Firewall
Hard Drive Recovery - Firewall
Firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device configured to permit, deny, encrypt, decrypt, or proxy all computer traffic between different security domains based on rules.
Firewall solutions emerged in the late 1980s when Internet was a fairly new technology. The predecessors to firewalls for network security were the routers used in the late 1980s to separate networks from one another.
Firewalls have network address translation (NAT) functionality, and the hosts protected behind a firewall commonly have addresses in the private address range, as defined in RFC 1918.
Firewalls can be implemented in either hardware or software, or a combination of both. Firewalls can be used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets.
All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria.
Firewalls have functionalities to hide the true address of protected hosts. The NAT function was developed to address the limited number of IPv4 routable addresses that could be assigned to companies and reduce the amount and therefore cost of obtaining public addresses for every computer in an enterprise.
The first paper published on firewall was in 1988 by engineers from Digital Equipment Corporation (DEC) which developed filter systems — packet filter firewalls. At AT&T Bell Labs, Bill Cheswick and Steve Bellovin, continuing their research in packet filtering, developed a working model for their own company based on the original first generation architecture.
