chapter three peripherals and networking part ii: networking

Chapter Three

Peripherals and NetworkingPart II: Networking

© 2006-2011 Wiley, Inc. All Rights Reserved.

Strata Objectives Covered

1.1 (1.1 FC0-U11 U.K.) Identify basic IT vocabulary– Networking

2.1 (1.1 FC0-U21 U.K.) Identify basic compatibility issues between

– Ethernet– Wireless networks

3.1 (1.1 FC0-U11 U.K.) Recognize basic security risks and procedures to prevent them

– Identify prevention methods: Wireless Encryption (WPA/WEP)

2


What is a Network?

• Two or more computers connected to share data and resources

• Resources shared may include:– Files and folders– Disk drives– Applications– Printers– Internet connections

3


Clients and Servers

• Server: A PC that exists only to route network traffic and provide access to shared files and printers

• Client: An ordinary PC that an end-user employs

4


Clients and Servers

• Client/Server network: A network that contains at least one server

5


Clients and Servers

• Peer-to-Peer network (P2P): A network that consists only of clients

6


Local and Wide Networks

• Local Area Network (LAN): A network where the computers are all located physically close together, such as in the same building

• Wide Area Network (WAN): A network where the computers are physically far apart from one another

• Metropolitan Area Network (MAN): Computers are all in the same city

7


Ethernet

• The most popular networking technology

• Early competitors, now obsolete, included Token Ring

• Although Ethernet is most often known as a wired technology, it is also available in wireless form (Wi-Fi)

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Ethernet Hardware

• Network adapter (also called network interface card, or NIC)

• Switch, router, or other connection point

• Network cables (if not wireless)

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Network Adapters

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• Various types– Built into motherboard– Expansion board– External USB device

• To identify a wired model, look for an RJ-45 jack– Looks like an extra-wide phone jack


Network Adapters

• To identify network adapter model and type, look in Device Manager in Windows

11


Routers and Switches

Connection boxes with multiple cable jacks (or wireless connection capability)•Switch: takes in traffic from various connections and directs the data to the appropriate outward-bound lane•Router: smarter version of a switch, able to direct traffic intelligently out to other connected networks

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Routers

• Used on the Internet to route and control data traffic

• Used in a home or small business to enable multiple PCs to share a single Internet connection

• Used in large business networks to direct traffic between network segments, such as different departments

13


Ethernet Cables

• Unshielded twisted pair (UTP)– Multiple pairs of wires in the cable (usually 4

pairs)

– Each pair of wires is twisted to minimize electromagnetic interference (EMI) between the wires

– Called unshielded because the cable’s outer coating does not provide protection against EMI.

• Shielded twisted pair (STP)– A variant of UTP that includes EMI shielding

14


Ethernet Cabling

• Most common connector type is RJ-45 jack; RJ stands for Registered Jack

• RJ-45 contains 8 wires (four pairs)

• There are other RJs:– RJ-11: Single-line telephone

connector, containing two wires– RJ-14: Dual-line telephone

connector, containing four wires

15


Cable Categories

• UTP quality, and ability to carry a signal reliably, is rated by category numbers

• Choose a cable category depending on the network speed required– Category 5 (Cat5): up to 100 Mbps– Cat5e: up to 1 Gbps– Cat6: up to 10 Gbps

16


Standard and Crossover Cables

• Relationship of the wires at one end of the connector to the other is its pin-out.

• Standard cables are the same at both ends

• A crossover cable reverses the order of the wires in one end

• Crossover cables are used to connect two similar devices

17


Powerline Ethernet

• Also called HomePlug technology • Uses electrical wiring in a home or

business to carry Ethernet data• Predates the availability of wireless

networking; now uncommon

18


Wi-Fi

• Wireless Fidelity • Common name for wireless Ethernet• Standard controlled by Institute of

Electrical and Electronics Engineers (IEEE)

19


Wi-Fi Standards

Standard Frequency Top Speed Range in Meters (Indoors/Outdoors)

802.11a 5 GHz 22 Mbps 15/34

802.11b 2.4 GHz 11 Mbps 46/92

802.11g 2.4 GHz 22 Mbps 46/92

802.11n 2.4 and 5 GHz 600 Mbps 70/250

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Wi-Fi Hardware

• Wireless network adapter• Wireless router• Wireless access point (WAP)

– Wireless version of a switch

21


Network Speed Negotiation

• Networks auto-negotiate transmission speed based on the lowest-capability device involved in the communication

• For example, 802.11b device can communicate with 802.11n device, but both will be limited to 802.11b speed

22


Network Duplex Negotiation

Duplexing is the ability of devices to both talk and listen at the same time

– Simplex: one-way communication only– Half-duplex: two-way communication

but only one direction at a time– Full duplex: two-way communication

simultaneously

23


Wireless Network Settings

• Service Set Identifier (SSID)– Name by which the WAP is

known on the network– If you broadcast the SSID,

anyone can see the router and try to connect to it

– If you do not broadcast the SSID, the network is harder to locate, and therefore harder to break into

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Wireless Network Encryption

• Prevents computers from connecting to the router if they don’t have the correct password

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• Wired Equivalent Privacy– Older but still used– 128-bit or 256-bit encryption key– Authentication methods:

• Open Source authentication• Shared Key authentication

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• Wi-Fi Protected Access (WPA)– Newer, flexible, more secure than WEP– WPA-Personal

• Similar to WEP in terms of setup

– WPA-Enterprise• Requires an authentication server• Designed for large networks

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• Encryption protocols:– Temporal Key Integrity Protocol (TKIP)– Computer Mode with Cipher Block

Chaining Message Authentication Code Protocol (CCMP)

28


Bluetooth

• Short-range wireless networking• Separate from Wi-Fi, also known as

IEEE 802.15• Used with many types of devices

– Cell phones– Home theatre devices– Gaming consoles– Cordless headsets– Cordless keyboards and mice– GPS devices

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Bluetooth

• Designed for a one-to-one connection, such as between a computer and a peripheral

• Classes:– Class 1, 1Mbps,

1 meter distance– Class 2, 3 Mbps,

10 meter distance– Class 3, 24 Mbps,

100 meter distance

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Networking Protocols

• Protocol: A set of communication rules between two devices or two points in a process

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TCP/IP

• Transmission Control Protocol / Internet Protocol

• The most widely used protocol• An interconnected set of protocols,

rather than a single one• Most LANs use it internally• The Internet uses it

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Network Addresses

• Each network device must have a unique IP address– IP address is assigned to a PC, and can

be removed or reassigned

• Each network device has a Media Access Control (MAC) address– MAC address is hard-coded into the

hardware, and cannot normally be changed

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Static and Dynamic IP Addressing

• Static IP Addressing:– IP addresses is manually configured on

the device

• Dynamic IP Addressing:– IP addresses is assigned by a Dynamic

Host Configuration Protocol (DHCP) server on a network

– Automatic Private IP Addressing (APIPA) enables Windows to assign an IP address within a certain range if it can’t locate a DHCP server

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IP Address Versions

• Currently IP Version 4 is prevalent– Four numbers, each between 0 and 255,

separated by periods– Example: 204.52.0.23

• The Internet will at some point switch to IP Version 6 – Eight four-digit hexadecimal numbers,

separated by colons– Example:

4FFE:190C:4545:0200:F8FF:FA21:67CF

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Network Address Translation

• Routers can use Network Address Translation (NAT) to change the IP address on a data packet

• NAT enables multiple computers on a LAN to share a single Internet connection– Outgoing data appears to come from

the router, not from the individual PCs– Incoming data is directed to the

appropriate individual PC by the router

36


TCP Ports

Protocol Port

FTP 20 and 21

HTTP 80

HTTPS 443

POP3 110

SMTP 25

IMAP 143

DHCP 67 and 68 (IPv4)546 and 547 (IPv6)

DNS 53

37


Dial-Up Modem

• Short for modulator-demodulator• Analog-to-digital and digital-to-

analog converter and transmitter• Uses telephone lines• Very old and slow (limited to 56Kbps)

38


Broadband Internet Types

• Digital Subscriber Line (DSL)– Works through phone line, with DSL

modem (terminal adapter)– Requires a certain proximity to

telephone central office (CO)– Speed and quality depend on proximity

to CO– Symmetric: uploads and downloads

same speed– Asymmetric: downloads faster than

uploads39



• Cable– Works through cable TV lines– Shared bandwidth with local neighbors– Typically faster than DSL– Requires cable modem

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• Satellite Internet– Available almost anywhere– Slower and more expensive than DSL or

cable– Requires satellite dish and terminal

adapter– Weather conditions may affect service

41


DNS Servers

• Domain Name System (DNS) servers translate between numeric IP addresses and text-based URLs

• Top-level DNS servers route requests to appropriate second-level server (for com, net, org, and so on)

• Domain name assignments are managed by InterNIC

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HTTP and HTTPS

• Hypertext Transport Protocol (HTTP) is the basic unsecured protocol used for most web traffic

• Hypertext Transfer Protocol Secure (HTTPS) is a secure version of HTTP– Combines regular HTML with Transport

Layer Security (TLS) or Secure Sockets Layer (SSL) security

43


HTTPS Security

• Ensures the identity of the web site via security certificate

• Certificates are registered with a certificate authority such as VeriSign

• TLS or SSL is used to encrypt the data

44


Mail Protocols

• Post Office Protocol 3 (POP3)– Handles incoming e-mail– Works with e-mail apps such as Outlook – Store-and-forward system

• Simple Mail Transport Protocol (SMTP)– Handles outgoing e-mail– Works with e-mail apps such as Outlook – Store-and-forward system

45


Mail Protocols

• Internet Mail Access Protocol (IMAP)– Works with email apps such as Outlook– Mail is managed from the server– Mail can be accessed only when

network connectivity is available– IMAP handles both incoming and

outgoing mail

46


FTP

• File Transfer Protocol• A very old protocol, predating the

Web• Used to transfer files to and from file

servers• Addresses begin with ftp://• You can use a Web browser or an

application designed for FTP

47


VoIP

• Voice over IP• A set of applications, technologies,

and protocols• Provides IP-based telephone

services

48


Web Browser Add-Ons

• Also called plug-ins• Helper program for a browser that

increases its capabilities– Plays a certain type of data file, such as

a video clip– Runs a certain type of embedded

application

49


Browser Customization

• Font sizes and colors• Font choices• Zoom percentage• Toolbars and status bars• Privacy tools• Security tools

50


ActiveX

• Uses Microsoft .NET programming framework

• Enables a web browser to interact with the OS to run mini-applications (ActiveX controls)

• Two parts: the browser plug-in, and the individual ActiveX controls at Web sites

51


Java

• A programming language• Works across multiple platforms• Often used as an alternative to

ActiveX to create web apps• Browser must support Java or have

an appropriate add-in• Java is somewhat safer than ActiveX

because it works within a virtual machine (VM)

52


Cookies

• Small plain-text files that web pages use to store data on your hard disk

• Allow web browsers, which are normally stateless, to remember information needed to make certain types of content work– Shopping– Gaming– Social networking

53


Cookies

• First-party cookie: cookie from the main site you are visiting

• Third-party cookie: cookie from an ad on the site

• Persistent cookie: cookie that stays when you close the browser

• Session cookie: cookie that is deleted when you close the browser

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chapter three peripherals and networking part ii: networking

Documents

network adapters

network segments

networking slide

route network traffic

network adapter model

servers clientserver

peer network p2p

network interface card