Introduction of firewall slides

 Define what is firewall ?
 Need of firewall
 Types of firewall
› Hardware firewall
 Advantage and disadvantage
› Software firewall
 Advantage and disadvantage

 Types of firewall techniques
› Packet filter
 Drawback of packet filtering
› Application gateway
 advantage
› Circuit-level gateway
› Bastion host
 What a personal firewall can do
 What a personal firewall can not do
 Manufacturing companies

 Firewall is device that provides secure
connectivity between
networks(internal/external).

 A firewall may be a hardware, software of a
combination of both that is used to prevent
unauthorized program or internet users from
accessing a private network or a single
computer.
 All message entering or leaving the intranet
pass through the firewall, which examines
each message & blocks those that do not
meet the specified security criteria.

 To protect confidential
information from those
who do not explicitly need
to access it.
 To protect our network &
its resources from
malicious users &
accidents that originate
outside of our network.

 Hardware firewall
 Software firewall

 It is a physical device.
 It can be installed
between the modem and
computer.
 It can be incorporated
into a broadband router
being used to share the
internet connection.

 Protect an entire network.
 Usually more expensive, header to configure
 E.g.- Cisco pix, netscreen, watchfuard etc.

 Uses very little system resources.
 More secure
 Enhanced security control
 Dedicated hardware firewalls are typically more
reliable
 Easy to disable or remove
 Work independently of associated computer
system.

 Install process is more demanding both
physically and mentally.
 Takes up physical work space
 More expensive
 Harder to upgrade and repair

 It is a software
application.
 It is installed onto the
computer system that
you wish to protect .

 Protect a single computer
 This is usually the computer with modem
attached to it.
 Usually less expensive, easier to configure
 E.g.- Norton internet security, MacAfee
internet security etc.

 Considerably cheaper or even free.
 Simple to install and upgrade
 Requires no physical changes to hardware
or network
 Ideal for home/family use
 Takes up no physical space.

 Software may crash or be incompatible with
system
 Can be difficult to completely disable &
especially remove
 Software bugs may compromise security
 Can be resource hungry
 Incompatibilities with OS.

 Packet filter
 Application gateway/proxy server/proxy
application gateway
 Circuit-level gateway
 Bastion host

 It looks at each packet entering or leaving
the network accepts or rejects it based on
user-defined rules.
Applications
Presentations
Sessions
Transport
Data Link
Physical
Data Link
Physical
Router
Applications
Presentations
Sessions
Transport
Data Link
Physical
Network Network

 Packet filtering is fairly effective &
transparent to users, but it is difficult to
configure.
 In addition, it is susceptible to IP spoofing.

 Drawback of packet filtering technique:-
i. Packet filtering rules can be complex.
ii. Logging facility is not provided by such
firewall.
iii. If TCP/IP packet filtering is not implemented
fully, it can lead to security hole.
iv. Cannot handle RPC (remote produce calls)

 In such type of firewall remote host or
network can interact only with proxy server,
proxy server is responsible for hiding the
details of the internal network i.e. intranet.
 Users uses TCP/IP application, such as FTP
& Telnet servers.

Applications
Presentations
Sessions
Transport
Data Link
Physical
Network
Data Link
Physical
Applications
Presentations
Sessions
Transport
Data Link
Physical
Application Gateway
Applications
Presentations
Sessions
Transport
Network Network
Telnet HTTPFTP

 This is very effective, but can impose a
performance degradation.

 Advantages of application gateway:-
i. Less complex filter rules
ii. Cost effectiveness
iii. Robust authentication & logging facility
iv. Proxy authenticates only those services for
v. Which it is configured/installed.

 It is a stand alone application.
 It does not permit end-to-end TCP connection. it
sets up 2 TCP connection:-
• Between itself and a TCP user on an inner host.
• Between itself and a TCP user on an outer host.

 Bastion host is a special purpose computer
on a network specifically designed and
configured to withstand attacks.

 It generally hosts a single application,
provides platform for application gateway
and circuit-level gateway.
 It supports limited/specific applications to
reduce the threat to the computer.
 Include application-Telnet, SMTP, FTP

 Stop hackers from accessing your
computer.
 Protect your personal information.
 Blocks “pop up” ads and certain
cookies.
 Determines which programs can
access the internet.
 Block invalid packets.

 Cannot prevent e-mail
viruses
-only an antivirus product
with update 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.

 Cisco system, Inc.
 Nortel networks corporation
 Juniper networks, Inc.
 MacAfee, Inc.
 3com corporation
 Citrix systems, Inc

Introduction of firewall slides

Introduction of firewall slides

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Introduction of firewall slides