Cortney Buchanan

Firewall: Packet-Filtering, Perimeter, and Internal
Why is a Firewall Important and What is it?
    A firewall is important because it helps a network stay secure by protecting the network from unauthorized users. According to Wikipedia, "a firewall can either be software-based or hardware-based." The traffic coming from and going to the Internet must pass through a firewall. As the traffic passes through, the firewall will either allow the traffic to continue or not. Firewalls are also great for scanning and blocking traffic that may contain a virus. There are many different firewall forms which include packet-filtering, perimeter, and internal firewalls. All three of these forms are used for the same purpose, but in different ways. Multiple firewalls can be used at once, which hugely decreases the chances of an unauthorized user accessing the network.  Firewalls can be used for general-purpose computers, special-purpose computers, or on routers. Firewalls can range from being simple to more sophisticated. A firewalls sole purpose is protection.

Perimeter Firewall: 
    The perimeter firewall is the firewall that is outside the network. According to the book Using MIS, “perimeter firewalls are the first device that Internet traffic encounters.” The purpose of the perimeter firewall is to protect the network by protecting all computers of an organization. So basically the perimeter sits between an organization’s Local Area Network (LAN) and the worldwide web. It is extremely important for organizations to have a perimeter firewall for the safety of the business.

Internal Firewall:
    The internal firewall main focus is on the LAN of an organization. This firewall is found between either two parts of the same organization or between two organizations that use the same LAN. The internal firewall too is extremely important to an organization and helps keep the network secure.

Packet-Filtering Firewall:
    The packet-filtering firewalls were the first type of firewall ever to be used. They are the most basic type of firewall there is. This type of firewall examines each packet that passes through and only allows those that are okay through your firewall policy. Packet-filtering firewalls look at all data in a packet before allowing it to pass or not. The other two items that it examines it the source address and the destination address to help it decide if the packet is safe or not. This type of firewall can also stop certain users from starting a session with users that are protected by the firewall.  There are ways a packet-filtering firewall can be divided, which are, stateless packet-filtering and stateful packet-filtering. In stateless packet-filtering, firewalls are found to be on the dumb side. This means they have a hard time remembering information, which can make it easy to break through.  However, stateful packet-filtering firewalls are great at remembering information and are extremely hard for an unwanted source to break through.  Just like the other two firewalls packet-filtering firewalls are very important and meant to protect users from unwanted traffic.

    Firewalls are extremely important and helpful in protecting sensitive information. Any computer that is connected to the World Wide Web should not be caught without a firewall of some sort. Also always remember the more firewalls the more protected.   

For more information on the basics of firewalls click on this link:
What is a Firewall? Watch this video...

YouTube Video

For a funny look at what a firewall does watch the video below!

YouTube Video


Kroenke, David. "Using MIS." 3rd. Upper Saddle River: NJ. Pearson 2011. 191-192.

Sharma, Ganesh. "Firewall: Same Basic Ideas." World of Security. 24 June 2010. Web: 8 May 2012.

Wikipedia. "Firewall (computing)." 9 May 2012. Web: 9 May 2012.