This question is based on material from chapter 6. a) Discuss firewalls and explicitly explain the different ways firewalls are categorized. For each category, discuss the different methods firewalls can be defined. (15 points) b) Which firewall would you choose to use at XYZ UNIVERSITY? Explain why. (15 points) This question can be answered from chapter 8. a) Discuss and explain the following ciphers: substitution cipher, transposition cipher, exclusive or vernam cipher and Book or running key cipher. (20 points) b) Which cipher would you recommend using at XYZ UNIVERSITY? Explain why. (15 points) . This question can be answered from chapter 10. Discuss the various conversion strategies that one can implement to create a new system from an existing one.(20 points) Suppose the first project was developed in the United States and the conversion is to take place in a different country with a different culture. Explain how and if your choice of conversion strategies are affected by differences in culture. (15 points)

a) Firewalls are essential components of network security that act as a barrier between internal and external networks. They play a crucial role in preventing unauthorized access, protecting sensitive data, and ensuring the integrity of network resources. Firewalls can be categorized based on various criteria, including their structure, functionality, and filtering mechanism.

One way to categorize firewalls is based on their structure. There are two main types: hardware firewalls and software firewalls. Hardware firewalls are physical devices that are separate from the computer or the network they protect. They are often integrated into routers or network appliances and provide an extra layer of security at the network perimeter. On the other hand, software firewalls are installed on individual computers or servers and provide protection at the host level. They can be more customizable and offer granular control over traffic, but are limited by the resources of the device they are installed on.

Another way to categorize firewalls is based on their functionality. There are three main types: packet-filtering firewalls, stateful inspection firewalls, and application-layer firewalls. Packet-filtering firewalls analyze packets at the network layer (Layer 3) and make filtering decisions based on information such as source and destination IP addresses, port numbers, and protocol types. They are fast and efficient but do not inspect the content of packets. Stateful inspection firewalls, also known as dynamic packet-filtering firewalls, keep track of the state of network connections and base their filtering decisions on the context of each connection. They offer better protection against advanced attacks but may introduce latency due to maintaining connection information. Application-layer firewalls operate at the application layer (Layer 7) of the OSI model and can make filtering decisions based on specific application protocols. They provide the highest level of control and security but can be resource-intensive and complex to configure.

Furthermore, firewalls can also be categorized based on their filtering mechanism. Some common methods include blacklisting and whitelisting. Blacklisting involves creating a list of known malicious entities, such as IP addresses, domain names, or keywords, and blocking or restricting access to them. Whitelisting, on the other hand, allows only specific entities to access the network by creating a list of trusted entities. It provides a more restrictive approach but may require frequent updates and can be challenging to maintain.

In summary, firewalls can be categorized based on their structure (hardware or software), functionality (packet-filtering, stateful inspection, or application-layer), and filtering mechanism (blacklisting or whitelisting). The choice of firewall category depends on the specific requirements, resources, and security needs of the organization or network.

b) For XYZ UNIVERSITY, I would recommend using a hardware firewall with stateful inspection functionality. As a university, XYZ likely has a large network with multiple users and diverse applications. A hardware firewall would provide centralized protection and control at the network perimeter, ensuring the security of the entire network. The stateful inspection functionality would allow the firewall to analyze the context of network connections and make informed filtering decisions. This would help prevent sophisticated attacks, such as session hijacking or spoofing, while minimizing latency. Additionally, a hardware firewall would offload the security processing from individual computers or servers, allowing them to focus on their intended tasks.