Network security


Network security is an intricate topic traditionally handled only by professionally trained and experienced persons. Yet, as more and more individuals become connected through computer networks, a rising number of people need to comprehend the fundamentals of security in a networked environment.

In the domain of networking, network security comprises of provisions and guidelines established by the network administrator to curb and monitor illegal or unauthorized access, misuse, alteration, or denial of the computer network and other network-based resources (Stallings 2010).

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Network security comprises of a range of computer networks, both private and public, that are employed in day-to-day tasks such as carrying out business transactions and communication among firms, public and private institutions, enterprises, and persons. Network security does just as its name goes, protects the network and manages all processes being done on the network.


The objective of the paper is to expound on network security and its importance in computer networks. Background information on computer networks will also be provided as well as risk management, network threats, firewalls, and hardware and software devices that can be used to improve the security of a computer network.

Introduction to Computer Networks

An elementary comprehension of computer networks is essential in order to understand the codes of network security. A network is any set of interconnected lines, basing this definition on the current topic, a computer network is basically a set of linked computers. Networks enable users to share resources and information, and are classified base on a variety of protocols (Network Security Threats 2011).

For instance, a classification based on the connection manner focuses on the hardware and software systems used to link the individual computer units, such as optical fiber, wireless connection, or coaxial cable communication. Networks can also be categorized on scale, this gives Local Area Network (LAN), wide area Network, virtual Private Network (VPN), among others (Stallings 2010).

Networks are made up of ‘nodes’, which are the individual computers in the network, and at least one server and/or ‘host’ computers. The nodes are linked together by communication systems, which may be private, such as that within an institution, or can be accessed by the public, such as the internet. Several private networks also use the internet.

The moment a computer network is instituted, it immediately becomes vulnerable to network security threats such as viruses and bugs that may affect the normal functioning of a computer. Besides, the personal information such as usernames, passwords, credit card numbers and other critical information may be at risk if the computer does not have adequate security measures. There are very many threats in a network, some of which are so severe and can bring down a large network consisting of thousands of computers.


In the domain of computer networks, a virus refers to a computer program that can replicate itself, similar to the biological virus. A computer virus spreads from one computer to another through an executable program that attaches itself on programs, files and folders.

It can spread through various means, for example, if one computer in a network becomes ‘infected’ with a virus, the rest of the computers in the network may become infected too if the security features are inadequate.

It can also be spread through USB devices, CD, DVD, or portable had drives. A computer virus may also spread by mailing a web address link to all addresses so that when a person clicks on the message to go the website, the virus enters this new computer.

Certain viruses are less harmful, however, some are very harmful and can infect a computer in the network through various ways (Simmonds 2004). A virus can corrupt the files or software in a computer. Others may attack the computer hardware and bring the whole computer down.

Yet, some viruses may allow a person to have partial control of a computer, this allows for unauthorized access to files and critical information stored in the computer’s hard drive. Although the Windows platform is by far the most vulnerable, other operating systems can also be attacked by viruses.

Network threats arising from viruses can be managed through various ways, however, the most common technique is to install an antivirus software. UNIX-based systems such as Mac OS and Linux are far more secure than Windows. Some anti-virus programs can scan file contents and even zipped folders while some can also scan sent and received mails, a practice known as ‘on-access scanning’ (Simmonds 2004).

Vulnerability to viruses can also be reduced by carrying out data backups regularly on storage media that are not connected to the network or computer. Security patches availed by software manufacturers can also assist in reducing attacks by viruses. Secondary storage media must be scanned before opening in the host computer.


Malware, short form of malicious software, is a program created to interrupt normal computer operations or deny a user network or computer resources, gain partial control of the computer, access files stored in the computer, gather network-based information such as passwords, and other cruel or dishonest behavior (Curtin 1997).

Malware consists of a large number of malicious programs that includes viruses, Trojans horses, worms, spyware, false adware, rootkits and other malicious programs. In 2009, malware was listed as the second most dangerous threat to computer networks. Today, millions of malware are created daily to exploit networks with weak security features.

Threats arising from malware can be removed using antivirus programs. Most antivirus have an added feature of removing various malwares from the network of individual PCs. Besides, anti-spyware software can be used to prevent spyware threats.

Denial-of-Service Attacks

A Denial-of-Service (DoS) attack is a practice aimed at making network resources unavailable to some users. This vice entails the resolute efforts of a person or group of persons to prevent an internet site or service functioning normally or bringing it down altogether. This network threat is commonly committed against websites or services hosted on high profile internet servers such as financial institutions and credit card payment services (Stallings 2010).

One mode of attack involves flooding a web server with requests in such a way that it cannot respond to legitimate communication requests, or responds in a sluggish manner that virtually renders it unusable. In general, DoS attacks are executed by either compelling the targeted systems to reset, or using up its resources so that it is unable to offer the intended services.

DoS attacks are perhaps the most malicious and hardest to prevent or manage. They are the most malicious due to the ease with which they can be launched and the difficulty of tracing their origins, and it is difficult to deny the requests of the attacker without also blocking out genuine requests for service.

DoS attacks can be prevented through various ways. The first technique is to use firewalls. Firewalls have simple instructions of blocking or allowing certain IP addresses, or ports, however, firewall are not very effective in some DoS attacks as they cannot distinguish legitimate traffic from DoS traffic. Switches and routers can also be used to prevent these attacks (Kizza 2006). Intrusion-prevention systems (IPS) have been successfully used to halt DoS attacks that have signatures attached to them.

Unauthorized Access

This is a very wide terminology as it can refer to various types of attacks, however, the objective of these attacks is to access some information that the computer or server is not supposed to reveal. Unauthorized access to a computer or server can be achieved by using viruses, malware and other malicious programs.

This form of threat can be waded off by using antivirus programs and security patches. Another strategy used by intruders to access a computer on a network is a technique known as packet sniffers. Packet sniffers can be used on a vulnerable network and they just ‘listen’ on the server for words such as password or login in the packet stream, then sends the information thereafter to the perpetrator.

This way, an intruder is able to obtain usernames, passwords, credit card information and other critical information from unsuspecting users (Bragg et al 2010). This type of threat can be prevented by using clear-text passwords, besides, data encryption can help divert such attacks.

When using a wireless network, it is advisable that one should use a long or complicated password, also, it is advisable that the strongest security supported by the wireless connection hardware should be used, such as encryption tools. Passwords can also be changed regularly.

General Methods for Preventing Network Attacks and Reducing Vulnerability on Networks

The most commonly used technique for reducing network threats is the installation of antivirus programs. These programs must be regularly updated and security patches and updates installed. Improving the security of the network infrastructure can also involve switching on features that enhance network security on switches, routers, and other hardware (Fadia 2006).

These security features ensure a secure connection, enhance perimeter security, prevents intrusion, protects identity services, and general security management. Fixing intrusion detection systems and firewalls offers protection for most areas of the network and allows for a safe connection. Working on a virtual private network (VPN) can also enhance security. VPNs provide network access control and encryption services.

Network security can also be improved by undertaking regular network security audits. A network security audit simply means that an expert comes and examines the security of the network, he also checks for loopholes that may be used attack the system and fixes them.

The audit can go beyond an inspection of the computers in the network and may comprise a site assessment of the physical security of the organization. A network security audit fixes an organization security flaws in the network and makes it difficult for perpetrators to attack the network (Network Security Threats 2011).

Since network threats come in a variety of forms and cannot be totally eliminated, it is advisable that secure updated data backups should be kept on systems that are detached from the network. None of these strategies will singly eliminate the threats arising from a network connection, but when they are used together, they can be exceedingly effectual at keeping a network safe. Besides, well –thought-out organizational policies can be effective at preventing unauthorized access to critical and parts of the network.


Bragg, R., Rhodes-Ousley, M., Strassberg, K. (2004). Network security: the complete reference. New Jersey: John Wiley & Sons, Inc.

Curtin, M. (1997). Introduction to Network Security. Available from [Accessed May 3, 2011]

Fadia, A. (2006). Network security: a hacker’s perspective. TX: Thompson Course Technology.

Kizza, J. M. (2006). Computer network security and cyber ethics. Kizza, J. M. (2006). New York: McGraw-Hill.

Network Security Threats. (2011). What Is A Network Security Audit? Available from [Accessed May 3, 2011]

Simmonds, A., Sandilands, P., van Ekert, L. (2004). An Ontology for Network Security Attacks. Lecture Notes in Computer Science, 3285: 317–323.

Stallings, W. (2010). Cryptography and network security: principles and practice. NY: Prentice Hall.

Stallings, W. (2010). Network security essentials: applications and standards. NY: Prentice Hall.


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