Computer Science: Database programming

Questions
1. Discuss the importance of data models.  
2. What is a business rule, and what is its purpose in data modeling?
3. What languages emerged to standardize the basic network data model, and why was such standardization important to users and designers?
4. Describe the basic features of the relational data model and discuss their importance to the end user and the designer.
5. Explain how the entity-relationship (ER) model helped produce a more structured relational database design environment.
6. Consider the scenario described by the statement “A customer can make many payments, but each payment is made by only one customer.” Use this scenario as the basis for an entity relationship diagram (ERD) representation.
7. Why is an object said to have greater semantic content than an entity?
8. What is the difference between an object and a class in the object-oriented data model (OODM)?
9. How would you model Question 7 with an OODM? (Use Figure 2.4 as your guide.)

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Network security monitoring

Questions

1. In the network diagram above, select one of the letters as the location to place your only IDS sensor. Explain why it is better than the other 3 locations.
Create a snort rule to detect the word monkey in ICMP packets leaving your home network of 10.10.0.0/16.
2. Your colleague was asked to write a snort rule to detect connections over port 80 coming from the internal network and going to a specific external host (8.8.4.4). His rule isn't work right. What is the problem? (Note: $HOME_NET is properly defined in this instance of snort.)
alert tcp $8.8.4.4 80 <­ $HOME_NET any (msg:"Port 80 connect to 8.8.4.4"; sid:1000002; rev:2;)
3.Your colleague was asked to write a snort rule to detect tcp traffic from the internet containing the word layoff. You aren't surprised when it doesn't work, because this is the second time he's asked you for help during this final. You take a look at the rule. Why doesn't it work?
alert tcp $EXTERNAL_NET ­> $HOME_NET any (msg:"Layoff message detected!"; content: "|layoff|"; sid:1000003; rev:1;)
4. A new botnet named Honeyshark has emerged. You have been instructed to write a Snort rule to look for the command and control channel that uses IRC over port 6667, 6668, and 6670. Write a rule to detect Honeyshark command and control connections.
5. A new bit of malware called Honeymonkey has emerged. It is interesting in the fact it uses ICMP echo reply and DNS over UDP to transfer data. Messages always contain the hex DE AD BE EF regardless of protocols.
Create one or two rules that will specifically catch this information.
5. You suspect your coworker Andy is planning something nefarious. Another coworker suggests setting up IDS rules to monitor for key words to catch Andy's internet searches. What is the flaw in this plan?
6. After a particularly nasty distributed denial of service attack, all IT staff are invited to a conference call to discuss network changes. The security intern notes that he has captured all the IP address, MAC addresses, and port numbers from the attack. He suggest blocking the source MAC address as this would block the most attackers. You spit Mountain Dew all over your monitor and unmute your phone. What are you going to say?

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General Cloud Environment

General Cloud Environment

Introduction

Cloud computing refers to the storing and accessing data and programs over the internet rather than on the computer’s hard drive (Badger, Grance, Patt-Corner & Voas, 2012). It is the delivery of computing services over the internet and allowing network access to computing resources, webmail, social networking sites, online file storage and online businesses, shared by a group of people. Cloud computing provides a common and shared pool of resources such as corporate and user applications, networks, and storage space. Many organizations are adopting the computing technology as a way of providing network-computing resources to their customers over a network.  

Through cloud computing, an organization can get access to on-demand self-service computing capabilities like network storage and server time whenever they need. There is also access to resources based on different platforms such as personal digital assistants (PDAs), on their laptops or mobile phones through broad network access. The computing resources from the provider are pooled to be able to serve various consumers through a multi-tenant model. In this approach, consumers are assigned and reassigned different virtual and physical resources. The allocation of resources is according to their demand where they are advised to specify the institution or data center from which they request resources since they are not in control of the virtual machines providing the resources.

The consumer can also access cloud capabilities instantly and elastically therefore allowing them to control the services. Cloud systems are capable of optimizing and controlling resources by measured service capacity and thus ideal for controlling and monitoring usage of resources hence assuring transparency for both the subscriber and provider (Badger, Grance, Patt-Corner & Voas, 2012). By pooling the computing resources, a public deployment model is, therefore, applicable where the cloud computing infrastructure is available to a large number of consumers as well as the large organizations.

Terms of Services

The consumer and the provider have a legally binding agreement that defines terms of service for a cloud infrastructure categorized into two parts. First is the service agreement that is a document that establishes the rules and regulations of the contract between the subscriber and the cloud service provider. Secondly, the agreement also involves a paper outlining the promises to the consumer regarding technical performance as well as how to solve possible performance failures (Badger, Grance, Patt-Corner & Voas, 2012). This agreement is, therefore, advantageous to a public cloud deployment model as it assures the customer of the privacy and security of information from the provider.

An organization can use service agreements among its units to align the services provided by an organization with its goals and objectives. Although, small scale users or individuals are forced to accept the terms as given by the provider, large-scale consumers with the heavy use of cloud resources can negotiate for favorable terms.  The users in a public cloud scenario have an advantage of enjoying efficient services at affordable prices. The service agreements can terminate on different occasions. Failure to pay on time by the subscriber, violation of cloud policies or for no reason. Therefore, it is important for consumers in a public cloud to understand the data retention and termination policies as defined by the provider.

Promises

It is necessary for subscribers of Public cloud to analyze and understand how providers calculate the uptime percentages when advertising the availability of their cloud resources. On failure to fulfill the promised availability, providers should offer compensation in terms of service credit that are determined by the time the service was not available during a billing period. Consumers of public cloud model should also understand the legal care of their personal information and data preservation policies as defined by the provider (Badger, Grance, Patt-Corner & Voas, 2012). Providers may not be accountable for failures resulting from natural occurrences of an even scheduled service outage. Providers may also change the terms of service agreement such as pricing after notifying the consumer.

Mobile Phones and Cloud Computing

Web-based applications on cloud computing have become a buzz word in the technological sector.  As such, it poses an interesting area of research and discussion. Mobile phones have proliferated the modern society, and they are potential benefits for addressing the digital divide (Analysis of Smartphone Security Problem - Android and iPhone, 2013). Digital divide is evident in marginalized and rural areas. Today’s mobile phones have evolved from simply being devices of sending mere texts and making calls to more sophisticated, computerized smartphones. However, despite this multi-purpose capability, mobile phones are still faced with various challenges of space, battery life and computational capabilities. Cloud computing has the potential of transforming the whole IT industry. The dedication of this research aims at exploring whether it is possible to increase the computational power and speed of mobile phones through offloading heavy application functions. 

Data Communication: Network and Transport Layers

Data Communication: Network and Transport Layers

In data communication, effective communication is only achieved when data, is successfully moved from the one destination to the other. The transport and the network layers are responsible for moving data from one end of the network to the other. The two layers mainly overlap which is a major reason they are analyzed and discussed together. The paper addresses the functions of the transport layer and the network layer. There are three functions of the transport layer that include; segmenting, session management and linking the application layer to the network layer. On the other hand, the network layer has two primary functionalities; routing and addressing. The transport and network layer protocols specify certain protocols that determine how the packets are to be organized. However, the transmission control protocol (TCP) also known as the internet protocol (IP) takes prevalence where the network and transport layers are concerned.

The transport layer provides a link between the application layer and the network layer. In addition to this, the layer is also responsible for the end-end delivery of messages. On one end, the transport layer accepts application layer outgoing messages. Some of the messages that the transport layer accepts in this regard are emailing and web data. Once the messages are received, they are segmented for transmission. The protocol data unit in this layer responsible for the segmentation is called a segment. Once the messages are segmented, they are handled over to the network layer. Here the network layer routes the messages through the network by determining the best possible route from the source to the required destination. There are a number of variables that the network layer considers prior to choosing a route. The chosen route happens to be the best approach to be adopted by the packets. An IP is appended to the message before being routed, and the packet is passed to the data link link. Here, the layers add a frame known as the Ethernet frame and instructs the physical layer on when to transmit the data.

Both the network and transport layers accept incoming messages from the data link layers and organize them coherently before passing them to the application layer. The process of message transfer is a coordination where the transport layer breaks the message into segments, passes the segments to the Network layer for routing, which in turn passes the data to the data link layer for transmission. As previously stated, the transport layer is also responsible for addressing and routing by the network layer. However, there exists a coordination between the two layers as will be evaluated in this paper. To achieve these functionalities, there are a number of protocols prevalent in the two layers. Of all the protocols, one emerges as dominant among them; the TCP/IP.

The transmission control protocol or the internet protocol (TCP/IP) was originally developed for the department of defense in the United States. However, the layer is currently the most popular protocol in the world and as such it is used on the Internet. There is an efficient transmission of data using this protocol as it enhances error-free transmissions, performs error checking and handles large files for sending across unreliable networks with a high guarantee of a low rate of data corruption. Another popularity of the link emanates from the compatibility of the protocol with data link protocols. The layer has two parts, and one part is on the transport (TCP) that links the application layer to the network layer. The layer is responsible for performing segmentation where the data is broken into segments. The segments are then numbered and transmitted to the destination which a high rate of reliability. Once the segments reach the destination, they are properly ordered to provide a coherent meaning that corresponds with the initial meaning of the transmitted message. The other part is the IP that is the network layer protocol responsible for addressing and routing functions. For all the computers through which the message passes, an IP is used. The IP is responsible for routing the message to the desired destination. TCP only plays a role when the data enters or leaves the application layer. For this reason, the software only needs to be active at the sender and receiver side.

A TCP comprises of 24 bytes of information control. The source and destination ports are defined in the header information. The defined destination port is responsible for specifying to the TCP, which application layer the packet should be sent. The source port, on the other hand, is responsible for specifying the origin of the packet. There is a sequence number that is associated with the TCP that enables the destination to reassemble the packets in the correct order and ensure that there are no lost segments. Another form of transport layer protocols present is the User Datagram Protocol (UDP) that sends message segments inform of datagrams. The protocol is commonly used where there is the need to send a single small packet. The protocol eliminates the need of the TCP to segment the packet and reassemble them on receipt. There are four fields present in a UDP and additional source and destination ports and the application layer packet. As opposed to the TCP, UDP does not check for lost datagrams, and it is for this reason that the protocol is rarely used. However, the decision regarding what protocol to use is left to the application programming engineer.

The IP is present at the network layer, and the PDUs present at the network layer are known as packets. There are two version of IP in use; the IP version 4 and the IP version 6. The former is an older version that is characterized by the presence of 24 bytes. It contains the source and destination, the packet number, and the packet length. Due to the increase in the communication devices, the IPv4 is being dropped in favor of the most robust IPv6. The latter is characterized by 40 bytes and offers a more increased address size from the initial 32 bits to 128 bits. In addition to this, IPv6 offers a simpler addressing and routing approach that enhances a variety of new, more stable approaches to routing and addressing.

The transport layer has a variety of functions among them linking to the application layer, segmenting and management of sessions. With every computer having a unique port address, it becomes easy for the transport layer to identify the source and destination of the packets as provided by their respective computers. In segmenting, TCP ensures that large volumes of messages are transmitted in the form of segments that are broken down and relied on different routes and later reassembled at the destination. The protocol oversees that all the segments are received on the receiving end. However, a major challenge facing this protocol is determining the size of the segments. It is commonly to have messages being broken down into varying segment sizes. Session management involves establishing a link and retaining the link during the communication of the networked devices. There are two approaches to managing sessions that are; connection-oriented and connectionless messaging approach.

In conclusion, there are three different types of addresses present in computers. The application layer address, the data link layer address and the network layer address. Data link layer address are part of the hardware while the network layer and application layer addresses are set by the software. The process of translating n application layer address to a network address or a network address to a data link layer address is known as address resolution. The domain name server is responsible for address resolution on receiving a special message.

Programming Essay

Proper, conspicuous and professional design is an art and not a science. The essence of developing an effective program lies not only in the need to meet the user interface requirements, but also on the need to enhance efficiency and achieve effectiveness. Therefore, prior to embarking on programming design, it is paramount to grasp the design principles (Brooks, n.d.). Functional and non-functional attributes of a program are highly influenced by its design. The fundamental reason of inculcating design principles is to reduce the cost of development.

In the development life cycle of a software, the design is a phase that is of crucial importance as it stipulates the direction to be followed by the software development. It is the design phase of programming that brings out the craftsmanship in the field. Artists aim at keeping things simple and straight forward. One of the basic rules of design is keeping things simple and stupid (KISS). Avoiding complexity and sticking to simplicity is the key to efficient design. In addition to this, the abstraction principle further supports the art of programming as an art since significant pieces of program functionality are only implemented once. Artistically, an element should not consist of unwanted elements that are not required. In a similar manner, programming design principles propagate that one should avoid adding unwanted functionality in a system. In a nutshell, the application of design principles enhances the elimination of redundancy as they offer advice on the need to eliminate unwanted repetition (Brooks, n.d.).

Lastly, the open-closed principle rules that the entities in the system such as classes, functions and modules be open for extension but closed for modification. The policy provides an adequate similarity with art since a masterpiece work of art has only one author and cannot be replicated (Brooks, n.d.). If programming were implemented as a science and not an art, then reuse of code would not be promoted. However, the proper design promotes code reuse which saves time and cost significantly and enables the construction of robust systems. For these reasons, the design serves as the key to making shorter programs.

References

Brooks, F. The mythical man-month.

comprehensive archive and document management program

Paper Requirements

You have been hired by a government agency to develop a comprehensive archive and document management program for them. The organization has over 2000 employees and operates in over 20 different location across the country. Currently, the organization maintains it records using a paper-based record management system. In recent year, the amount of documents they store is getting bigger and bigger. This has led to the loss of valuable records and it is taking long for the staff to locate and retrieve records in a timely manner. The organization is considering upgrading their paper-based record management system to an electronic record management system but are not sure what to do.
They need your advice on how to improve their recordkeeping management system. At the end of your assignment period, you are required to produce a Report containing the following three sections:
1.    A proposed Archive Policy. The section should including the following:
o Mission statement 
o Roles and responsibilities of the agency and its employees. Focus on the public right to access records; protection of the records from both confidentiality and security perspective. The roles and responsibilities must be curried out under the Federal Law No (7) of 2008.
o Training requirements

o Draft of a Legal and ethical Policy that the organization can adopt. o Any other relevant policy elements as you see fit.
2. Digital Recordkeeping Strategy. The section should including the following:
o Recommend a digital recordkeeping strategy that you think would suit the organization. Justify your recommendation by showing the advantages of implementing the strategy you suggest.
o Discuss the possible disadvantages/challenges of implementing the suggested strategy.
3. Digital Record Management System. The section should including the following:
o Assuming that the organization would like to invest in a digital record keeping system; list and describe the basic components of a commercial digital record management system and archival program.

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