Every computer needs a firewall. When we access internet the firewall must control(what information goes out and what information comes in) and protect our personal computer or internal network such as LAN.Firewall acts as a basic security system of our computer or internal network.One of the main function of firewall is to examine application or protocol that tries to establish a communication channel on our computer and everytime alart the user for takes action such as allows or block.Firewall are becoming more sophisticated day by day.A firewall provides a single point of defense between two networks .it protects one network from another.A firewall is software or hardware-based network security system that controls the incoming and outgoing network traffic by analysing the data packets and determining whether they should be allowed through or not, based on a rule set. A network's firewall builds a bridge between the internal network or computer it protects, upon securing that the other network is secure and trusted, usually an external (inter)network, such as the Internet, that is not assumed to be secure and trusted.Many personal computer operating systems include software based firewalls to protect against viruses from public network.Many router that controls packet data include firewall components.
