Network Systems: Client-Server Model and Process Report

This report, created for a network analyst training program, delves into the core concepts of client-server environments. It begins by defining the roles of clients and servers, explaining their communication and the client-server model's significance. The report then explores processes, defining Process ID (PID), Parent Process ID (PPID), and the 'init' process, with a comparison of child and parent processes. The report also provides an overview of Linux server configurations, including UDP and TCP systems. The report concludes with a discussion of these topics and provides a bibliography for further reading.

MARKETING AND STRATEGIC RESOURCE MANAGEMENT
Name Your name
Task 1
Select an organisation with which you are familiar and assume that you are the
marketing executive of the organisation.
Your organisation is considering launching a new product/service, and the marketing
manager has asked you to deliver a presentation to the board. Your presentation must
show how the new product or service aligns with the current business strategy.
Word count 1500
Date 6th June 2016
Marketing and Strategic Resource Management
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Assignment 1

Contents
1. Server, Clients and Processes..................................................................................................................3
1.1 Client.....................................................................................................................................................3
1.2 Server....................................................................................................................................................3
1.3 Client server model relation..................................................................................................................4
1.4 Processes...............................................................................................................................................5
1.4.1 Child process.......................................................................................................................................5
1.4.2 Parent process....................................................................................................................................5
1.4.3 Comparison between child and parent process.................................................................................5
2. Linux server configurations......................................................................................................................6
2.1 UDP and TCP systems............................................................................................................................7
3. Conclusion...............................................................................................................................................7
4. Bibliography.............................................................................................................................................9
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Assignment 2

1. Server, Clients and Processes
The relationship between a server and a client is unique. The server, client and the host are all
configured together in a network environment. The possibilities of activities that can be performed using
the server and client model is endless. The internet is one great example of the client server model. The
client server model is one of the primary concepts that are applied in local area networks or LAN. The
following sections define the client, server and the host as individual components.
1.1 Client
The client is a piece of computer hardware or a software that can be used to gain access to a
service that is made available by a particular server. This server can be made on the same computer but
is generally hosted on a separate computer. The client can be thought as the receiving end of some
service that is provided by a server in a client/server model. The clients in almost all cases are located in
separate computers that can be accessed through a network. The client term was first used for devices
that could not run their own programs and needed remote computers to run the programs via a network.
The client is divided into three categories:
1. Thin client: This is a type of client application with the lowest number of functions possible and utilizes
resources that is provided by a host. The main function of this client is to display the results that are
obtained from the server. This type of client totally relies on the server for most of the processing tasks.
2. Thick client: This is the exact opposite of the thin client. This client can handle almost all of the
processing and is not dependent on the main server. The only connection this client requires with the
server is for uploading or updating of data or the program. The primary example of this type of client is the
antivirus software which connect to the main server only for updating itself or its definition database.
3. Hybrid: This type of client is a hybrid between the first two types. This client can do most of the
processes itself but needs the connection to a main server to transfer or store critical data.
1.2 Server
A server is a computer that is exclusively used for running services that help in serving the needs
of other computers. Based on the service that is run or maintained by the server, a server can be a
database server, print server, home media server or web server. The server is basically a program or
device that is generally used to provide services to other computers and users which are also known as
the clients. The computer that runs the server program is called as a server machines. This computer can
either be exclusively used for running the server or it may host other programs also. In the client/server
model, a server programs main function is to complete the client’s requests. The client may be running on
the same computer or different computers. There are applications available which run both as a client and
a server. They process requests from other programs and also send requests to other servers.
The different types of servers that can be configured as used are:
1. Web server: This type of server mainly deals in HTML pages or files. The web browser is a client for
this type of server.
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Assignment 3

2. Proxy server: The proxy server is an application that serves as an intermediate server between one
server and an endpoint device. The other server’s service may be requested by a user or client.
3. Mail server: A mail server is a software which is designed to receive emails from users and other
remote senders. Its job is to process these incoming email requests and forward them to their destination.
4. Blade server: This type of server contains multiple different servers which are made up of modular and
thin electric circuit boards which are known as server blades. Each individual server blade can be used
for a separate application.
5. File server: This server is used for storing and management of all data files centrally. This server can
be accessed by computers having network connectivity.
6. Application server: This server is a program which is used in a distributed network which helps in
providing business logic for a program.
1.3 Client server model relation
The client and the server are interconnected to each other. The server can be located either
inside or outside of the LAN or WAN system. The access to the server is determined by the IP address
the server has. It can be either a private IP address or public. A public IP address allows the users to
access the server via the internet, while a private IP address only allows access to the server from inside
the LAN. The data transfer speed that a client has to transfer data is totally dependent on the amount of
bandwidth needed for the transfer. A server which is LAN based will have a transfer speed decided by the
router. The faster the router, the faster the data transfer speed in a LAN based server/client model.
Similar type of logic also applies to WAN or the internet. The speed of a web page loading depends on a
number of different factors like the size of the page and the bandwidth allowed by the ISP.
The client server model is in reality a framework for communication which is distributed in nature.
The framework consists of multiple network processes among many other clients, service requesters and
service providers. The server-client connection is set up with the help of an internet or network
connection. The client-server model is an extremely important and core concept of networking. This is the
basic foundation on which the web or database servers and the email servers are developed and run on.
The main protocols and web technologies that are developed around the framework of the client-server
model are:
1. Domain Name System (DNS)
2. Telnet
3. Simple Mail Transfer Protocol (SMTP)
4. Hypertext Transfer Protocol (HTTP)
The client side include applications like chat applications, email software and web browsers. The
server side include systems like database application, chat and email application and web database
servers. The client server models is different from a peer to peer or P2P model in the respect that the P2P
model follows the concept of decentralized networking structure while the client server model follows the
centralized networking model. In the client-server model the communicating systems are either the server
or the client and both of these components have equal responsibilities and standards. The only problem
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Assignment 4

of this model is that too many requests from different clients can result in improper functioning or full
shutdown due to heavy load on the server.
1.4 Processes
A process can be defined as a case of the application that is running in a system. It is similar in
meaning when compared to an activity in some of the operating systems. In the operating system UNIX
and a few more, a process starts as soon as a program is started. This program can either be started
automatically by a different program running on that machine or manually by using a shell command.
Similar to an activity, the process is like an ongoing process with a separate group of data values that is
exclusive to the process mentioned above. This data could be used to keep track of the process. For
example, an application or software that is being used by many users through sharing must have at least
a single process running at some stage of the program’s execution for each of the users using the
application.
A process can be used to start sub processes which are also known as child process. The main
initiating process then becomes the parent process. A child process is a replica of the parent process and
uses shared resources from its parent. This process is totally dependent on the parent process and will
cease to exist if the parent process is shutdown. The processes are able to exchange data with each
other and also synchronize the different operations they perform through the use of many different ways
of the inter-process communication or the IPC.
1.4.1 Child process
A child process is generated by the parent process or the main process. A child process is
generated to do some operations that is decide by the main process. There can be multiple child
processes from a parent process but their can only be one parent or main process. Most of the attributes
of the parent process is inherited by the child process. A process with no parent is assumed to be created
by the program kernel. In the UNIX or Linux operating systems, the first process named “init” is created by
the main kernel of the program at the computer’s boot time and can never be shut down or terminated
until the system is shutdown itself. The kernel may create and launch other processes without any parent
to perform daemon tasks. A child process can become orphaned if for some reason its parent process is
killed or dies. This orphaned process is then adopted by the init process. In the UNIX operating system, a
child process in generally created using the fork system call and is a replica of the parent process. Both
the parent and the child process runs normally after forking and performs their own tasks. During the
creation process of parent or child process, each process is given a unique identification process number.
When a child process is terminated, its process ID and the resources used by the process are
automatically released.
1.4.2 Parent process
The parent processes is the process which uses the fork () system call to generate child
processes. This parent process is not the process which is created during the startup of the system. That
is the main process. To explain for clearly, a process which creates a child process is the parent process.
On the successful execution of the fork () system call, the existing process ID or PID of the child process
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Assignment 5

is sent back to the parent process and the child process is returned a 0. When the call fails to execute,
the parent process is sent a value of -1 and no child process is created.
1.4.3 Comparison between child and parent process
The child and parent processes are used in a program when multiple tasks are needed to be
done by the same process. This can be effectively used to divide larger tasks into smaller tasks where
each smaller task is handled by a separate child process. This technique helps in executing complex
multilevel programs but consumes more time and resources. For example, consider a simple program
where we need to calculate the sum of both the even and the odd numbers from a given range of
numbers. In this program instead of running two different programs, a child process can be created which
would help in calculating the subtask of finding the sum of odd numbers while the parent process
calculates the main task of finding the sum of even numbers.
2. Linux server configurations
The Linux server is one of the most widely used servers in the server-client model. This type of
server is easy to run and can be easily installed in existing Linux operating systems without any hassle. In
this section, few basic but essential steps of creating Linux servers will be discussed in detail. These
steps are:
1. User configuration: The changing of the root password is an important step while creating or
configuring a Linux server. The root password provides access to the system to other users. The
credentials of the user must be secure first. It is recommended to secure the system using a powerful
password using a combination of alphabets, numbers and special characters. The root password is the
access point into the system which may be used to control or develop the server.
2. Network configuration: The first step toward developing a Linux server is to make the server network
connected by assigning the server a new IP address and a hostname. The best way to do this is by
allotting a static IP address which does not change over time. This helps the user to connect to the server
using the same IP address. The next part is the setting up of the domain, hostname and DNS server.
3. Package management: The packages needed for running the specific server is an important part of
configuring a server. All the necessary packages that may be needed by the new server must be installed
before configuring the server. This is done so as to avoid any dependency issues later while server
installation and configuration.
4. Update installation and configuration: The next step after installation of all the packages is to make
sure the system on which the server is being developed is fully up to date. The newest packages can be
updated or installed via the package manager software or by enabling automatic update of the system.
This increases the security of the server as well as the system.
5. Firewalls and ip tables: This part is critical to the system and server’s security. The firewall must be
configured such that only the needed ports and addresses are allowed to connect to the server. The ip
table should also be configured and can be changed from its default state in such a way that only the
most important ports are given entry in to the server.
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Assignment 6

6. SSH: The remote access tool for Linux servers is the SSH. This method must be secured first as it is
critical to the server and has full control over it. The SSH can be used to remotely control the server and
hence must be secured first and is of top priority.
7. SELinux and further hardening: The SELinux is mainly used for making the system more secure and
the hardening the server to make it more reliable. This helps in protecting the system resources against
unauthorized access and use. This tool can also be used to harden other software or packages that are
used by the Linux server like Apache or MySQL.
2.1 UDP and TCP systems
The TCP or the transmission control protocol is used for sending packets through the internet. It
is the most common internet protocol and is used widely. The TCP acts as a messenger by sending
packets to the web server and returns the webpage to the user. The TCP is not a single way
communication protocol as an acknowledgement is also received from the server end when a packet is
delivered. TCP practically guarantees the receipt of the packets by numbering them in order. The TCP
also uses error checking protocols in order to transfer the correct packet. The UDP on the hand does not
use any error checking protocols. It works similar to the TCP but is very fast due to not having the TCP’s
continuous back and forth movement done to transfer one data packet. In UDP the packets are only
transferred to the receiver and no acknowledgment is issued. In case the recipient loses or misses some
packets in UDP transfer, there is no way to receive back those packets. UDP is only used when speed is
needed and error correction is not needed.
3. Conclusion
To conclude, the report discusses the basic concepts of server, client, processes, client/server
model, Linux server configurations, UDP and TCP. The Global ISP solution require network security
protocols like the NIST cyber security framework. This framework contains protocols that are critical to the
attacks faced by the organization Global ISP like Distributed Denial of Service attacks and huge number
of phishing attacks. The company is prone to attacks like DDoS which leads to disruption of services that
the company provides. This hampers the company’s business. The phishing attacks on the company is
another big worry for the company. These attacks lead to loss of crucial customer accounts and company
accounts and leak of critical company secrets. To prevent the DDoS attacks the company can increase
their network bandwidth in order to accommodate the attacks as well as their normal business
requirement bandwidth. To solve the phishing attacks the company faces, they can use more secure
passwords and implement more secure protocols and system safety rules for their employees.
The global ISP Company’s network security is very important and it requires the company to
protect its system and implement protocols that will be safeguard it against DDoS attacks. The DDoS
attacks target the DNS servers which are the most important part of a company who is providing online
services. The DNS server is needed in almost all its activities. The adoption of the following network
protocols can help against such attacks. Firstly, development of a denial of service response team and
plan is very important to handle when such an attack hits the company. The response plan can have
security measures that must be implemented in such situations. Secondly, securing the network
infrastructure using protocols specially developed to handle such situations can also be implemented.
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Assignment 7

This can include implementing multilevel security measures and extra bandwidth to accommodate such
attacks can be used. The phishing attacks can be prevented by implementing the following protocols.
Foremost, the most important security measure in phishing attacks is educating the employees and
teaching them security measures like proper handling of suspicious emails and downloading malicious
software. Secondly, anti-phishing browsers or security software can also be used that can automatically
detect phishing emails or websites and block them to prevent such attacks. Thirdly, another protocol is to
compulsory install and implement anti-phishing plugins, extensions or add-ons that gets integrated in the
company’s computers, mainframe and other security software and helps in automatic detection and
blocking of such malicious attacks. Such tools can detect malicious emails and files early on and prevents
access to them though blocking. To conclude, this report written here critically analyzes the network
structure of the Global ISP Company and detects its loopholes or weak areas. The report provides
solutions in the form of network protocols that can be applied to solve the problems. The report also
discusses the impact of such attacks on the Global ISP Company.
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Assignment 8

4. Bibliography
Barbanera, F. and De'Liguoro, U., Sub-behaviour relations for session-based
client/server systems. Mathematical Structures in Computer Science, 25(6), 2015
pp.1339-1381.
Binnie, Chris. Linux Server security: hack and defend. John Wiley & Sons, 2016.
Brown, R. and Anderson, M. Client-Server, Unstable Theory. Computer Science and
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Chernyi, S., The implementation of technology of multi-user client-server applications
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Christopher, G.E. and Jack, I.E.K.E., A model of local area network based application
for Inter-office communication. In Proceedings of the World Congress on Engineering
and Computer Science (Vol. 1, pp. 19-21), 2016.
Goodyear, Mark. Enterprise System Architectures: Building Client Server and Web
Based Systems. CRC press, 2017.
Götzfried, J., Müller, T., Drescher, G., Nürnberger, S. and Backes, M.,, May. Ramcrypt:
Kernel-based address space encryption for user-mode processes. In Proceedings of
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2016 (pp. 919-924). ACM.
Hosen, Md. "Isp server configuration in linux." PhD diss., Daffodil International
University, 2018.
Hossain, M., 2017. Linux system and network administration (Doctoral dissertation,
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Lubell, J. and Zimmerman, T., March. Challenges to automating security configuration
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Matotek, Dennis, James Turnbull, and Peter Lieverdink. Pro Linux System
Administration. Apress, 2017.
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Overton, W.F., Processes, relations, and relational‐developmental‐systems. Handbook
of child psychology and developmental science, 2015. pp.1-54.
Papadimitriou, S. and Moussiades, L.,. Mac OS versus FreeBSD: A comparative
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