Chapter 3
Chapter 3 Objectives
Communications and Network terminology and applications Various communications devices, media, and proceduresType of Computer Networks
Describe the types of
computer-network & Internet security risks
Communications
•
What are computer
communications
?
Communications
• What is needed for successful communications?
•Initiates instruction to transmit data, instructions, or information. Commonly in software forms
Sending device
•Connects the sending device to the communications channel Communications device
•Media on which data, instructions, or information travel
Communications channel
•Connects the communications channel to the receiving device Communications device
•Accepts transmission of data, instructions, or information
Communication Software
•
What is
communications software
?
Programs that help users establish connection to Internet, other network,
or another computer Programs that help users manage transmission of data, instructions,
and information
Communication Devices
•
What are examples of communications
devices?
Common types are [dial-up modems, ISDN & DSL modems, broadband/cable modems] For
Internet Communication, and [network cards, wireless access points, routers, and
Communication Devices
•
What is a
modem
?
• Converts digital signals to analog signals and vice versa
• Notebook computers often use PC Card modem
Dial Up Modems
Cable and Wireless Broadband Modems
Communications Devices
•
What is a
network card
?
– Adapter card, PC Card, or compact flash card that enables computer or
device to access network
Communications Devices
•
What is a
wireless access
point
?
– Central communications device that allows
Communications Devices
•
What is a
router
?
– Connects computers and transmits data to correct destination on network
– Routers forward data on Internet using fastest
Communications Devices
•
What is a
switch/hub
?
– Device that provides
Communications Channel
•
What is a
channel
?
– Transmission media on which data travels in communications system
Transmission media
are materials
capable of carrying one or more signals
Bandwidth is amount of data
Transmission Media
Physical
• Optical Fiber
• Twisted Pair Cables
• Coaxial Cable
Wireless
• Communications Sattelite
• Microwave Radio
• Cellular Radio (2G, 2,5G, 3G, etc)
• Broadcast Radio (Wi-fi, Bluetooth)
Computer Network
•
What is a
network
?
– Collection of computers and devices connected via communications devices and
Computer Network
•
What is a
local area
network (LAN)
?
– Network in limited
geographical area such as home or office
building
– Metropolitan area network (MAN)
Computer Network
•
How to Join a computer into a LAN
Computer Network
•
What is a
wide area
network (WAN)
?
– Network that covers large geographic area using many types of media
– I ter et is world’s
Computer Network
•
What is a
client/server
network
?
– One or more computers act as server and other
Computer Network
•
What is an
Intranet
?
Internal network that uses Internet technologies
Makes information accessible to employees
Typically includes connection to Internet
Extranet allows customers or suppliers to access
Computer Security Risks
•
What is a
computer security risk
?
– Action that causes loss of or damage to computer system
– Mostly happened when computer connected into a network
Computer Viruses, Worms, and Trojan Horses
•
What are
viruses, worms
, and
Trojan horses
?
Virus is a potentially damaging computer program Worm copies itself repeatedly, using up resources and possibly shutting down computer or network
Trojan horse hides within
or looks like legitimate program
until triggered
Payload (destructive event) that is delivered when you open file, run infected program, or
boot computer with infected disk
in disk drive
•
How can a virus spread through an
message?
Step 1. Unscrupulous programmers create a virus program. They hide the virus in a Word document and attach the Word document to an e-mail message.
Step 2. They use the Internet to send the e-mail message to thousands of users around the world.
Step 3b. Other users do not recognize the name of the sender of the e-mail message. These users do not open the e-mail message. Instead they delete the e-mail message.
These users’ computers are not
infected with the virus.
Step 3a. Some users open the attachment and their computers become infected with the virus.
•
What are some tips for preventing virus,
worm, and Trojan horse infections?
Install a personal firewall program If the antivirus
program flags an e-mail attachment as infected, delete
the attachment immediately
Never download or install suspicious
software from untrusted sources
Never open an e-mail attachment
unless you are expecting it and
it is from a trusted source Install an antivirus
program on all of your computers
Check all downloaded programs for viruses, worms, or Trojan horses
DOS & Backdoor
•
What is a
denial of service (DOS)
attack and
back door
?
A denial of service attack is an assault which disrupts computer access to an Internet service
such as the Web or e-mail
A back door is a program or set of instructions in a program that allow users to bypass security controls when accessing a computer
Spoofing
•
What is
spoofing
?
Makes a network or Internet
Transmission appear legitimate IP spoofing occurs when an intruder computer fools a network into believing
its IP address is from a trusted source
Perpetrators of IP spoofing trick their victims into interacting
Solutions
•
Best way to prevent
spoofing
and
DOS
is to
build a
firewall
Solutions
•
What is
firewall
?
Solutions
•
What is
personal firewall
?
– Program that protects personal computer and its data from unauthorized intrusions
– Monitors transmissions to and from computer
Unauthorized Access and Use
•
Unauthorized Access
– Use of a computer or network without permission.
– By connecting to it and then logging in as a legitimate user.
– Do not cause damages.
– Merely access the data, valuable information or programs in the computer.
– In some manners, can be categorized as
•
Unauthorized Use
– Use of a computer or its data for unapproved or illegal activities.
– Ex: gaining access to a bank computer and
performing an unauthorized bank transfer etc.
Solutions
•
How to prevent unauthorized access and use?
Solutions (Cont.)
•
How to make good passwords?
GOOD
• Example:
@k|_|-@n@6-4L4Y
• Longer, alay-er, better
NEVER USE IT
• Your birth-day
• Your mother/dad/lover name
• Very predictable words
• Plain, not combinated characters is weak against
Solutions (Cont.)
•
How to prevent unauthorized access and use?
– Disable file and printer sharing on Internet connection
– enable just
when you need it
Solutions (Cont.)
•
How to ake i for atio thief life’s u h
harder?
– Use encryption
• Safeguards against information theft
• Process of converting plaintext (readable data) into
ciphertext (unreadable characters)
• Use key to generate cipherkey as combinations
• To read the data, the recipient must decrypt, or
decipher, the data
Internet Security Risk
• Information Sniffing, How?
• H or L can get all sensitive un-encrypted information
Username, Passwords,
Credit card’s details
Internet Security Risk
• Website phising, How?
https://ib.bankmandiri.co.id/retail/Login.do?action=form https://ib.bangmandiri.co.id/retail/Login.do?action=form
Impersonated Login Page
Ba k Ma diri’s
Server Username, Passwords,
Credit card’s details
Cra ker’s Co puter
Internet Security Risk
• Website phising commonly spread using emails and social media
Internet Security Risk
• Social engineering is an non-technical, outside hacker's use of psychological tricks on
legitimate users of a computer system, in order to gain the information (usernames and passwords) one needs to gain access to the system.
• It utilizes two human weakness:
– no one wants to be considered ignorant
Solutions
•
Web browsers provide secure data
transmission
Many Web browsers use encryption
Secure site Choose Web site that
uses encryption to secure data
Valid Digital certificate Guarantees Web site
Solutions
•
Provides encryption of
all data that passes
between client and
Internet server
– Web addresses
egi i g with https
Solutions
• Protect yourselves from social engineering
– Be educated, aware, and a little bit paranoid.
– Never give out:
• Usernames / ID numbers
• Passwords / PIN numbers
• System information
• Credit card numbers
• Schedules
• Other Sensitive data
