Firewall & packet filter

1. GUJARAT TECHNOLOGICAL
UNIVERSITY
Subject : Cyber Security
(2150002)
Topic : Firewall and Packet
filter

3. Contents
 What is FireWall ?
 Types of firewall
 Firewall Rules
 How does a Firewall work?
 What a personal firewall can do ?
 Introduction to packet filter
 Functions of Packet Filter
 Usage of Packet Filters
 Manufacturing companies
 CONCLUSION

4. What is FireWall ?
 Firewall is device that provides secure connectivity between
networks (internal/external).
 A firewall may be a hardware, software, or a combination of both
that is used to prevent unauthorized programs or Internet users from
accessing a private network and/or a single computer.

5. Types of
firewall
Hardware
firewall
Software
firewall

6. 1.Hardware 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.

7. 2.software firewall
 It is a software application.
 It is installed onto the computer system that you wish to 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.

8. 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

9. 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.

10. How a firewall works ?
 Sniffing Mode
1) An attacker tries to compromise a service on the protected network.
2) The Firewall identifies the attempt.
LOG
Alert
Reset
Fire Wall

The FIREWALL can now:
• Alert the admin
• Harden the firewall
• Or reset a TCP/IP connection

11. What a personal firewall can do ?
 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.

12. Sample Network to Be Protected by a Firewall

13. Introduction to packet filter
 Packets: discrete blocks of data; basic unit of data handled by a network
 Packet filter: hardware or software designed to block or allow transmission of
packets based on criteria such as port, IP address, protocol
 To control movement of traffic through the network perimeter, know how packets
are structured and what goes into packet headers
 It looks at each packet entering or leaving the network accepts or rejects it based
on user-defined rules.
 Packet filtering is fairly effective & transparent to users, but it is difficult to
configure.
 In addition, it is susceptible to IP spoofing.

14. Applications
Presentations
Sessions
Transport
Data Link
Physical
Data Link
Physical
Router
Applications
Presentations
Sessions
Transport
Data Link
Physical
Networ
k
Networ
k

15. Functions of Packet Filter
 Control: Allow only those packets that you are interested in to pass
through.
 Security: Reject packets from malicious outsiders
 Watchfulness: Log packets to/from outside world

16. Usage of Packet Filters
Filtering with incoming or outgoing interfaces
E.g., Ingress filtering of spoofed IP addresses
Egress filtering
Permits or denies certain services
Requires intimate knowledge of TCP and UDP port utilization
on a number of operating systems

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

18. Conclusion
 Don’t make the mistake of thinking that no one will attack your network, because
with the rise in automated attack tools, your network is as much at risk as every
other network on the Internet.
 The need for firewalls has led to their ubiquity. Nearly every organization
connected to the Internet has installed some sort of firewall.
 When choosing and implementing a firewall solution, make a decision based on the
organization's needs, security policy, technical analysis, and financial resources.
Solutions available today utilize different types of equipment, network
configurations, and software.