Transcript Chapter 7

Practical PC, 7th Edition
Chapter 7: Connecting to the Internet
Connecting to the Internet
• FAQs:
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How does the Internet work?
What should I know about Internet service?
What are my options for Internet service?
How do local area networks offer Internet access?
How do I connect to the Internet from a local area
network?
– How does firewall software protect my computer from
intrusions?
– How does encryption protect my computer from
intrusions?
• Technology: TCP/IP
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How does the Internet work?
• The Internet is a global network of computers
– Connects millions of smaller networks, computers,
and other devices
– Not owned or operated by any single corporation
or government
– Maintained by network service providers (NSPs)
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AT&T
British Telecom
Sprint
Verizon
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How does the Internet work?
– NSP equipment and links are tied together by
network access points (NAPs)
• NAPS supply Internet connections to Internet service
providers such as EarthLink, AOL, and Comcast
– An Internet service provider is a company that
offers Internet access to individuals, businesses,
and smaller ISPs
– Data is exchanged using TCP/IP, which is a protocol
that divides information into packets of data
• Packets are sent to their destinations through routers
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How does the Internet work?
– Every device connected to the Internet has a
unique IP address
• It is a long string of numbers
• To make it easier for users, many Internet servers also
have an easy-to-remember name, i.e., nike.com
• The official term for this name is a fully qualified
domain name (FQDN) but most people just call it a
domain name
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How does the Internet work?
– Domain names end with an extension that
indicates its classification
Figure
7-1
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What should I know about Internet
service?
• Internet services vary in cost, speed, and
reliability
• Capacity of an Internet connection is referred
to as bandwidth
– Measured in bits per second
– Range from 56 Kbps (56,000 bits per second) to
100 Mbps (100 million bits per second) or more
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What should I know about Internet
service?
• Connection speed tells how fast data travels
– Measured in milliseconds (ms)
– Lower numbers indicate faster speeds
• Best for playing online games, using voice over IP,
watching online videos, and participating in Web
conferences
• Symmetrical connections
– Data travels upstream from your computer to the
Internet at the same speed as it travels
downstream from the Internet to your computer
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What should I know about Internet
service?
• Asymmetrical connections
– More common
– Data travels faster downstream than upstream
– Downstream speed is important because most
users have more information coming to their
computers than going from their computers
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What are my options for Internet
service?
• Cable Internet service
– Uses same infrastructure as cable television
– Offers fastest access speeds
– Uses a cable modem
– Usually offered in a monthly subscription
• DSL (digital subscriber line)
– Broadband that runs over standard phone lines
– Offers fast, affordable connections
– Can be symmetrical or asymmetrical
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What are my options for Internet
service?
• Dial-up Internet service
– Uses a voiceband modem and telephone lines
– Typically less than $10/month
– Access speed is slow
– Not suitable for playing games or watching videos
• Satellite Internet service
– Distributes asymmetric access via a personal
satellite dish
– In rural areas may be only choice other than dialup
– Susceptible to bad weather and slow signal time
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What are my options for Internet
service?
• WiMax
– One of the newest technologies
– Limited availability
– Transmits data to nearby communication tower
• Mobile broadband
– Access is through high-speed cellular technology,
referred to as 3G and 4G
– Used for smartphones, laptops, notebooks,
tablets, and netbooks
– Can have slower speeds, dropped connections
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How do local area networks offer
Internet access?
• Local area networks (LANs) connect
computers in a very small geographical area,
most often within the same building
• LAN’s router is connected to cable Internet or
DSL and passes Internet access to computers
connected to the LAN
– Ethernet
• Fast and secure wired network technology
• Popular with businesses, school computer labs and
home networks
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How do local area networks offer
Internet access?
– Wi-Fi (or WiFi)
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Popular wireless technology
Transmits data using radio waves
Slower and less secure than Ethernet
WiFi hotspot is a wireless network used by coffee
shops, hospitals, airports, libraries, and school
campuses to provide access to guests using laptop
computers or mobile devices
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How do local area networks offer
Internet access?
• To access the Internet using a
local area network, connect to
the LAN
– Windows automatically senses
nearby networks and displays
their SSIDs
– Some networks are secured;
others are open to the public
• To connect to a secure network, a
correct encryption key must be
entered
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How do local area networks offer
Internet access?
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How do local area networks offer
Internet access?
Figure
7-6
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Hardware: Wired and wireless
network devices
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How does firewall software protect my
computer from intrusions?
• An intrusion is any access to data or programs
by hackers, criminals, or other unauthorized
persons
• Access can be gained through an open port
– A port is any pathway of data in or out of a
computer
– Port scanning software looks for unprotected
computers and can attack an unprotected
computer within four minutes
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How does firewall software protect
my computer from intrusions?
• Firewall software
– Makes sure incoming information was actually
requested and is not an unauthorized intrusion
– Blocks activity from suspicious Internet addresses
– Reports intrusion attempts
– Essential for computers connected directly to the
Internet
• Windows system includes Windows Firewall
• Only one firewall should be active at any given time
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How does firewall software protect
my computer from intrusions?
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How does encryption protect my
network from intrusions?
• Wireless signals can be picked up by any
device within the network coverage area,
including hackers
– WEP was the original wireless encryption
• Provides level of confidentiality similar to that of a
wired network
• Very easy to bypass
• Does protect from casual hacks and inadvertent cross
talk from nearby networks
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How does encryption protect my
network from intrusions?
– Newest versions of encryption make sure that
packets have not been intercepted or tampered
with in any way
• WPA and WPA2
• PSK
– Encryption keys are created when wireless
encryption is set up
• Anyone wishing to join the network must key in the
encryption key
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How does encryption protect my
network from intrusions?
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Technology: TCP/IP
• TCP/IP
– Primary protocol suite responsible for message
transmission on the Internet
– Protocol suite
• Combination of protocols that work together
– TCP breaks a message or file into packets
– IP is responsible for addressing packets so they
can be routed to their destination
– TCP/IP is public, free, extensible, and easy to
implement
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Technology: TCP/IP
• Circuit switching
– Used by early communications networks
– Established dedicated links between two
communicating parties, i.e., establishing a private
link between two telephone lines
– Practically, it is inefficient
• Packet switching
– Divides messages into several packets
– Packets can be routed independently
– More efficient than circuit switching
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Technology: TCP/IP
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Technology: TCP/IP
• IP addresses
– Originated on Internet as part of the TCP/IP
protocol
– Used to uniquely identify computers on the
Internet and on LANs
– Two kinds
• IPv4 – addresses are divided by periods into four
segments
• IPv6 – numbers are divided by periods into eight
segments
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Technology: TCP/IP
– When connected to the Internet through a router
or LAN, the IP address of the computer can be
different from the address used for the Internet
connection
• Shields computer from intrusion attempts
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Technology: TCP/IP
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What is an IP address?
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