Security and Firewall

A firewall is an information technology (IT) security device which is configured to permit, deny or proxy data connections set and configured by the organization's security policy. Firewalls can either be hardware and/or software based. more...

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A firewall's basic task is to control traffic between computer networks with different zones of trust. Typical examples are the Internet which is a zone with no trust and an internal network which is (and should be) a zone with high trust. The ultimate goal is to provide controlled interfaces between zones of differing trust levels through the enforcement of a security policy and connectivity model based on the least privilege principle and separation of duties.

A firewall is also called a Border Protection Device (BPD) in certain military contexts where a firewall separates networks by creating perimeter networks in a Demilitarized zone (DMZ). In a BSD context they are also known as a packet filter. A firewall's function is analogous to firewalls in building construction.

Proper configuration of firewalls demands skill from the firewall administrator. It requires considerable understanding of network protocols and of computer security. Small mistakes can render a firewall worthless as a security tool.

History

Firewall technology emerged in the late 1980s when the Internet was a fairly new technology in terms of its global use and connectivity. The original idea was formed in response to a number of major internet security breaches, which occurred in the late 1980s. In 1988 an employee at the NASA Ames Research Center in California sent a memo by email to his colleagues that read,

This virus known as the Morris Worm was carried by e-mail. The Morris Worm was the first large scale attack on Internet security; the online community was neither expecting an attack nor prepared to deal with one.

First generation - packet filters

The first paper published on firewall technology was in 1988, when Jeff Mogul from Digital Equipment Corporation (DEC) developed filter systems known as packet filter firewalls. This fairly basic system was the first generation of what would become a highly evolved and technical internet security feature. At AT&T Bill Cheswick and Steve Bellovin were continuing their research in packet filtering and developed a working model for their own company based upon their original first generation architecture.

Second generation - circuit level

From 1980-1990 two colleagues from AT&T Bell Laboratories, Dave Presetto and Howard Trickey, developed the second generation of firewalls known as circuit level firewalls.

Third generation - application layer

Publications by Gene Spafford of Purdue University, Bill Cheswick at AT&T Laboratories and Marcus Ranum described a third generation firewall known as application layer firewall, also known as proxy based firewalls. Marcus Ranum's work on the technology spearheaded the creation of the first commercial product. The product was released by DEC who named it the SEAL product. DEC’s first major sale was on June 13, 1991 to a chemical company based on the East Coast of the USA.

Read more at Wikipedia.org