Firewall :- Firewall is a network device which controls the incoming and outgoing network traffic based on a applied set of rules. Basically this device is used for authentication purpose, also firewall is just like a barrier used in network. Firewall has two properties I mean we have two conditions in firewall one is Denied and another one is Permit and we can only put one condition in action in a network.
Now as you can see in the diagram there is a device between My computer and Computer A and Computer B. So if Computer A and B want to communicate with My computer they have to get authenticated after that they can communicate with My computer otherwise they are not Permitted to connect to My computer. But in case of Computer C there are no any firewall device used between My computer and Computer C so they can connect and communicate between each other without any authentication. Now I think I have clear myself about firewall. Firewall can hardware as well as a software also.
PIX and ASA are the examples of firewall hardware devices.
First Generation
Packet filter :- Firewall technology was first introduce by engineers of Digital Equipment Corporation in 1988, They developed filter system known as Packet filter firewall.This system was the first generation and now this system is known as technical Internet security. After that AT & T, Bell Labs were continuing their research in packet filtering and developed their own model.
Second Generation
Stateful filters:- Three colleagues were introduce second gen generation of firewall known as Circuit level gateways. Second generation firewall were almost same as first generation firewalls but they work on layer 4 of the OSI model.
Third Generation
Application Layer:- Application firewall is invented by Wie Xu and Peter churchyard and that was also known as Firewall tool kit.
PIX and ASA are the examples of firewall hardware devices.
First Generation
Packet filter :- Firewall technology was first introduce by engineers of Digital Equipment Corporation in 1988, They developed filter system known as Packet filter firewall.This system was the first generation and now this system is known as technical Internet security. After that AT & T, Bell Labs were continuing their research in packet filtering and developed their own model.
Second Generation
Stateful filters:- Three colleagues were introduce second gen generation of firewall known as Circuit level gateways. Second generation firewall were almost same as first generation firewalls but they work on layer 4 of the OSI model.
Third Generation
Application Layer:- Application firewall is invented by Wie Xu and Peter churchyard and that was also known as Firewall tool kit.
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