Networks and Hackers
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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 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.
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These are known as desktop computers.
The computer you use at home or school
would be called a workstation in a network.
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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.
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 What they really do need is hard drives.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Ethernet
Backbone
Ethernet
Hub
Ethernet
Switch
Ethernet
Switch
The Modern Ethernet Network
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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There are many different software programs
available for this type of network.
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Advantages
 This type of network makes it easy to install new
technology and new elements.
 The server can be accessed remotely.
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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.
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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.
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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.
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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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