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.
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Network
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PARTS OF A NETWORK
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Workstations
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
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.
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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.
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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.
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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.
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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.
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Routers
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PEER-TO-PEER NETWORKS
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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.
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Peer-to-Peer Network
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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.
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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.
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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.
The two software packages that allow this
type of network are called
Appleshare (for MACs)
Windows for Workgroups (for PCs)
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CLIENT SERVER NETWORKS
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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.
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Ethernet
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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.
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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.
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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.
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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.
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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.
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Token Ring
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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
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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.
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Client/Server Operating Systems
There are many different softwares out there
for this type of network. The most popular
ones are
Macintosh OSX
Microsoft Windows Server
Novell
UNIX
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Client/Server Operating Systems
Advantages
This type of network makes it easy to install new
technology and new elements.
The server can be accessed remotely, and you
can have both MACs and PCs on the network.
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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.
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NETWORK THREATS
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Hackers
A computer hacker is someone who finds
access in a computer’s security system to
break into another machine.
Hackers usually collect information on the target
computer and then try to find access into the
computer system.
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Security Threats
The most common threats are
Spam: this is unwanted commercial e-mail.
Viruses: can cause your computer to slow down
or even destroy your hard drive.
Adware/Malware: this is software that gets
installed on the computer. It can cause annoying
pop-ups or even steal information.
Information Threats: hackers steal important
information: client information, back account
numbers, etc.
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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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