What is firewall?

1. What is firewall? • Originally, firewall is meant a fireproof wall intended to prevent the spread of fire from one area of a building to another. • In computer security, firewall is a system designed to prevent unauthorized access to or from a private network.

2. Why you need firewall ? • Connecting to Internet without a firewall is like leaving the keys in your car with the engine running and the doors unlocked while you run into the store. • If your computer is not protected when you connect to the Internet, hackers can gain access to personal information on your computer and spread malicious code, such as viruses, worms, and Trojan Horses. • A firewall can help protect your computer against these and other security attacks.

3. Where is the firewall located ?

4. How it works ? • When you're connected to the Internet, you're sending and receiving information in small units called packets. • A packet contains the addresses of the sender and the recipient along with a piece of data, a request, a command, or almost anything having to do with your connection to the Internet. • A firewall examines each data packet sent to or from your computer to see if it meets a set of criteria. • The firewall then selectively passes or blocks the packet.

5. Types of firewall 1. Packet Filtering Firewall 2. Circuit Level Gateway 4. Stateful Multilayer Inspection Firewall 3. Application Level Gateway

6. Advantages of firewall • Concentration of security • All modified software and logging is located on the firewall system as opposed to being distributed on many hosts. • Protocol filtering • Firewall filters protocols and services that are either not necessary or that cannot be adequately secured from exploitation. • Information hiding • Firewall can “hide” names of internal systems or electronic mail addresses, thereby revealing less information to outside hosts. • Application gateways • Firewall requires inside or outside users to connect first to the firewall before connecting further, thereby filtering the protocol. • Extended logging • Firewall can concentrate extended logging of network traffic on one system. • Centralized and simplified network services management • Such as ftp, electronic mail, gopher, and other similar services are located on the firewall system(s) as opposed to being maintained on many systems.

7. Personal firewall • A piece of software that creates a protective barrier between your computer and potentially harmful content on the Internet. • Usually personal firewall has three categories of rules: • Allow - traffic that is known to be “safe”, you have defined it • Block - traffic that is known to be “problematic” or dangerous to your compute • Ask - it initially asks you whether to permit your applications to access network resources

8. Personal firewall products • http://www.tinysoftware.com/ - Tiny Software • http://www.sygate.com/ - Sygate • http://www.symantec.com/ - Symantec • http://www.kerio.com/ - Kerio • http://www.mcafee.com/ - McAfee • http://www.zonelabs.com/ - Zone Labs • http://www.agnitum.com/ - Agnitum • http://www.iss.net/ - Internet Security Systems • http://www.deerfield.com/ - Deerfield

9. Firewall on Windows XP • Microsoft Windows XP helps provide Internet security in the form of a firewall, known as the Internet Connection Firewall (ICF). • ICF is designed for home and small business use and provides protection for computers directly connected to the Internet. • You must be logged on to your computer with an administrator account in order to enable the firewall

10. Windows XP Firewall Setting • http://www.microsoft.com/windowsxp/using/networking/learnmore/icf.mspx • http://www.microsoft.com/athome/security/protect/windowsxp/firewall.aspx