Download - Firewall New
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Firewalls
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CONTENTS
l What is firewall
l Types of firewall
l What firewall protects us froml Firewall Limitations
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What is firewall ?
LANINTERNET
A firewall is simply a software orhardware device or a combination of
both that filters the information comingthrough the Internet connection intoyour private network and/or a single
computerActs as a security gateway between twonetworks
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Hardware Firewalls
Protect an entire network
Implemented on the routerlevel
Usually more expensive,harder to configure
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Software Firewalls
Protect a single computer
Usually less expensive
easier to configure
PC
Internet
Firew
all
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Popular hardware & softwarefirewalls
Software Firewall Hardware Firewall
Ms. ISA Server Cisco PIX
Norton Internet Security Blue Coat
Mcafee Internet Security Cyberoam
ZoneAlarm Check Point
Kerio NetScreen
BlackICE defender D-link SECURESPOT
Outpost WatchGuard
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TYPES OF FIREWALL
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Evolution of Firewalls
Packet
Filter
StatefulInspection
Stage of
Evolution
ApplicationProxy
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Packet Filters
l Very basic
l Also called Network Layer Firewalls
l Not allowing packets to pass through thefirewall unless they match theestablished ruleset.
l If it meets the regulations the firewalls
forwards it to the another networkotherwise discarded.
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ADVANTAGES AND DISADVANTAGE S OFPACKET FILTERS
Advantag
es:CheapDoes not affect the network performance
Disadvantages:Difficulty of setting up packet
filter rulesAllows direct connections to internal hosts byexternal clients Offers no user authentication
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Application levelgateway(Proxy server)
l Information from the Internet is retrievedby the firewall and then sent to the
requesting system and vice versa.l proxy servers sit between the client and
actual servier. Both the client and server
talk to the proxy rather than directly witheach other.
l The proxy server effectively hides thetrue network addresses.
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Advantages:
Higher security than packet filters Blocks on content, not just URL
Easy to log and audit all incoming traffic Direct connections between internal and
external hosts are disallowed. User-level authentication is supported.
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Disadvantages
ExpensiveSlower than packet filters
Affecting network performanceRequires modification to client software
application
Some protocols arent supported by proxyservers
Some proxy servers may be difficult toconfigure and may not provide all the
protection you need.
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Stateful Multilayer Inspection Firewall
A newer method that doesn't examine thecontents of each packet but insteadcompares certain key parts of the packet
to a database of trusted information. stateful packet inspection as it maintains
records of all connections passing through
the firewall and is able to determine packetis valid or not
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qMost secure firewall
DISADVANTAGES
qExpensiveqMust be set up byprofessional
ADVANTAGES
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What firewall protects usfrom
n Remote login
n Application backdoors
n SMTP session hijacking
n Operating system bugs
n Denial of servicen E-mail bombs
n Viruses
n SPAMs
n Trojans
n ICMP bombing
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l just because you have a firewall, dont believe you arefully protected against malware
l cannot protect against transfer of all virus infectedprograms or files
l After setting it initially, you can forget about it The firewall will require periodic updates to the
rulesets and the software itself
l Cannot prevent e-mail viruses
Only an antivirus product with updated definitions canprevent e-mail viruses
Firewall Limitations
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Thankyou