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Principles of Information Technology

Networks and Hackers

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Computer System

A basic computer system is made up of two parts: hardware (physical equipment that you can touch) and software (programs installed on the computer).

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Computer Networks

Computer networks allow users to connect over distances. They allow file sharing, hardware sharing, and instant communication, making them a necessary tool for offices, schools, and homes all over the world.

A computer network consists of several components, each of which is important to making the network function correctly as a whole.


Network


Parts of a network


Workstations

These are known as desktop computers.

The computer you use at home or school would be called a workstation in a network.


Servers

Servers can look like desktop computers; however, most do not look like your “normal” computer.

Servers do not really need monitors, graphics and sound cards. What they really do need is hard drives.

In most schools, when you save your work, you are saving to a server.

By doing this, you can access your school work from any computer that is on your school network.


Modems

A modem is a device that enables computers to interpret data they receive from a network or send data in the proper form along a network.


Hubs

A hub is sort of like a car radio. Every computer that has that section of network (like a radio station) can hear everything that is being transmitted.

All the computers that are connected to that hub receive all the information that goes through it.

Usually, if you have a hub, you also have a router.


Switches

A switch is more complex than a hub and works a lot like a two-way radio. In a room full of people, only the person holding the other radio can hear what is being said.

It keeps track of which computers are where, and when something comes in, it sends it only to that specific computer, not every computer on that section of the network.

It is more secure than a hub, and faster than a hub, but not as powerful as a router.


Routers

Routers work a lot like a telephone system. Each computer is given its own unique number by the router. When information comes into the router, it is then sent along to the correct number—or in this case, computer.

There are more options built into routers than there are available to switches. A router can have the equivalent phone options of call screening and caller ID. This is beyond a switch’s capabilities.


Routers


Peer-to-Peer Networks


Peer-to-Peer Network:

This is a type of network where the computers in the network share resources among each other. Every computer on this network is equal;

all the computers run the same networking software and file systems for sharing.

Printers, scanners, and other external devices are shared by the machine they are plugged into, otherwise known as managed by.


Peer-to-Peer Network


Pros for a Peer-to-Peer Network

It is less expensive to set up a peer-to-peer network initially.

You may already own the software needed to get a peer-to-peer network set up.

This type of network does not require the installation of dedicated server hardware or expensive security software.


Cons for a Peer-to-Peer Network

If you have a peer-to-peer network, you need to be aware that shared resources, such as printers, place a special demand on the computers in the network.

Also, due to the nature of this type of network, all of the computers on the network provide access to all of the machine’s resources. The down side of this is that you can unintentionally expose private files to all the other users on the network.

There is also no data security or protection from hackers, viruses, etc.


Peer-to-Peer Operating Systems

In the peer-to-peer network operating system, each of the workstations has an operating system that tells it how to store and share resources with the others.


Client Server Networks


Ethernet Ethernet is a type of connection between

computers that forms the basis of most LANs. It also serves as one of the main methods for

connecting a computer or network to an Internet hub.

The origin of Ethernet was the idea of connecting several computers together in a network via coaxial cables.

Since that time, it has evolved into a much more sophisticated system that uses specialized Ethernet cables that connect to a central hub or router in order to network several computers together.


Ethernet


EthernetBackbone

EthernetSwitch

EthernetSwitch

EthernetHub

The Modern Ethernet Network

LAN

LAN stands for Local Area Network. A Local Area Network is a group of

computers that are linked together that share internet access, file access, applications, storage, and allow connected computers to share printers and scanners.


LAN Issues

For a LAN to work properly, a router must be installed on the primary computer that is connected to the Internet. Each computer connected to the LAN must have an Ethernet card installed.

The other issue with a LAN is that they are usually confined in a single building.


WAN

WAN stands for Wide Area Networks. A WAN is a collection of regular local

area networks that are all interconnected to form one giant network.

Oftentimes, schools and even large companies will operate a WAN on premises.


WANs Continued

Advantages Flexible access: School networks can be

created for students to access files throughout the school district.

Speed: Networks speed up the file sharing and saving process.

Disadvantages Expensive to install: WANs save money over

time, but they are expensive to set up at first. Time: WANs require maintenance of the

network, which costs both money and time. Copyright © Texas Education Agency, 2013. All rights reserved. 25

Token Rings

Token rings work by sending data from one machine to the next and so on around a ring until it ends up back where it started.

It also uses a special token passing protocol, which means that a machine can only use the network when it has control of the token.

This ensures that there are no collisions because only one machine can use the network at any given time. Copyright © Texas Education Agency, 2013. All

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Token Ring


Token Ring Issues

In order for token rings to work, all computers must check for lost or

duplicate tokens all connected computers must “vote” a

new leader to create a new token


Client/Server Operating Systems

Client/Server setup allows the network to centralize functions and applications in one or more file servers. File servers become the “heart” of this

system and provide access to files and resources, as well as providing security.

Workstations have access to the resources to files on the file servers.



There are many different software programs available for this type of network.



Advantages This type of network makes it easy to

install new technology and new elements.

The server can be accessed remotely.


Client/Sever Operating Systems

Disadvantages Client/Servers depend on their servers.

When they go down, the network will no longer work.

There is a hefty investment for a client/server network. It pays off in the long run, but it requires money to set it up.

Large networks will require dedicated staff to maintain a client/server network and to work out the “kinks” when problems arise.


Network Threats


Hackers

A computer hacker is someone who finds access into a computer’s security system to break into another machine. Hackers usually collect information on

the target computer and then try to gain access into the computer system.


Security Threats

The most common threats are Spam: Unwanted commercial e-mail. Viruses: Can cause your computer to slow

down or even destroy your hard drive. Adware/Malware: Software that gets

installed on the computer. It can cause annoying pop-ups or even steal information.

Information Threats: Hackers steal important information, such as client information, bank account numbers, credit card numbers, etc.


Hackers

Networks can take steps to protect their networks. The most common are Installing a firewall Advising caution on the net Making sure that the network is password

protected, especially if using a wireless network.

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Documents

specific computer

normal computer

school network

section of network

network function

desktop computers

school work

car radio