A firewall is hardware or software that protects private networks and computers from unauthorized access. There are different types of firewalls including packet filtering, application-level gateways, and circuit-level gateways. Firewalls work by inspecting packets and determining whether to allow or block them based on rules. They can protect networks and devices from hackers, enforce security policies, and log internet activity while limiting exposure to threats. However, firewalls cannot protect against insider threats, new types of threats, or viruses. Firewall configurations should be tested to ensure they are properly blocking unauthorized traffic as intended.

1. Presentation :’Firewalls’Presenters :-Gagandeep SinghKarandeepVohraPuneetpal Singh1

2. Table of Contents2IntroductionHOW FIREWALL WORKSTypes of Firewalls MAKING THE FIREWALL FITTESTING A FIREWALL CONFIGURATIONCONCLUSIONREFERENCES

3. IntroductionIs hardware, software, or a combination of bothused to prevent unauthorized programs or Internet users from accessing a private network and/or a single computer.3

4. Hardware vs. Software Firewalls4Hardware FirewallsProtect an entire networkImplemented on the router levelUsually more expensive, harder to configureSoftware FirewallsProtect a single computerUsually less expensive, easier to configure

5. How does a software firewall work?5Inspects each individual “packet” of data as it arrives at either side of the firewallDetermines whether it should be allowed to pass through or if it should be blocked

6. Firewall Rules6Allow – traffic that flows automatically because it has been deemedBlock – traffic that is blocked because it has been deemed dangerous to your computerAsk – asks the user whether or not the traffic is allowed to pass through

7. What Can a Firewall Do?Focus for security decisionsStop hackers from accessing your computerCan enforce security policyProtects your personal informationLimits your exposureBlocks “pop up” ads and certain cookiesCan log Internet activity efficientlyDetermines which programs can access the Internet7

8. What Can't a Firewall Do?Can't protect you against malicious insidersCan't protect you against connections that don't go through itCan't protect against completely new threatsCan't protect against viruses8

9. Types of Firewalls Packet Filtering FirewallApplication level GatewayCircuit level gateway9

10. Architectures for Firewall Single-Box Architecture10

11. Screened Host Architecture11

12. Making The Firewall FitIP addressDomain namesProtocolsPorts12

13. What It Protects You FromRemote login SMTP session hijacking Operating system bugs SpamE-mail bombs Source routing 13

14. Security Strategies implemented Default DenyProhibit all communication that is not expressly permittedDefault PermitPermit all communication that is not explicitly prohibitedLeast Privilegereduces the authorization level at which various actions are performedDefense in Depthsecurity approach whereby each system on the network is secured to the greatest possible degreeChoke Pointforces attackers to use a narrow channel to bypass the network14

15. Testing a Firewall Configuration15A faster and easier method is available with the Linux firewall implementation Allows you to manually generate tests

16. Suppose our local network is 172.16.1.0

17. And we allow only TCP connections Example16# ipchains -C forward -p tcp -s 172.16.1.0 1025 -d 44.136.8.2 80 -i eth0accepted# ipchains -C forward -p tcp -s 172.16.2.0 1025 -d 44.136.8.2 80 -i eth0denied# ipchains -C forward -p udp -s 172.16.1.0 1025 -d 44.136.8.2 80 -i eth0denied# ipchains -C forward -p tcp -s 172.16.1.0 1025 -d 44.136.8.2 23 -i eth0denied sourceDestinationWrongWrongWrong

18. REFRENCES17www.howstuffworks.com www.securityfocus.com www.firewall.com

19. 18Conclusion