Interestingly enough, the term “firewall” comes from a very literal place. In the 1800’s a firewall was literally a wall that was built to confine any potential fires and keep them from spreading. They were popular in urban cities and places where buildings were close together and thus were at a great risk of a fire spreading. During the industrial revolution, when cities expanded and technology flourished, it was these urban places that used the new technology the most. So in the 1980’s when computer security became an issue, it was also these urban cities that were at the most risk. The idea of confining a computer so outside disasters could not spread was based on the firewalls that were still erected in the cities. Thus, the computer firewall was born.
The first firewalls were known as “packet filter firewalls”. They worked by dividing that computer space into packets and then inspecting each packet individually. Anything incoming had to match certain rules in order to make it past a virtual wall constructed around the system. The method was slow, but effective.
Since then firewalls have advanced. Computers are more complex than ever. Almost every home in the western world has one. With so much technology available, it has always been inevitable that someone would create harmful viruses and the like, sometimes for profit and sometimes just because they can. It is just a part of human nature, unfortunately. Luckily just as there are smart people trying to destroy the system, there are other smart people trying to protect it. That is where firewalls come in. As hackers come up with more creative ways to infiltrate a system, other geniuses come up with more creative ways to stop them. In present day there are three main types of firewalls that attempt to do this.
Application Layer Firewalls: These firewalls also work on the packet system, but have become pretty advanced since the 1980’s. Application firewalls are programmed to recognize known pathogens such as Trojan horses and computer worms. There is an additional inspection layer to the packets to give them further filtering advantages.
Network Layer Firewalls: There are two sub-types of network layer firewalls; stateful and stateless. They are pretty much the same except for one major difference: stateful firewalls can be used in active sessions because they use a standard state information. Stateless firewalls are typically cheaper but also less reliable
Hardware Firewalls: The newest firewalls harkens back to the good old days of physical disaster protection. Hardware firewalls use computer hardware situated strategically in a server or computer to protect and filter information. These were invented and are manufactured by a company called Cisco. Cisco hardware firewalls are the beginning of the next generation of computer protection. They are not modeled after or resemble the old packet model in anyway. Though they are a new technology and thus have a lot of kinks to work out, they are the future of firewall protection.