An Introduction to Networking

1.      Why have networks?

The reasons for networks can vary from person to person; some purposes are for communication, sharing information and resources, security, shared internet access and even convenience.

2.      What are LAN, WAN and MAN?

A LAN (Local Area Network) is geographically limited to one site or area, due to the lack of need for telecommunication. It can however have higher transfer rates in contrast to WAN (Wide Area Network) and can be cabled or wireless. A WAN (Wide Area Network) covers a broader geographical range (state-wide or country-wide) using landline data cables (e.g. ISDN, ADSL) or satellite. A MAN (Metropolitan Area Network) is limited to a small geographical area, like a city and is connected by landline data cables or fibre optic cable.

3.      Explain P2P and Client/Server networks.

P2P or Peer-to-Peer networks allow communication, the sharing of files and connection other hardware like the printer. P2P doesn’t require a server, so the costs for installation are low and simple. Also, it is used at home or in a small organization with trusted users, with all computers and users that are connected having equal rights and authority. A client/server network is a basic version of network computing, where one computer program (the ‘client’) asks another program (the ‘server’) to provide a service, providing data, delivering e-mail, sending web pages etc.

4.      What is a URL?

The term “URL” stands for “Uniform Resource Locator”, it is what helps you locate a web site address. As the name implies, it locates the resources that meet your needs.

5.      In a Client/Server network, what are the different ways to connect the computers?

Such ways are called Network Topologies, with the main topologies being bus, star, tree, ring and mesh. A bus topology is a number of computers all connected to one cable, like a backbone; if the backbone ‘breaks’ then the entire segment fails. A star topology is a number of computers that are connect to a central connection point, if one cable fails, and then only one node will fail. A tree topology is a bus and star topology joined together. A mesh topology has multiple routes connected to any other node and is nearly immune to cable failure; however, it is very expensive to set up. A ring topology is not common as a number of nodes are connected together like a ring, so a failure in any cable or device and it will bring the whole segment down.

A Trojan horse, in terms of computer software, is a program that installs malicious software while pretending to do something else. Trojan horses may seem like useful and interesting, yet harmless programs to an unsuspecting user, are however harmful when executed.

Spyware is computer software that is installed into a user’s computer that intercepts or takes partial control over the user’s interaction with the computer, without informed permission. Spyware programs can do well beyond just simple monitoring; it can also install additional software, redirecting Web browser activity and collect various pieces of personal information.

Worms are self-replicating programs that uses a network and replicates itself to attach to other computer terminals on the network. Unlike viruses, which infect or corrupt files on a targeted computer, a worm does not need to attach itself onto an existing program as it harms the network.

The term “Malware”, is a portmanteau of the words ‘malicious’ and ‘software’. It is software designed to infiltrate or damage a user’s computer without their informed consent. Malware is a word used to mean a variety of intrusive, hostile, annoying software or program code.

 What are computer hackers?

A computer hacker is a person who uses programming skills to illegally gain access to a computer network or a file.

 What do they do?

They attempt to gain access to another computer forcefully using programming skills, exploiting a loop hole in a program or network in order to access the computer without authorized access.

 What are the worst security breaches that hackers have done?

Some security breaches that can be considered as the worst would be those where large companies and organizations lose hundreds and thousands, even millions of dollars due to having their network hacked.

 Why do they do it?

Some computer hackers do it just for fun and enjoyment, while other do it for their own personal gain.

 How do they do it?

There are many ways for a hacker to break into another computer, one is where they exploit a loop hole or a weakness in security and another is where they enter the computer via a Trojan horse, where they can record most things that you do on the computer.

 What happens to them when/if they get caught?

Depending on the type of crime they have committed, many serious hackers have broken into networks that belong to big corporations, causing a lot of damage to companies, making them lose quite a bit of money in some cases. The fine for doing such, would be jail.

 How do we protect ourselves?

The most common way that hackers get into a user’s computer is by finding out their password, the best way to protect yourself from being hacked in this manner, is to never give out your password. 

 Have you ever hacked?

No, however, I would certainly like to learn how to hack, and if I do get the chance some point in my life, it would be a great skill to learn.

CIH

Estimated Damage: 20 to 80 million dollars worldwide, countless amounts of PC data destroyed CIH is recognised as one of the most dangerous and destructive viruses ever, first unleashed in Taiwan in 1998, the virus infected Windows 95, 98 and ME executable files and was able to remain within a PC’s memory where it continued to infect other executable files.  

Code Red

Estimated Damage: 2.6 billion dollars Code Red was a particularly virulent bug because it targeted computers running Microsoft Internet Information Server (IIS). Unleashed on network servers on the 13^th of July, 2001, Code Red was meant for maximum damage. Upon infection, the Web site controlled by the affected server would display the message, “HELLO! Welcome to http://www.worm.com! Hacked By Chinese!” The virus would then seek out other vulnerable servers and infect them. This would go on for about 20 days and then the virus would launch a denial of service attacks on certain IP addresses, in less than a week; this virus infected approximately 400,000 servers.  

MyDoom

Estimated Damage: At its peak, slowed global Internet performance by 10 percent and Web load times by up to 50 percent During the 26^th of January, 2004, for a period of hours, the MyDoom shockwave speeded around the world at an unprecedented rate via Internet and e-mail. It was transmitted as an attachment which appeared as an e-mail error message containing the text “Mail Transaction Failed”. When the person clicked on the attachment, the address book of the user would be infected and the worm would send itself out to the addresses found there.  

Sasser

Estimated Damage: Tens of millions of dollars Sasser began to transmit around the world on the 30^th of April, 2004, and was destructive enough to shut down satellite communication for some French news agencies. Unlike most other worms and viruses, it did not transmit itself via e-mail or through user interaction. Instead it exploited a security flaw in non-updated Windows 2000 and Windows XP systems. After successfully replicating itself, the worm would scan for any other unprotected systems and would transfer itself to them. Infected systems kept experiencing repeated crashes and instability.  

All information was obtained from the website below:  www.techweb.com