Purpose Of Firewalls

May 4, 2014

Mr. Todd Williams

Chief Executive Officer

ALR Systems & Software

10000 California St, Suite 100

Omaha, Nebraska 68104

Dear Mr. Williams:

Firewalls are a critical portion of network security. Firewalls control traffic flow by preventing unauthorized packets from entering or exiting your network. Every packet that comes through your network is thoroughly analyzed, the firewall then decides to either send them through or reject them. When deciding what type of firewall to implement it is important that you know what your options are. There are three main types of firewalls: packet-filtering firewalls, stateful inspection firewalls, and application proxy firewalls.

Packet-filtering firewalls are the most basic of the three, essentially operating as a router. These firewalls inspect the source and destination IP address, IP header information, TCP header information, interface, as well as the TCP control flag (SYN, ACK, FIN, PSH, and RST). Packet-filtering firewalls simply use a set of rules to inspect traffic, it then decides the traffic’s fate. These firewalls are also stateless, meaning they have no memory of previous packets that they have encountered. Because packet-filtering firewalls are unaware they are more susceptible to allowing unauthorized traffic. This is why you should never rely solely on a packet-filtering firewall to block unauthorized traffic on your network. If you do decide to implement a packet-filtering firewall on your network the router would be the best place for it, for obvious reasons. Most networks today combine the packet-filtering firewall with either a stateful inspection firewall or an application proxy firewall.

Next we have stateful inspection firewalls. These types of firewal...

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... multilayered. I have provided you with a very good amount of information to assist you in your decision making process. It is now up to you to continue your research and come up with the best decision for your company.

References

Davis, C., Schiller, M., & Wheeler, K. (2011). IT auditing: Using controls to protect information assets (2nd ed.). New York: McGraw-Hill.

Kim, D., & Solomon, M. (2014). Fundamentals of information systems security (2nd ed.). Burlington,

MA: Jones & Bartlett Learning.

Qusayairi, A. (2013, August 13). Packet filtering firewalls. Retrieved May 4, 2014, from http://aeriqusyairi.com/2013/08/13/packet-filtering-firewalls/ Roeckl, C. (2004). Stateful inspection firewalls [White paper]. Retrieved May 4, 2014, from

http://www.abchost.cz/download/204-4/juniper-stateful-inspection-firewall.pdf