Fire-wall

Outlines: Firewall concept. Fire-wall rule. Types of fire-wall. How fire-wall works? Using more than one firewall on a computer. Fire-wall vs. Antivirus. SUMMARY.

What is firewall? A firewall is software or hardware that checks information coming from the Internet or a network, and then either blocks it or allows it to pass through to your computer, depending on your firewall settings.

Why do I need a fire-wall ? A firewall can help prevent hackers or malicious software (such as worms) from gaining access to your computer through a network or the Internet. A firewall can also help stop your computer from sending malicious software to other computers.

Why do I need a fire-wall ?..(cont) Even if you think there is nothing on your computer that would interest anyone, a worm could completely disable your computer, or someone could use your computer to help spread worms or viruses to other computers without your knowledge.

Is their another things fire-wall can't prevent? YES, They are: 1- E‑mail viruses . 2- Phishing scams .

Types of fire-wall: 1- personal firewall: In the home, a personal firewall typically comes with or is installed in the user's computer . Personal firewalls may also detect outbound traffic to guard against spyware, which could be sending your surfing habits to a Web site.

2-Organization fire-wall: In the organization, a firewall can be : a stand-alone machine. software in a router server. Combination of routers & servers.

Can I use more than one firewall on my computer? Yes, but running more than one firewall program at the same time could cause conflicts. It's best to just use one firewall program.

How fire-wall work?? Firewalls use one or more of three methods to control traffic flowing in and out of the network: Packet filtering. Proxy service. Stateful inspection.

Packets filtering Packets (small chunks of data) are analyzed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.

Proxy service Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

Stateful inspection - A newer method that doesn't examine the contents of each packet but instead compares certain key parts of the packet to a database of trusted information. Information traveling from inside the firewall to the outside is monitored for specific defining characteristics, then incoming information is compared to these characteristics. If the comparison yields a reasonable match, the information is allowed through. Otherwise it is discarded.

Fire-wall vs. antivirus Firewall protection will stop hackers from getting into your computer or network, and so will stop viruses as well. Antivirus software protects computers from viruses and other malware, such as Trojans, worms and keyloggers. However you can pick up a virus in different ways such as from a CD or USB, from another computer on the network, etc

Summary Firewall is a piece of software that creates a barrier between Internet and your PC. Fire-wall control the traffic that goes from and to your computer and blocks such packets. Personal & organization fire-wall. One fire-wall software is enough in PC. Antivirus work with viruses & fire-wall control the traffic.

Reference: A History and Survey of Network Firewalls KENNETH INGHAM Kenneth Ingham Consulting and STEPHANIE FORREST www. ITSecurtiy.com

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