The Topic Of Network Security Computer Science Essay

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Network security is the topic discussed often when a discussion arouses about the computer networks, internet, intranet, etc. Security over networks reached a most in present days and a lot much of techniques have been followed to detect and preserve networks. Here, it is about the advanced techniques in preserving the networks from computer hackers and harmful viruses. It includes all the details about hacking techniques, firewall, spyware, malware, virus, etc. It also includes the detailed account of how to prevent the computer from viruses and other treats.


Network may be defined as the interconnection between two are more computers placed inside a building or within a particular area, city, state, country or over the entire world. The connection may be made either through wires which includes LAN, WAN, etc or through wireless networks such as WIFI, GPRS, etc.

Threats due to Network:

There are various threats to computer due to the networks that is, through the internet and emails. They come under the following categories,

Viruses which affects the entire computer, is capable of formatting the hard disk drives and makes the computer completely dead.

Spyware which is commercial software that uses various methods to get installed on PC and attempt to sell things or, in some cases, scam money from the user.

Ad-ware is also a kind of spyware which always pops up an advertisement to sell its products without the knowledge or permission of user.

Also there are various techniques followed by hackers to send these malicious softwares to the computer through the networks. Those who follows these technique are called as hackers and this type of crime is called as cyber crime. It includes,



Spamming etc.


Hacking is the process which includes sending of viruses into user’s computer when they are working with the internet. Virus is nothing but a malicious code which would format any of the hard drive and that makes it not to function properly or totally damages it. Those who create and send this kind of malicious code to internet users are called hackers. They were said to be cyber crimers and they are punishable under the law. This type of cyber crime is a kind of crime under the law of government.


The act of sending an e-mail to a user falsely claiming to be an established legitimate enterprise in an attempt to scam the user into surrendering private information that will be used for identity theft. The e-mail directs the user to visit a Web site where they are asked to update personal information, such as passwords and credit card, social security, and bank account numbers, that the legitimate organization already has. The Web site, however, is bogus and set up only to steal the user’s information. The following image shows that how the process of phishing occurs in real time.

If the above link is clicked then the virus or a spyware may get into the user’s computer.


A computer virus is a computer program that can infect other computer programs by modifying them in such a way as to include a (possibly evolved) copy of it. Note that a program does not have to perform outright damage (such as deleting or corrupting files) in order to be called a "virus".

. Viruses are very dangerous; they are spreading faster than they are being stopped, and even the least harmful of viruses could be fatal. For example, a virus that stops a computer and displays a message, in the context of a hospital life-support computer, could be fatal. Even the creator of a virus cannot stop it once it is "in the wild".



. Basically, a firewall is a barrier to keep destructive forces away from your property. In fact, that's why its called a firewall. Its job is similar to a physical firewall that keeps a fire from spreading from one area to the next. As you read through this article, you will learn more about firewalls, how they work and what kinds of threats they can protect

How it Works?

A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. If an incoming packet of information is flagged by the filters, it is not allowed through.

With a firewall in place, the landscape is much different. A company will place a firewall at every connection to the Internet (for example, at every T1 line coming into the company). The firewall can implement security rules. For example, one of the security rules inside the company might be:

A company can set up rules like this for FTP servers, Web servers, Telnet servers and so on. In addition, the company can control how employees connect to Web sites, whether files are allowed to leave the company over the network and so on. A firewall gives a company tremendous control over how people use the network.

Firewalls use one or more of three methods to control traffic flowing in and out of the network:

Packet filtering - Packets (small chunks of data) are analyzed against a set of filters. Packets that make it through the filters are sent to the requesting system and all others are discarded.

Proxy service - Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.

Advancements in Using Firewall:

Firewalls are customizable. This means that you can add or remove filters based on several conditions. Some of these are:

IP addresses - Each machine on the Internet is assigned a unique address called an IP address. IP addresses are 32-bit numbers, normally expressed as four "octets" in a "dotted decimal number." A typical IP address looks like this: For example, if a certain IP address outside the company is reading too many files from a server, the firewall can block all traffic to or from that IP address.

Domain names - Because it is hard to remember the string of numbers that make up an IP address, and because IP addresses sometimes need to change, all servers on the Internet also have human-readable names, called domain names. For example, it is easier for most of us to remember than it is to remember A company might block all access to certain domain names, or allow access only to specific domain names.




There are many creative ways that unscrupulous people use to access or abuse unprotected computers:

Remote login - When someone is able to connect to your computer and control it in some form. This can range from being able to view or access your files to actually running programs on your computer.

Operating system bugs - Like applications, some operating systems have backdoors. Others provide remote access with insufficient security controls or have bugs that an experienced hacker can take advantage of..

Denial of service - You have probably heard this phrase used in news reports on the attacks on major Web sites. This type of attack is nearly impossible to counter. What happens is that the hacker sends a request to the server to connect to it. When the server responds with an acknowledgement and tries to establish a session, it cannot find the system that made the request. By inundating a server with these unanswerable session requests, a hacker causes the server to slow to a crawl or eventually crash.

E-mail bombs - An e-mail bomb is usually a personal attack. Someone sends you the same e-mail hundreds or thousands of times until your e-mail system cannot accept any more message


Be careful about using MS Outlook. Outlook is more susceptible to worms than other e-mail programs, unless you have efficient Anti-Virus programs running. Use Pegasus or Thunderbird (by Mozilla), or a web-based program such as Hotmail or Yahoo.

Install an Anti-Virus program(ex. Norton, F-Secure, Sophos or McAfee.) Also available is the free AntiVir virus scanner. Make sure you keep your virus definitions updated and run a full system scan weekly.

to a safer, more secure browser such as Firefox or Opera.


Networks can be prevented in the above explained ways either by protection or by prevention. It is to be noted that any

antivirus software or likemost are used by you, the updated version must be used because day by day new and lot more viruses gets developed by the user and sent to the users. There are more facts to be discussed on this fact which are beyond the scope of the paper.As a computer science student we should comeout with innovative solutions to tackle this great security problem.