ers

cannot identify t!em and use t!em as sta%in% areas

for sustained attac+s( )ac!in% data

( Filterin% content t!at is considered inappropriate

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Firewall Networ+ Perimeter ecurity

Perimeter

( oundary between two &ones of trust

( lurred by

Etranet VPN

/obile devices

enefit of locatin% firewall at t!e perimeter

( et up a c!ec+point w!ere you can bloc+ viruses

and infected e4mail messa%es before t!ey %et inside

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Firewall Networ+ Perimeter ecurity

9cont:d;