what is firewall ?
 

what is firewall and why it is use .

Basically, a firewall is a barrier to keep destructive forces away from your property. In fact, that's why its called a firewall. Its job is similar to a physical firewall that keeps a fire from spreading from one area to the next.
A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. If an incoming packet of information is flagged by the filters, it is not allowed through.
A firewall gives a company tremendous control over how people use the network.
Firewalls use one or more of three methods to control traffic flowing in and out of the network:
* Packet 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.

Firewall is a dedicated piece of hardware which is used to allow two networks to be communicated in a limited way. It is a system designed to prevent unauthorized access from or to a private network is known as firewall. It can be implemented in software and hardware or in combination in both as well. There are a lot of techniques used in this including packet filter, application gateway, circuit-level gateway, proxy server, etc.
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Thanks for sharing........... :D :)

Nice information thanks for sharing with us

In computing, a firewall is a software or hardware-based network security system that controls the incoming and outgoing network traffic based on applied rule set. A firewall establishes a barrier between a trusted, secure internal network and another network (e.g., the Internet) that is not assumed to be secure and trusted.

Very good information thanks for sharing.

Hi

A firewall may be a set of connected programs, placed at a network entryway server, that protects the resources of a personal network from users from alternative networks.

Its simple.. You can allow/block the incoming and outgoing network traffics by setting a rule on it... Basically its useful to protect unwanted incoming threats from the public netwok... [control panel -> windows firewall]

It block all unnecessary traffic to enter your computer.

It is nothing but a piece of a software program which exists between your PC and Internet and acts as a protective layer to get rid of threats.

A firewall may be a set of connected programs, placed at a network entryway server, that protects the resources of a personal network from users from alternative networks.