28
2008
What is a Firewall?
A firewall is a hardware device or software program which is set to limit access of data through a computer network with different levels of security for the different types of data.
There are different types of firewalls which can be employed on a single computer to a large network of computers as in the case of a large business. The firewall name has it’s roots naturally in the firewalls that you would see in large buildings which are in place to prevent, of all things fire, from entering an area or escaping from another area thus spreading the fire and spreading the damage. Firewalls in your computer or business network can act in much the same way as it trys to prevent access from a virus or some other malicious software program into a computer network or if the virus has already infected one computer or a set of computers on that network it tries to prevent that virus from spreading to other computers which are on the same network and which are protected by the same firewall.
The history of the firewall is that the technology first started to emerge in the late 1980’s when the internet was just starting to gain a foothold in terms of it’s usage across the globe and it’s connectivity. The idea originated after what is known as the Morris Worm attack happened in 1988 when a virus was spread through a number of computers which was at the time connected to the internet, then it was more of a research tool than what it has become today which is a complete medium for various capacities to interact with people around the world. The Morris Worm sparked a panic among those on the internet at the time as in 1988 an employee at the NASA Ames Research Center in California sent a memo by email to his colleagues that read; “We are currently under attack from an Internet VIRUS! It has hit Berkeley, UC San Diego, Lawrence Livermore, Stanford, and NASA Ames.” This was a new problem for the researchers working on the internet and they decided that they needed to come up with a preventative measure or measures which could deal with this type of unexpected threat.
The first generation of firewalls were known as packet filters or packet filtering which in essence looks at the packets of incoming or out going data to or from a computer and if the packet of data matches some pre-programmed set of rules for what data the firewall should look for and what data packets should therefore be dropped.
The second generation of firewalls developed in the early 1990’s became known as stateful firewalls as this type of firewall keeps records of all of the connections passing through the firewall and the stateful firewall is able to determine many things about the connection including whether it is an existing connection or a new connection. In this case the connection itself can be the trigger of the firewall which helps the firewall to prevent attacks which are exploiting existing connections.
The third generation firewall became known as the application layer firewall and the main benefit to this new generation of firewall is that in the application layer of filtering it can understand what types of applications or protocols are being used, like web browsing, FTP or DNS and it can look at those protocols and determines if anything unwanted, like a DDOS attack, is being sneaked in through one of the ports.
Firewalls have progressed steadily since their inception in 1988 and although cyber attacks still happen, many of them are thwarted by these firewalls.
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