FIREWALLS By k.shivakumar 08k81f0025

CONTENTS Introduction. What is firewall? Hardware vs. software firewalls. Working of a software firewalls. Firewall rules. Ability and disability. Considerations. Examples of firewall software's. Firewall in windows xp. Protection methods. Conclusion.

INTRODUCTION With the large number of firewall solutions available today, firewall selection and implementation can be a time-consuming and overwhelming process. The appealing manner in which "firewall" solutions are marketed, along with claims of easy installation and management, can lead organizations to make the decision to implement a firewall solution without taking time to thoroughly examine the need for one. By making hasty decisions, organizations can overlook the impact a firewall solution can have on their existing network and users

What is a Firewall? A firewall is 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. Sits between two networks Used to protect one from the other Places a bottleneck between the networks

Hardware vs. Software Firewalls Hardware Firewalls Protect an entire network Implemented on the router level Usually more expensive, harder to configure Software Firewalls Protect a single computer Usually less expensive, easier to configure

How does a software firewall work? Inspects each individual “packet” of data as it arrives at either side of the firewall Inbound to or outbound from your computer Determines whether it should be allowed to pass through or if it should be blocked

Firewall Rules Allow – traffic that flows automatically because it has been deemed as “safe”. 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

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

What a personal firewall cannot do Cannot prevent viruses Only an antivirus product with updated definitions can prevent viruses After setting it initially, you can forget about it The firewall will require periodic updates to the rulesets and the software itself

Considerations when using personal firewall software If you did not initialize an action and your firewall picks up something, you should most likely deny it and investigate it If you notice you cannot do something you did prior to the installation, there is a good chance it might be because of your firewall

Examples of personal firewall software ZoneAlarm BlackICE Defender Tiny Personal Firewall Norton Personal Firewall ***Please be sure to read the license agreement carefully to verify that the firewall can be legally used at home and/or the office.

Windows XP Firewall Currently *not* enabled by default Enable under Start -> Settings -> Control Panel Select Local Area Connection Select the Properties button Click the “Advanced” tab

Windows XP firewall

Updates to Windows XP Firewall *Will* be enabled in default installations of Windows XP Service Pack 2 Ports will be closed except when they are in use Improved user interface for easier configuration Improved application compatibility when firewall is enabled

PROTECTION METHODS Packet filtering. Network address translation. Proxy services.

Packet filters Compare network and transport protocols to a database of rules and then forward only the packets that meet the criteria of the rules Packet filtering is a screening method i.e. used in network and transport layer of OSI reference model. Implemented in routers and sometimes in the TCP/IP stacks of workstation machines in a router a filter prevents suspicious packets from reaching your network

Network Address Translation. Translates the addresses of internal hosts so as to hide them from the outside world Single host makes requests on behalf of all internal users hides the internal users behind the NAT’s IP address internal users can have any IP address should use the reserved ranges of n.m or 10.n.m.p to avoid possible conflicts with duplicate external addresses

proxies Hides internal users from the external network by hiding them behind the IP of the proxy proxy is a combination of a client and a server; internal users send requests to the server portion of the proxy which then sends the internal users requests out through its client ( keeps track of which users requested what, do redirect returned data back to appropriate user) Address seen by the external network is the address of the proxy

CONCLUSION Using firewall we can protect our pc’s from unauthorized user. Make our programs compatible & secure. When choosing and implementing a firewall solution, do the homework and make a decision based on the organization's needs, security policy, technical analysis, and financial resources.

QUESTIONS?