Unit 2 Networks Security

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THE BRITISH SCHOOL of ARAGON

4 ESO

UNIT TWO

NETWORKS
SECURITY
Produced by Edgar Mahtani

&

ICT

CONTENTS
1. Networks: Definitions and Types......................................................3

1.1 Types of Networks ............................................................................3
2. Network Connection: Devices and Set-Up......................................7

2.1
2.2
2.3
2.4

Physical Devices...............................................................................7
Wireless Networks ...........................................................................9
Basic Network Configuration in Windows ........................................10
Basic Wireless Network Configuration in Windows...........................14

3. Sharing Network Resources .............................................................15

3.1
3.2
3.3
3.4
3.5

Share folders and files in Windows XP..............................................15
Share folders and files in Windows 7 ...............................................16
Multimedia home network................................................................17
Share a printer .................................................................................17
Install a shared printer ....................................................................17

4. Computer Security..............................................................................18

4.1 Against what must we protect ourselves?........................................18
4.2 Active & Passive security .................................................................19
4.3Silent threat ......................................................................................19
4.4 Viruses in new devices ....................................................................21
4.5 The Antivirus ....................................................................................21
4.6 Firewall ............................................................................................23
4.7 Anti-Spam software .........................................................................24
4.8 Anti-Spy software .............................................................................24
5. Interconnection between Mobile Devices ......................................26

5.1 Transmitting via Bluetooth ...............................................................26
5.2 Transmitting via Infrared ..................................................................26
 Things to remember!!.....................................................................27
 How to make a Network Cable .....................................................27
 Set Up a wifi router.........................................................................29

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 On-line antivirus..............................................................................31

1. NETWORKS: DEFINITIONS AND TYPES
When we work with a computer we usually do it in an individual way and with the
necessary programs already installed in it. However, the need to share information with
other computers which are within a short or long range has made it necessary for the
computers to be inter-connected. Today, not only can we connect our personal computers,
but we can also connect other devices such as printers, mobile/cellular phones, TV
cameras, PDA’s, multimedia devices, etc., thanks to the latest wireless interconnection
technology of Wifi or Bluetooth.
 Wi-Fi (short for "wireless fidelity") is a term for certain
types of wireless local area network (WLAN) that use
specifications in the 802.11 family (an evolving family of
specifications for wireless local area networks
(WLAN’s) developed by a working group of the Institute
of Electrical and Electronics Engineers (IEEE)). The
term Wi-Fi was created by an organization called the
Wi-Fi Alliance, which oversees tests that certify product
interoperability. A product that passes the alliance tests
is given the label "Wi-Fi certified" (a registered
trademark).
 Bluetooth is an open wireless technology standard for
exchanging data over short distances (10m) and using
short length radio waves (2,4 GHz) from fixed and mobile
devices, creating personal area networks (PANs) with
high levels of security. Created by telecoms vendor
Ericsson in 1994.
We refer to a computer network as group of computers and electronic devices which are
interconnected with each other in order to share resources, information and other services.
The elements that form a computer network are the computer equipment, the means
of interconnection and the programs or protocols which allow the information to be
accessed by all the computers within the network.

1.1

TYPES OF NETWORKS

 NETWORKS ACCORDING TO THEIR SIZE / SIGNAL RANGE
 A personal area network (PAN) is the interconnection of information technology
devices within the range of an individual person, typically within a range of
10m. For example, a person travelling with a laptop, a personal digital assistant
(PDA), and a portable printer could interconnect them without having to plug
anything in, using some form of wireless technology. Typically, this kind of personal
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area network could also be interconnected without wires to the Internet or other
networks.

 A local area network (LAN) is a network that interconnects computers within a
building, with a limited range because of the maximum range of the cables
(90m) or the ranges of wireless aerials (150m). For example, the network in your
school connects computers, printers and other devices in the area of a building with
several floors.
 A metropolitan area network (MAN) is a network that interconnects users with
computer resources in a geographic area or region larger than that covered
by even a large local area network (LAN) but smaller than the area covered by
a wide area network (WAN). The new municipal networks that use long range
wireless connection with aerial dishes or via new protocols such as Wimax (A
wireless 802.16 communication protocol that uses frequencies between 2,5 GHz &
11GHz. It needs special aerials and its estimated range is close to 50 km) and that
have a range from 5 to 50 km are an example of this type of network.
 A wide area network (WAN) is a network that interconnects computers within an
extensively wide geographical area, such as a country or a continent (. It
usually helps itself with infrastructures that already exist, such as the telephone
network or the fibre optic cable.
 NETWORKS ACCORDING TO THE PHYSICAL MEANS USED
 Wired networks: uses cables to transmit data.
 Wireless networks: the interconnection of
information technology devices within the range
of an individual person, typically within a range
of 10 meters.. Sometimes it’s also referred to as
Wi-Fi network or WLAN. This network is
getting popular nowadays due to easy to setup
feature and no cabling involved. You can
connect computers anywhere in your home
without the need for wires. To avoid any other
computer connecting to a wireless network you
can set it up with an encrypted access code (a
network key). This will protect your network.
 Mixed networks: some areas are connected via cables and others are wireless.
Exercises:
1. Explain the difference of the range area of the different types of networks.
2. What is a computer network and which elements form it?
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 NETWORKS ACCORDING TO THEIR TOPOLOGY
In computer networking, topology refers to the layout of connected devices. Topology
can be considered as a virtual shape or structure of a network.


A bus network is an arrangement in a local
area network (LAN) in which each node (a
workstation or other device) is connected to a
main cable or link called the bus. The
illustration shows a bus network with five
nodes. Each node is shown as a sphere, the
bus appears as a heavy horizontal line, and
connections to the bus appear as vertical lines
(also known as a lineal connection). The main
disadvantage. any problem in the main cable will stop the network working and the
accumulation of data traffic in the structure can slow down the communication in the
network.



A star network is a local area network (LAN) in which all
nodes (workstations or other devices) are directly
connected to a common central computer via a *hub. Its
advantage is that every node works independently;
however, the information from one terminal can be sent to
all the others, allowing the communication between all the
nodes to be quicker when working simultaneously. To
avoid all workstations receiving the same information a *switch can be used as the
main unit; this will allow you to send the information to a specific node.
*Hub: a device that allows the connection of several computers using a cable
network. The data received is sent to all the computers connected to it.
*Switch: a device used in cable networks which selects the node which has priority
to receive the information at any particular time. As such, it only sends the data
packet to its specific destination.



A ring network is a local area network (LAN) in which the
nodes (workstations or other devices) are connected in a
closed loop configuration. Adjacent pairs of nodes are directly
connected. Other pairs of nodes are indirectly connected, the
data passing through one or more intermediate nodes.



A tree network is a combination of two or more star networks
connected together. Each star network is a local area network
(LAN) in which there is a central computer or server to which
all the workstation nodes are directly linked. The central

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computers of the star networks are connected to a main cable called the bus. Thus,
a tree network is a bus network of star networks.



A mesh network is a local area network (LAN) that employs one
of two connection arrangements, full mesh topology or partial
mesh topology. In the full mesh topology, each node
(workstation or other device) is connected directly to each of the
others. In the partial mesh topology, some nodes are connected
to all the others, but some of the nodes are connected only to
those other nodes with which they exchange the most data.

 NETWORKS ACCORDING TO THE TRANSMISSION OF DATA


Simplex: The communication occurs in one direction only. Only present in some
PAN devices (Bluetooth headphones)



Half Duplex: Provides communication in both directions but not simultaneously
(only one way at a time). In a LAN, one workstation can send data on the line and
then immediately receive data on the line from the same direction in which data was
just transmitted.



Full (Double) Duplex: Provides communication in both directions and
simultaneously in the same line. At present all computer networks use protocols that
allow simultaneous and two way communication.
Exercises:
3. What differences can you see between a star and a tree network? Which of
these two will use a large number of switches ?
4. Create a table to show the different types of networks according to the
transmission of data. Explain their differences.

2. NETWORK CONNECTION: DEVICES & SET UP
2.1

PHYSICAL DEVICES

 NETWORK INTERFACE CARD
A network interface card (NIC) is a hardware device that sends
and receives information to and from all other computers. It is
connected to the motherboard via a bus PCI (it connects peripheral
devices such as sound and network cards, modem cards, TV
receivers, etc.) At present the local area networks are Ethernet types
because they use the IEEE 802.3 protocol. The connection speed is usually 10/100 Mbps.
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The most modern ones have 1000 Mbps technology, although the speed will also depend
on the different types of connectors (RJ45 or BCN) and connection cables (coaxial,
twisted pairs or fibre optic). Each card has a specific code so that it can be identified in the
network. This code is known as the MAC address (command interpreter: CMD +
ipconfig/all) of the system, also known as the physical address: it is a hexadecimal
number made of six pairs of digits (e.g. 00:5C:5D:11:08:F3).

 NETWORK CABLES
In order to carry out a wired connection, network connection cables are required.
There are three types of connection cables.


Unshielded Twisted Pair (UTP) Ethernet Cable

Twisted pair cabling comes in two varieties: shielded and
unshielded. Unshielded twisted pair (UTP) is the most popular
and is generally the best option for school networks. The quality
of UTP may vary from telephone-grade wire to extremely highspeed cable. The cable has four pairs of wires inside the jacket. Each pair is twisted
with a different number of twists per inch to help eliminate interference from adjacent
pairs and other electrical devices.


Unshielded Twisted Pair Connector

The standard connector for unshielded twisted pair cabling is an
RJ-45 connector. This is a plastic connector that looks like a large
telephone-style connector. A slot allows the RJ-45 to be inserted only
one way. RJ stands for Registered Jack, implying that the connector
follows a standard borrowed from the telephone industry. This
standard designates which wire goes with each pin inside the
connector.


Coaxial Cable

Coaxial cabling has a single copper conductor at its centre. A plastic layer provides
insulation between the centre conductor and a braided metal shield. The metal shield
helps to block any outside interference from fluorescent lights,
motors, and other computers. Although coaxial cabling is difficult to
install, it is highly resistant to signal interference. In addition, it can
support greater cable lengths between network devices than
twisted pair cable.


Fibre Optic Cable

Fibre optic cabling consists of a centre glass core surrounded by
several layers of protective materials. It transmits light rather than
electronic signals eliminating the problem of electrical interference. This
makes it ideal for certain environments that contain a large amount of
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electrical interference. It has also made it the standard for connecting networks
between buildings, due to its immunity to the effects of moisture and lighting.
Fibre optic cable has the ability to transmit signals over much longer distances than
coaxial and twisted pair. It also has the capability to carry information at vastly greater
speeds. This capacity broadens communication possibilities to include services such
as video conferencing and interactive services. The cost of fibre optic cabling is
comparable to copper cabling; however, it is more difficult to install and modify.
10BaseF refers to the specifications for fibre optic cable carrying Ethernet signals.
THE SWITCH
A switch (sends data to PC’s of
choice) is used to connect multiple
computer
equipment
in
an
Ethernet network with a star
topology. Since it is an external
device it becomes part of the
hardware peripherals used in the
operation of a computer system. It is
usual that one of the switch ports is
connected to a router to have access
to Internet. Although hubs and
switches both glue the PCs in a
network together, a switch is cheaper
than before and a network built with
switches is generally considered
faster than one built with hubs. These
switches not only receive data
packets, but also have the ability to inspect them before passing them on to the next
computer. In other words, they can figure out the source, the contents of the data, and
identify the destination as well. Because of this uniqueness; it sends the data to the
relevant connected system only, thereby using less bandwidth at high performance
rates.
Ethernet Gigabit networks
Until a few years ago, networks were made up of
network cards and 10/100 type switch that could
transmit up to 100 Mb per second within the local
network. At present there are network cards and
10/100/1000 type switch that can transmit up to 1 Gb
per second within the local network. Although more
expensive equipment, they are an enormous help for
the traffic of data in a LAN network.
 ROUTER

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A router is a device that interconnects two or more computer networks, and
selectively interchanges packets of data between them. Each data packet contains
address information that a router can use to determine if the source and destination are
on the same network, or if the data packet must be transferred from one network to
another. Where multiple routers are used in a large collection of interconnected
networks, the routers exchange information about target system addresses, so that
each router can build up a table showing the preferred paths between any two systems
on the interconnected networks. The router is connected to at least two networks and
decides which way to send each information packet based on its current understanding
of the state of the networks it is connected to. A router is located at any gateway (where
one network meets another), including each point-of-presence on the Internet. A router
is often included as part of a network switch.
Exercises:
5. How can you find out the MAC address of your network card? Which
command interpreter do you use?
6. Use Internet to find out the colours used by unshielded twisted pair cables.
7. If you had to choose a device to connect the network equipment of a local
network, which order of preference would you choose from these?
Switch 10/100 – Hub – Switch 10/100/1000

2.2

WIRELESS NETWORKS

The connection of wireless devices is carried out by electromagnetic waves which
spread out through space between an aerial that sends and another that receives. At
present the protocol connections are IEEE 802.11b, IEEE 802.11g and the new protocol
802.11n, capable of reaching maximum speeds of 300 Mbps.
In order to interconnect a wireless access point with a computer, this last one must
have a wifi reception aerial and the software that manages it. The electromagnetic waves
sent may be captured by any wifi reception aerial which is in a range less than 50 or 100 m
(depending on the obstacles in between).
Hybrid networks are those LAN networks that are connected by cables but which
some of its nodes is a wireless access point that allows the wireless connection of other
wifi devices. The routers that have wifi service only need access points to Internet if they
want to increase the range.
 Types of wifi peripherals


A wireless router is a device that performs the functions of
a router but also includes the functions of a wireless access
point. It is commonly used to allow access to the Internet or
a computer network without the need for a cabled

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connection. It can function in a wired LAN (local area network), a wireless only LAN,
or a mixed wired/wireless network.


A PCI wireless adapter card connects to a desktop computer's PCI
bus. Because the PCI bus is contained inside the computer, the unit
must be opened and the wireless network adapter installed inside.



A Wireless miniPCI are integrated into the motherboards of notebooks,
consoles, tablets and mobile phones.



A Wireless USB is connected to a usb port, and is similar to a pen
drive.



A Wireless PCMCIA is connected via the expansion slot of
laptops.

 Types of wifi aerials
Many of the previous devices have a SMA connector as a wireless aerial. These
aerials can be changed depending on the range that you need or even use extension
leads to separate them from computer equipment. There are three types of aerials:





Omnidirectional: they cover an arc of 360° but with a short range.
Directional: they cover an arc from 4 to 40° with a greater range.
Sector: they cover an arc from 90 to 180° with a range that lies between the
two above.

Types of wi-fi passwords

In order to avoid any equipment connecting to a wireless network without permission of
the administrator an encrypted key is introduced:
WEB: This involves the simplest type and can have 64, 128 or 256 bits. These type of
keys are easily hacked because they continuously send the key in air when there is a
transmission of data between connected devices.
WPA & WPA2: These types of encryption can also be made complicated with protocols
that have a greater number of bits. Its security lies in that it only uses the key to connect a
new device and not when you send or receive packets of information. To avoid any risk of
intrusion you can use system filters together with the wifi password.
MAC filter: when activated this system will not allow any wireless device to connect to
our network and only those computers whose MAC address we have previously
authorised can connect.
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2.3

BASIC NETWORK CONFIGURATION IN WINDOWS

In order for a network to work properly you need to have the computer systems
properly connected and set up the devices with a series of parameters so that these can
share information. In Windows the first thing to take into account is the name of the system
and the workgroup in which we want our computer to belong:


Windows XP

Start Menu -> Control Panel -> System Properties. In the Computer Name tab we
can see the complete name of the computer system and the workgroup.


Windows 7

Start Menu -> Control Panel -> System and Security -> System -> Advanced
system settings. In the Computer Name tab we can see the complete name of the
computer system and the workgroup. If you want change this information, click on the
Change button and carry out the changes on the window that appears.

The communication protocol used by computers in the networks is an IP (Internet
Protocol) type. This means that each computer has a unique code so that it can be
identified in the network. This code is known as an IP address. The IP address is made
up of four numbers of up to three digits each one, separated by dots. Each number of the
IP can’t be higher than 255. For example, a valid IP address can be 168.168.0.5. This IP
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address has a hierarchical value; in other words, the first three numbers indicate the range
of the network and the last one the individual device.
 Automatic network connection set up
For the automatic set up you must have an option in the router settings called DHCP
automatic server activated.


Step 1
o Windows XP

Start Menu -> Control Panel -> Network and Internet connections -> Network
connections. A window will open showing the network connections that your computer
has activated.
o Windows 7
Start Menu -> Control Panel -> Network and Internet -> View network status and
tasks.



Step 2
o Windows XP

Double click on Local area network and select the Properties button which appears in
the dialogue box. Then double click on TCP/IP Protocol. As the router is set up with the
DHCP server activated you don’t have to enter any information, you only need to leave the
Obtain an IP address automatically and Obtain DNS server address automatically
selected.
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o Windows 7
Change adapter settings -> right hand click on the Local Area Network and select
the Properties option. In This connection uses the following items: double click on
Internet Protocol Version 4 (TCP/IPv4). As the router is set up with the DHCP server
activated you don’t have to enter any information, you only need to leave the Obtain an IP
address automatically and Obtain DNS server address automatically selected.

Manual network
connection set up


The
other
option
is
assigning the
IP
address,
the
subnet
mask and the
Default
Gateway (the router’s IP address) manually.


Step 1: Assign the IP address

You must know the IP address of the router so that we can assign an IP address which
is in our same range (i.e. with the same first three digits and whose last digit is different to
the router’s IP. If we have the default gateway 192.168.0.1, our computer must have an IP
address 192.168.0.X (where X must be between 2 and 255 and mustn’t be repeated in any
other computer of the local network.


Step 2: Assign the subnet mask

The subnet mask is the accepted range of IP addresses that
work in the same network which at the same time forms part of a
local network. It lets you set up small networks within a local
network. Other subnet masks could be 255.255.0.0 or 255.0.0.0.



Step 3: Assign the DNS server

The DNS server is the address of the computer server of our Internet Service Provider
(ISP), and the primary address as well as the alternative address must be provided by the
ISP (Movistar, Jazztel, etc.) Our ISP will give us two addresses to avoid any loss in the
service in case one is lost or because of service saturation. A DNS server has a data base
which relates the domain address (e.g. www.britanicoaragon.com) with the IP address of
the computer that has the information of the Internet page of that domain.
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2.4 BASIC WIRELESS NETWORK CONFIGURATION IN WINDOWS
Follow the steps from the previous section to set up the wireless network (fixed or
automatic (DHCP) IP addresses). The difference between a cable and a wireless network
is that the last one has to be within the area of a network in range and
write the network password. You have to access the specific program to
manage wireless networks of your wireless wifi or Windows own:


Step 1

Start Menu -> Control Panel -> Network and
connections -> Network Connections


Internet

Step 2

Choose the wireless connection and click on the View wireless networks button, and
a list of the networks detected by your aerial will appear. The signals with a padlock
indicate those that have their security activated.


Step 3

Double click the network you want to connect to and you will
be asked for a security key or password. Write the key and
connect. After a few seconds the DHCP server will assign you an
IP address, you will be able to surf the Internet and have access to the resources of your
local network.
In this configuration we can have access to various wireless networks and arrange your
favourite ones. This arrangement can be changed by clicking on the task Change the
order of the preferred networks which appears in the window of the available wireless
devices.
IMPORTANT: whenever you wish to connect to an open wifi
network they should be known to you or of known public organisations
(Town Hall, Civil Center, etc.), otherwise behind an unprotected
network their maybe a computer pirate that offers this as a ‘bait’ to
obtain information from the computers that connect to that network. It
is advisable not to surf with private information (social networks,
banks, e-mails…) when you are connected to an open wireless
network because you run the risk of your passwords been discovered or stolen.

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3. SHARING NETWORK RESOURCES
3.1 Share folders and files in Windows XP
First of all, it is convenient to say that it is only convenient to share those resources that
you really wish other users to have access to.


Step 1

To share a folder from your hard disk, right-hand click on the folder. A contextual menu
of the tasks that you can carry out will appear. Select the Share and security option.


Step 2

A dialogue box to share resources will appear. In this window Set up the name of the
folder that you want to share and which will be known as for the other users of the
network. Remember that the name must have more than eight characters or special
symbols like dashes, accents, slash, etc. By marking the check box Share this folder in
the network you can also add other options like Allow other network users change my
files. We choose this option when you don’t mind other computers in the network
changing or creating new folders in the shared folder.


Step 3

Apply and accept the changes: the icon of the folder will change and a hand which
indicates that the folder is shared will appear below it. Special permissions of users in the
folder are assigned from the Share and security menu that we have seen, but in the
advanced option. In this window a special permission button will appear where you add
new users and permit or deny the control of the contents of that folder.
Specify permissions to specific users in Windows XP
network:
To specify permissions with respect to the users you must
view the Share and security tool in its advanced format.
Start menu -> Control Panel and then in the above menu
click on Tools -> Folder options. In the tab View there is an
advanced set up area where you must unmark the check box
that reads: Use simple file sharing (recommended). Accept.

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3.2 Share folders and files in Windows 7
Windows 7 offers a home network environment called Homegroup which allows the
computers connected to the same LAN to share files, devices, printers, libraries, play
multimedia files, etc. In order to belong to the Homegroup a password assigned to you by
the network administrator must be introduced.
Start Menu -> Control Panel -> Networks and Security -> Network and Sharing
Center
From this screen you can set up all the
aspects of Windows related to networks and
Internet access. Change the set up by clicking
in the Homegroup and sharing options. In
this screen you are informed of the existence
of a homegroup and allows you the possibility
to join the group by clicking on the Join now
button, and follow the steps until you finish by
typing a password that the network
administrator will give you. Right hand click
on any folder to select Share with to share
files, printers, etc.

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3.3 Multimedia home network
In the last years there has been a growth in electronic equipment with local network
connections (both Ethernet and Wireless) which allows you to set up a home network
with the computers, televisions, console games, mobile phones, etc. By having all the
equipment connected to each other you can share files or, even better, play multimedia
files stored in other network equipment. Thanks to the certified DLNA connection of
equipment, today it is possible to watch on TV a video from the computer or see a photo
stored in a mobile in a console game.
The Digital Living Network Alliance
(DLNA) created by 250 producers of home
electronic devices which allows the devices
of the same network to connect amongst
each other to share multimedia contents.

3.4 Share a printer
There are two ways of sharing a printer in a network:
With its own IP address: via a printer with network technology that has a network card
and via the menus set up the IP data, default gateway and subnet mask. The advantage
lies in that it doesn’t depend on any other network device to work.

3.5 Install a shared printer
Start Menu -> Devices and Printers -> Add a printer

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4. COMPUTER SECURITY
Computer security is the process of preventing and detecting unauthorized use of your
computer. Prevention measures help you to stop unauthorized users (also known as
"intruders") from accessing any part of your computer system. Detection helps you to
determine whether or not someone attempted to break into your system, if they were
successful, and what they may have done.
An integrated system: does not allow any unauthorized user to modify any information
on the computer.
A confidential system: does not allow any user without authorisation in the system to
view data.
These characteristics that limit the use of information must go together with the
availability concept because the systems must be available so that authorised users can
use them adequately. Do you think your computer system at home or school is safe? Can
any other user view your files when they use your computer? Do you protect your identity
by using passwords and security keys?

4.1 Against what must we protect ourselves?


Against ourselves: sometimes we delete files without realising it, we delete
programs which are necessary for the security of the computer or we accept e-mails
which are dangerous for our computer system.



Against accidents and breakdown: it can damage our computer system and
cause loss of data.



Against intruders: from the same computer or from another computer in the
network that can get access to data in our computer.



Against malicious software or malware: programs that take advantage of our
computer to install itself and access information, damage our system or even make
the computer system useless (unusable).
Activity:
Visit the National Institute of Communication Technologies (INTECO) www.
Inteco.es -> Security -> INTECO-CERT -> Statistics. Which viruses have had the
most impact on Spanish systems in the last twenty-four hours? What is the function
of this Institute? Download free software, protection, online courses, statistics,
response & support, protecting the underage, etc.
http://www.safeandsecureig.org/

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4.2 Active & passive security
There are two types of tools or recommended practices related to security:


Active security techniques (to avoid damaging computer systems)
1. The use of appropriate passwords.
2. Data encryptions.
3. The use of computer security software.



Passive security techniques (to minimise the effects or disasters caused by an
accident, a user or malware)
1. The use of adequate hardware against accidents or breakdowns (inadequate
electrical connections, use of SAI devices, etc.).
2. Carry out data security copies and backups of the operating system in more
than one device and in different locations.

A very good practice to remember, as explained before, is the creation of logical
partitions in the hard disk so that you can store files and carry out backups in a different
unit to the operating system.

4.3 Silent threats
Computers are exposed to a series of small programs or malware which can enter our
computer via e-mails, surfing through false or infected webpages, transmitting affected
files from other devices such as magnetic disks, memory devices, CD, DVD, etc. We can
find the following types of malware software:
 Computer virus
A program which installs in the computer without the knowledge of
the user with the objective of spreading to other computers and carry
out actions for which they were programmed for. For example, from
minor jokes which do not imply the destruction of files, or slowing
down or shutting down the computer system, to the complete
destruction of hard disks.
 Computer worm
A type of virus that multiplies and infects all the nodes of a computer network. Although
they may not delete files they will slow down infected computers and its
entire network. They are usually included in malicious e-mails and many
are able to be sent automatically to all the contacts of the e-mail
program. Apart from the protection system you may use with your
computer, it is always advisable to be careful when you open e-mails,

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especially if you don’t know who they are from. Whenever in doubt, even with ones that
you may recognise the sender, don’t open them!!

 Troyan
A small application that hides in other utility programs, desktop
backgrounds, images, etc., that doesn’t want to delete information,
but wants to create an entrance into our computers so that another
user or application may gather information from our computer or
even to take complete control of the computer system from a remote
site. It uses other applications to get into the computer system and
these may come from the web, e-mails, chats or ftp servers.
 Spy
This is a program that installs itself into a computer without the user
knowing it so that it can gather information to send it to other Internet
servers which are managed by publicity companies. The information
that a spy gathers is usually used to send us spam or unwanted (trash)
e-mails. Computers affected by spyware usually find their connection to
Internet is slowed down.
 Dialer
These are programs installed into the computer which use the users
Internet modem telephone connection to make high cost phone calls
which generates expensive phone bills for the user and financial
benefits for the creator of the dialer. If the connection to the Internet is
via an ADSL router this problem can be avoided. It is advisable to
inform your Internet Service Provider to block all calls to telephone
services that charge you (803, 806, 807, etc.).
 Spam
Also known as trash mail, it sends mass publicity e-mails to the address of any existing
e-mail. Its objective is to sell its products. The main effects on your computer are that it
saturates your e-mail server and hides other malicious e-mails. All e-mail programs to day
include a black list of contacts to block their e-mails and they store suspicious e-mails in a
folder called spam or trash e-mail.
 Pharming
This consists of replacing webpages by a local server installed in
your computer without the user knowing it. This replacement is used to
obtain bank data from the users and then carry out illegal financial
crimes.
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 Phishing
An illegal practice which consists of obtaining confidential information from users with
electronic banking via e-mails that request such information. This fraud is camouflaged by
giving the e-mail the official appearance of our bank and uses the same corporative
(company) logo.
 Keylogger (key register)
By using malware or even hardware devices, its aim is to register
all the keys that a user keys in the keyboard to store them in a file
and send them to Internet to the creator of the keylogger. In this
way, private information such as passwords, banking data, private
conversations, etc. can be obtained. Keyloggers may also come in
hardware devices which are connected to the keyboard or CPU. With
a simple visual testing you can discover the spying device.
 Rogue software
Also known as a false security program, these are false antivirus or anti-spy
programs which makes the user believe that their computer system is infected by a virus
or spy programs so that they buy a program the eliminates this false infection. If you have
any doubts about a particular security program you can consult a numbers of lists that
exist to inform users.


http://www.infospyware.com/rogue-software/

 http://www.spywarewarrior.com/

4.4 Viruses in new devices
The appearance of new electronic devices such as tablets, smartphones, console
games, etc. has led to an increase of malware programs that attack these new apparatus.
The most common means of spreading computer viruses in these electronic devices are
surfing infected webpages, files transmitted via Bluetooth or portable memory devices,
downloading free applications, installing demo games, etc.

4.5 The Antivirus
The purpose of any antivirus program is to detect, stop from running and delete any
malware. It compares analysed files from the computer with its own data base of malicious
files, also known as signatures. So that the antivirus programs functions properly its data
based must be kept updated because new viruses appear constantly. Nowadays, most
antivirus programs include an automatic update service through Internet.
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Many antivirus programs also use heuristic analysis to identify new malware or variants
of known malware (they speed up the process of finding a satisfactory solution). The
heuristic technique of an antivirus consists of analysing the internal code of the file to
determine if it is a virus, even if it isn’t included in the data base of malware programs. This
is an important way of detecting new viruses which still have not been included in the data
bases. Antivirus programs have different levels of protection:
 Memory resident level: this consists in continuously running and analysing
programs which are executed in the computer, incoming and outgoing e-mails,
webpages, etc. The resident antivirus uses computer resources and may slow it
down.
 Complete analysis level: this consists in analysing all the files from the hard disk,
the boot, RAM memory, etc. of the computer. These analysis are done much faster
the more you repeat the procedure because the good files are marked off to avoid
analysing them again in further analysis.
 Free antivirus
Many tools are appearing lately which allow you to analyse the computer in a remote
way from Internet; known as online antiviruses. These are some examples of the free
antiviruses for different operating systems and analysis through Internet:
FOR WINDOWS: Panda Cloud Free edition: http://www.cloudantivirus.com

AVG Free Anti-virus: http://free.avg.com

Avira antivir personal: http://www.avira.com

Comodo

Antivirus: http://www.comodo.com

FOR MAC OS X:

ClamXAV, Sophos & Antivirus.

FOR ANDROID:

AVG Mobilation, NetQin & Norton Mobile Secure.

FOR LINUX:

LINUXAVG Free anti-virus, AVAST Linux free & ClamTK.

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ON-LINE:

PANDA Active scan 2.0: http://www.pandasecurity.com
ESET On-line Scanner: http://eos.eset.es
Bitdefender QuickScan: http://www.bitdefender.es

4.6 Firewall
The purpose of a firewall program is to allow or not communication between the
applications in our computer system and the network, and also avoid intrusion from other
systems to ours via the TCP/IP protocol. It will control the traffic between the computer and
the local network and Internet. In order for the firewall to function properly it must have a
series of conditions set up for the applications that have permission to communicate with
the network (Internet Explorer, e-mail clients, antivirus updating applications, etc.) and to
stop the communication of applications which you don’t wish to interact with Internet.
When the firewall detects an application that wants to communicate with Internet and
doesn’t have the required set up conditions, a window will appear which asks you what to
do with the respective communication. Windows XP and Windows 7 have their own
firewall which is simple to set up:
o

Windows XP
 Step 1
Start Menu -> Control Panel -> Security Center -> Windows Firewall.
 Step 2
Activate the firewall. Open the Exceptions tab and add the programs you wish to
allow access.

o

Windows 7
 Step 1
Start Menu -> Control Panel -> System and Security -> Windows Firewall.
 Step 2
With the Allow a program through Windows firewall option you can add
exceptions to the firewall.
 Step 3
In the Advanced settings option in Windows Firewall you can give entry or exit
permissions to each program.

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Routers that have access to Internet have their own firewall. To set them up you have
to enter the routers set up configuration using the IP of the default gateway of your
network in the browser.

 Free firewalls
These are some free versions of firewalls you can also use:


ZoneAlarm: http://www.zonealarm.com



Comodo Firewall: http://personalfirewall.comod.com



Ashampoo Firewall: http://www.ashampoo.com/en/eur



Agnitum Outpost free: http://free.agnitum.com

4.7 Anti-Spam software
Anti-spam programs are based on filters which are capable of detecting trash mail from
the client (your computer) as well as from the server (your e-mail provider). Spam or trash
mail is sent in a massive and indiscriminate way by publicity companies. The fight against
spam mail is complicated if normal e-mails are to be respected at the same time.
These filters analyse the e-mails before the client downloads them. The means of
detection is based on a list or data bases of spam mails, on the analysis of the veracity of
the sender, etc. At present, most antivirus include in their security distributions an antispam filter.
There are two types of e-mails: POP3 which is used by Microsoft Outlook, Mozilla
Thunderbird or Linux Ubuntu Evolution to download e-mails from the server; and the
webmail e-mail which is viewed via webpages such as Hotmail, Gmail, Mixmail or Yahoo.
In both cases spam e-mail filters must exist in the server which may be completed with
programs installed in our computers.

4.8 Anti-Spy software
Spy programs are installed in our computers camouflaged (hidden) in free inoffensive
utilities that we download from Internet. Spyware collect information about our surfing
habits, programs installed, etc. and very often they can kidnap our homepage from the
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browser and send us to a blank page, of publicity, using a means known as hijacking
(when a homepage is changed without permission of the user).
The purpose of these anti spy programs is similar to the antivirus because it compares
the files of our computer with the data base of spy files. This is the reason why this
software is also very important to have installed in our computers.

 Free anti-spyware
Window 7 includes its own anti-spy program called Windows Defender. Linux doesn’t
have anti-spy programs incorporated because it has a low number of attacks, but there are
complements for the browser to close webpages with spyware. These are some:


Ad-Aware: http://www.lavasoft.com



Spybot Search & Destroy: http://www.safer-networking.org



Malwarebytes Anti-Malware: http://www.malwarebytes.org



IObit Malware Fighter Free: http://www.iobit.com/malware-fighter.html

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5. INTERCONNECTION BETWEEN MOBILE
DEVICES
Although most devices can be connected with special connecting cables or USB types,
there are two wireless technologies in the market which stand out when it comes to
connecting devices such as mobile phones, hand free kits, netbooks, hand-held computers
and tablets: they are Bluetooth and IrDA (infrared).
 Pairing Bluetooth devices
A permanent connection is established between the apparatus through
the exchange of their access keys; like this, they can always exchange
information. This type of connection is the one used by the hands free
telephone systems
 Virus via Bluetooth
In recent years, and as a consequence of the growth of the Bluetooth technology, small
virus applications have appeared which allow to remote control and access the data of
telephones.

5.1 Transmitting data via Bluetooth
This kind of connection is mostly used to send data, for example a photograph, a
telephone tone or a contact from an agenda. The general way to do this is as follows:
 Step 1: The devices must have the Bluetooth service activated. To do this you must
go to the Settings menu -> Connectivity -> Activate Bluetooth in both devices.
 Step 2: Select the files you wish to send and in the Options menu choose Send ->
Via Bluetooth. A list of paired devices to select from will appear (remember that the
range of these devices are around ten metres). The destination device must accept
the request to complete the transmission.

5.2 Transmitting data via infrared
The procedure is similar to the Bluetooth although it works with other kinds of
frequencies. It is used to connect devices which are one or two metres away and have
their infrared transmitter with a visual contact at an angle less than 30° (they work with the
same principles as remote controls for televisions); and the option in the devices must be
activated.
Although not all mobile phones have infrared transmitters available, there are devices
in the market which can connect to USB ports or earphone Jacks to convert your
telephone in a complete remote control device which can control all the household
appliances.
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Things to remember!!

 Networks: Types & uses
 A computer network: What is it? What is its aim?
 Types of computer networks
 Topology of networks
 Network connections
 The devices used to form a network
 Wireless connections
 Bluetooth & Infrared
 Security in your Computer
 What does it refer to?
 Main threats
 Applications to fight these threats

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 How to make a Network Cable
This will show you how to make a RJ-45 network connector to use with a switch device.
You will need unshielded twisted pair cables cut to the necessary length (never more than
90m) category 5 or CAT5, two RJ-45 connectors, an RJ-45 crimping tool, scissors and an
RJ-45 cable tester.
Purchasing fully made Ethernet cables can be quite expensive. It
is far easier to simply buy a box of bulk Category 5 Ethernet cable
and then attach your own RJ-45 connectors to the cut ends to
your preferred length.

Bulk Ethernet cable

RJ-45 connectors

RJ-45 Crimping tool

There are two kinds of Ethernet cables you can make: Straight Through and Crossover.
STRAIGHT THROUGH - Ethernet cables are the
standard cable used for almost all purposes. The
purpose is to connect the computer to a switch or
hub. It is highly recommend you duplicate the color
order as shown on the left. Note how the orange pair
is not side by side as are all the other pairs. This
configuration allows for longer wire runs.
CROSSOVER CABLES - The purpose of a Crossover
Ethernet cable is to directly connect one computer to
another computer (or device) without going through a
router, switch or hub.
Here's how to make a standard cable:
 Cut into the plastic sheath 1 inch (1,5 cm) from the end of the
cut cable. The crimping tool has a razor blade that will do the
trick with practice.
 Unwind and pair of the similar colors.

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 Pinch the wires between your fingers and straighten them
out as shown.
The wire colors line up to form a straight through standard
cat 5 cable as described above.)
(We apologize that this picture on the left is not the exact
same color order as the picture above showing straight
through cables. Please use the color combinations above
and we will replace this photo soon.)
 Use scissors to make a straight cut across the wires 1/2 Inch from the cut sleeve to the
end of the wires.
 Push the wires into the connector. Note the position of the blue
plastic shielding. Also note how the wires go all the way to the end.
 A view from the top. All the wires are all the way in. There are no
short wires.
 WRONG WAY - Note how the blue plastic shielding is not inside the
connector where it can be locked into place. The wires are too long.
They should be 1/2 inch from the sleeve.
 WRONG WAY - Note how the cables do not go all the way to the end of
the connector.
 CRIMPING THE CABLE ... carefully place the connector into the
Ethernet Crimper and cinch down on the handles tightly. The copper
splicing tabs on the connector will pierce into each of the eight wires.
There is also a locking tab that holds the blue plastic sleeve in place
for a tight compression fit. When you remove the cable from the
crimper, the cable is ready to use.
 For a standard cable, repeat all steps on the other end of the Ethernet
cable exactly. For a cross-over cable, make sure to get the color order
right.
 Make sure to test the cables before installing them. An inexpensive
Ethernet cable tester does this quite well.

Also have a look at: http://www.wikihow.com/Make-a-Network-Cable

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 Set up a wifi router
In the following tutorial you will learn to access the router from your network so that
you can set it up correctly by changing the password it comes with, activating the
DHCP server and establishing the wireless network parameters. This tutorial has been
prepared using as a model the Thompson wireless router. Although the functioning is
similar with all, you can get more detailed information of other models in the webpage
http://www.adslzone.net.
Step 1:
Connect the computer to the router using the network cable and open Internet
Explorer (or your Internet browser if different). In the address bar type in the IP
address of the router (Default gateway). In our case 192.168.0.1.
Step 2:
Write the username and password of the router. If you haven’t changed it or if you
reset the router it will set to the default values it came with; for example, “admin” as
username with no password or “1234” as username and password for Movistar.
This will take you to the menu of the router.
Step 3:
In the different menus you can change some of the parameters. In Status ->
Password change the password that you have just used.
Step 4:
Activate the DHCP server so that when you access Network -> LAN it
automatically assigns you the network address.
Step 5:
Check the IP address with the one the router users for Internet and the DNS server
it uses in Network -> WAN.
Step 6:
Set up the ports of the router to give access to specific applications because by
default the router has most of its ports closed. If you wish to use P2P software
such as emule, torrent, etc., a number of ports must be opened and set them up in
those programs. This is done via Advance menu -> Forwarding.
Step 7:
The parental control will filter those webs which include word that you have
specified. Parental Control menu -> Basic.
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Step 8:
The wireless network parameters are modified in the Wireless menu. It is important
the name of the network so that you can connect later on. You can also change the
channel number if you see that there is a lot of interference.
Step 9:
The password of the wireless network is important to avoid intruders who can
reduce our bandwidth. To change the password, go to Wireless -> Security.
Nowadays the WEP encryption of our password is not completely safe because
there are programs that are capable of decoding them. It is advisable to use WPA
and WPA2 type encryptions if your router allows it.
Step 10:
It may be the case that your router acts as a bridge or access point in a wireless
network with several access points. If this is the case, the IP addresses of the
different wireless access points which are in the network must be set up. This
configuration is found in the Wireless menu -> Bridge.
You must confirm all the changes you carry out in each window using the Apply or
Save Settings button of each menu.

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 On-line antivirus
One of the most demanded services by Internauts today is related to security in our
computer system. As a result of this demand, many web applications have emerged
which can scan any malware in our hard disk without having to install them in our
computer. One of the most used on-line antiviruses is Panda Activescan. If you
access this webpage click on Free Scan of your computer and go to the next page. In
this window you can choose the type of analysis you wish to carry out: quick or
complete. Finally, click on the Scan button for it to start working.

COMPETENCY EVALUATION TASK:
Article:

Troyan viruses could hack your car using Bluetooth

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