A “firewall” is an over-arching term to describe a specialized security system for a computer network. It is an operating system based designed software to control and protect the computer from unauthorized contents. Main feature of computer firewall is to prevent unwanted contents. It has predefined rules to access the computer. It is a device or set of devices are used to permit, deny, and encrypt all computer instructions based on set of rules and security criteria.
Computer firewall is the firewall software used by many users who are working on Microsoft windows. They can easily access this firewall program. This firewall acts quickly to prevent Trojans and blocks the access of the network. This blocking technique is possible when the application criteria changed.
In the 1980s the first firewall program was launched. At that time internet had not reached the people. After internet launched routers were used for computer protection and for network security.
The growth of the internet has brought in to the introduction of many firewall applications, each one having different features. Windows firewall is an application offered for free with the purchase of Windows OS.
Firewall software is working on the basis of set of rules and instructions. Optimized analysis mainly depends on the changes in settings for security protection. All these are configured and worked for system protection.
The functions of a Computer firewall are classified into three generation sets. All three functions are necessary to provide online and offline support. These generation sets control the installation, copying and sharing of a file.
The first developed filter system which is known as “packet filter”. It is first generation firewall which was worked on data transfer from the networks. The second generation firewall which is known as “stateful filter”, this firewall maintains records of all connections passing through the firewall.
The third function is a proxy based application layer firewall. This detects the applications and protocols sneaking in, through the non standard ports. Harmful and abused protocols are also blocked.
Application layer-firewalls works on the application level of the TCP/IP stack. And it will intercept all packets traveling to or from an application. Firewalls are used to search unwanted outside traffic from computer. Firewalls will prevent outright the spread of worms and Trojans.