What is a Firewall?

A firewall is a dedicated appliance, or software running on a computer which inspects the network traffic passing through it, and denies or permits passage based on a set of rules set by the network administrator.

It is normaly placed between the protected network and the I.S.P modem and acts like a gate that protects assests to ensure nothign private goes out of the network and nothing malicous comes in.

A Firewall's basic task is to regulate some of ht eflow of traffic between computer networks of different trust levels. Typical examples are the internet which is a zone with no trust and an internal network which is a zone of higher trust. A zone with an intermediate trust level, situated between the internet and trusted internal network, is often referred to as a "perimeter network", or Demilitarized Zone (DMZ)

A firewalls's function within a network is a similiar to a physical firewall with fire doors in building construction. In the former case, it is used to prevent network intrusion to the private network. In the latter case, it is intended to contain and delay structural fire from spreading to the adjacent structures.

The History of a firewall

The term firewall / fireblock originally meant a wallto confine a fire or potential fire within a building. Later uses refer to similar structures such as the metal sheet seperating the engine compartment of a vehicle or aircraft from the passenger compartment.

Firewall technology emerged in the late 1980's wgeb tge ubrerber was a fairly new technology in terms of its global use and connectibity. The predecessors to firewalls for networks security were the routers used in the late 1980's to seperate networks from one another. The view of the internet as a relatively small community of compatiable users who valued openness for sharing and collaboration was ended by a number of major internet security breached which occurred in the late 1980's