Network Security: Protocols, Layers, and Virtualization Analysis

This assignment delves into the intricacies of network security, examining the application, internet, and physical layers. It explores the functions of the application layer, including server-client and peer-to-peer architectures, alongside protocols like web browsing and email clients. The internet layer is discussed, focusing on the Address Resolution Protocol (ARP) and its commands. The physical layer covers multiplexing, Manchester encoding, and data flow through various transmission media. The assignment also addresses specific questions related to error control mechanisms in multipoint networks, the role of routers, and the modification of Ethernet headers. Furthermore, the assignment explores port number destinations, TCP connection processes, and virtualization products. It also touches upon mobile network generations (1G to 4G) and their technologies, including cell distribution and mobile switching centers. The assignment is a comprehensive overview of key network security concepts, providing a solid foundation for understanding the complexities of network protection.

Networking Security
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Introduction.
Network security is the process of controlling unauthorized and malicious access to a
network and the data being transmitted through the network. The malicious activities include
access to, modification and misuse of transmitted data. The process of network security
includes policies, principles, practices and activities directed towards protection of the
network. Management and control of the network is the responsibility of a network
administrator. Access to the network is controlled through user identification techniques such
as allocation of identification codes or numbers and a password. The network is divided into
different layers which share or have different network security vulnerabilities. In this topic,
the application, internet and physical layers of network security are discussed.
Application layer.
The application layer of a network allows the user to interact with the different
services that are available on the network. These services include browsing, emailing and
social networks. The applications contained in the application layer are installed into user
devices and have access to the internet through the network. Such applications also enable the
processes of network sharing which include printer sharing.
The application is categorized differently according to architecture.
The server-client architecture: the client accesses services from the server through
authentication. The client is the user of application. The server provides the services while
client acts as the consumer of the services provided.
Peer-peer architecture: the connected devices interchange information across the
network and have no defined server nor client computer. However, in this design of
application layer, either computer can act in the capacity of the server to the other connected
computer.
The application layer can be grouped further into the host-based and cloud-based
architectures.
The application layer was described using examples of the web browser and email
client. The discussion reviewed the different network protocols.

The internet layer.
The internet layer topic introduces the Address Resolution Protocol. The ARP defines
the MAC address of the connected device while on the LAN. Some commands and examples
of the ARP are discussed.
The ARP cache content can be observed through the arp-a command.
When an entry is to be deleted, the command arp-d ip is used. The ip is the true
address of the entry to be deleted.
To make deletions of all the entries, arp-d* is used.
This commands were demonstrated on Linux and the data link layer reviewed. The
network layer transmits communication from one host to the other. Ip addresses are used in
the layer in forms of ipv4 and ipv6.
Physical layer.
This layer includes multiplexing, Manchester encoding, transmission media and the
data flow comprising of analog and digital data. The physical layer forms the interconnection
in a network of all the computers and the devices.
In digital computers, data is stored and processed in digital formats in texts and
programs or other forms. Analog data can be interchanged into digital and analogue formats
during transmission. Analog data includes voice.
In the Manchester encoding, binary values are represented by the transition of the bits
in periods.
Data flow through a network is through simplex, half duplex and full duplex. Simplex
data flow involves transmission of data only on a single path in one direction. Half duplex
data flow is the transmission of data in both directions but in one direction at a time. Full
duplex allows the flow of data in both directions at the same time.
Data channels are divided into several channels to allow multiple transmission of data
sets through multiplexing. Multiplexing includes frequency division, wavelength division and
time division multiplexing.
Transmission media are physical entities of the network that transfer data from one
device to another or host to another host. The transmission media include cables such as

optical cables and coaxial cables, terrestrial microwaves, satellite microwaves and twisted
pair cables.
Question Based
Topic 4.
Question 5.
Within a multipoint network, the LCC sublayer functions in the error control
mechanisms by provision of automatic repeat requests and also provide flow control and
management. These functions are provided by the multiplexing mechanism under the LCC.
Question 7.
Routers have the ability to connect to multiple physical networks and reduce data and
network redundancy. Routers therefore, are made with multiple network interfaces cards.
Network interface cards are multiple to facilitate the router connection onto different physical
networks properly. To reduce redundancy in any case one NIC card is corrupted, the other
cards perform the functions.
Question 19.
When the internet protocol is mapped successfully to the MAC address, a new entry is
added to the Address resolution protocol. The entries are added dynamically to allow addition
of the static entries. Using the elapse of a predetermined time, the MAC address can be
removed from the address resolution protocol. This predetermined time is set up depending
on or not on the network’s disconnection status.
Question 20.
When a new address is added, the Ethernet header is modified to the router to
accommodate the new destination.

Topic 6.
Question 5.
Storing port number destinations are located from zero to 65535. Counting the
number starting from zero, one is added on to the number 65535 and therefore the number of
bits which use the storing port number destination is 65536.
Question 8.
Opening a new tab in a web browser allocates a new port on the connected computer
each time an attempt to establish connection on a network is made. The data and packet
requests made or transmitted are not modified nor interrupted because they are specifically
labelled to each port.
Question 14.
The process is carried out in three different steps.
 Client attempts a network connection to the server.
 The server gives feedback acknowledging the connection.
 The client acknowledges the server response.
Question 15.
The TCP window size field implements the flow control. The sender specifies the
maximum byte number that can be received without acknowledgement and the receiver will
delay the acknowledgement by slowing or stopping the sending of data.
Topic 8.
Question 5.
Type 1 virtualizations products occur on the firmware while type 2 products are on
the operating system.
Question 8.
1G had a frequency of 30HZ and only supported voice. 2G supported internet services
over voice, sms and mms with a switching for voice and data packets. Based on the CDMA
technology, 3G introduced high data speed.

Under 4G, LTE is based on the IP founded mainly on LTE technology. Allows very
high data rates.
Question 9.
Cells are used to distribute network over the geographical area.
Mobile switching centre manages and controls the network interfaces and telephone
services for the public.
Base station is the network’s fixed communication point.
Question 10.
The mobile switching centre allows the management and controls the shifting of user
devices from one cell to the other. After the change from a cell to another, the new traffic on
the network is directed to the base station.
References.
Wang, J. (2009). Computer network security: theory and practice. Springer Publishing
Company, Incorporated
Satkunanathan, L., Sunkammurali, K., & Watson, E. B. (2012). U.S. Patent No. 8,239,943.
Washington, DC: U.S. Patent and Trademark Office.
Choi, M. K., Robles, R. J., Hong, C. H., & Kim, T. H. (2008). Wireless network security:
Vulnerabilities, threats and countermeasures. International Journal of Multimedia and
Ubiquitous Engineering, 3(3), 77-86.
Elliot, H. A., & Elliot, D. (2009). U.S. Patent No. 7,593,512. Washington, DC: U.S. Patent
and Trademark Office.