Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
1
Technology in Action
Chapter 12
Behind the Scenes:
Networking and Security
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
2
Networking Advantages
• Networks
– Increase productivity
– Enable the sharing of hardware resources
– Facilitate knowledge sharing
– Enable the sharing of software
– Facilitate Internet connectivity
– Enable enhanced communication
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
3
Client/Server Networks
• Server-based network
– Clients and servers
• Data flows efficiently
• Servers respond to
requests from clients
• Servers perform
specific tasks
• Scalable
• Centralized
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
4
Classifications of
Client/Server Networks• LAN
– Local area
network
– Computers
linked over
a small
geographic
region
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
5
Classifications of
Client/Server Networks• WAN
– Wide area network
– Computers linked over large geographic locations
• MAN– Metropolitan
area network
– Computers linked within a city or county
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
6
Classifications of
Client/Server Networks
• PAN
– Personal area network
– Wireless devices connected in close proximity
to each other
• Intranet
– Private corporate network
– Protected by a firewall
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
Classifications of
Client/Server Networks
• Extranets
– Only certain corporations or individuals can
access
– Useful for enabling electronic data
interchange
– Use virtual private networks (VPN) for security
added security measures
7Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
8
Constructing
Client/Server Networks• Servers
• Network topologies
• Transmission media
• Network operating
system (NOS)
software
• Network adapters
• Network navigation
devices (routers)
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
9
Servers
• Number and types of servers depend on
network size and workload
• Dedicated servers: (described below)
– Perform one specific function
• Authentication servers
– Keep track of network logins and services
available
• File servers
– Store and manage files
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
10
Servers• Print servers
– Manage client-requested printing jobs
– Create print queue (prioritize print jobs)
• Application servers– Act as a storage area for application software
• Database servers– Provide clients with access to database
information
• E-mail servers– Process and deliver incoming and outgoing
e-mail (anti-virus, anti-spam, anti-spyware, firewall)
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
11
Servers
• Communications servers
– Handle communications between networks,
including the Internet (firewall, anti-hacking)
– Often the only device on the network directly
connected to the Internet
• Web servers
– Host a Web site available through the Internet
– Markup pages, interaction with user
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
12
Network Topologies
• The physical or logical layout of
computers, transmission media, and other
components
• Types of network topologies
– Bus topology
– Ring topology
– Star topology
– Hybrid topology
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
13
Bus Topology
• All nodes are connected in sequence on a single cable
• Used most often in peer-to-peer networks
• Networked computers communicate with each other
• One computer transmits data at a time– Access methods avoid data
collisions
– Data is transmitted in packets
– 512-1024 bytes
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
14
Ring Topology
• Nodes are laid out in a ring.
• A token (data packet) flows in one direction from device to device.
• Recent versions have data transfer rates of up to 100 Mbps.
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
15
Star Topology
• Nodes connect to a central
communications device
(switch or hub).
• A node sends a signal to
the switch, which
retransmits it to the
destination node only.
• Hub-sends to all nodes
• A node accepts only
signals addressed to it (?).Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
16
Avoiding Data Collisions
on an Ethernet Network
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
17
Transmission Media
• The routes data takes to flow between
devices on a network
• Wired
– Twisted pair
– Coaxial
– Fiber-optic
• Wireless
• -usually microwave, could be RF
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
18
Choosing a Cable
• Maximum run length
• Bandwidth
• Bend radius
• Cable cost
• Cable and installation costs
• Susceptibility to interference
• Signal transmission methods
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
19
Twisted Pair Cable
• Pairs of copper wire
twisted around each other
• Twists make the wires less
susceptible to interference
• Shielded twisted pair (STP)
– Layer of foil shielding
• Unshielded twisted pair
(UTP)
– Cat 5E: Bandwidth 200 Mbps
– Cat 6: Bandwidth 1 Gbps
– No foil layerCopyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
20
Coaxial Cable
• Four components
– Copper core
– Nonconductive insulating material
– Braided metal
– Plastic cover
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
21
Fiber-Optic Cable
• Components include
– Glass or plastic fibers
– Cladding
– Outer jacket
• Uses light impulses
to transmit data
• Immune to
interference
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
22
Wireless Media
802.11 Standard
• Wi-Fi (short for Wireless Fidelity)
– 802.11b
– 802.11a
– 802.11g
– Super G
– 802.11n
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
23
Network Operating
Systems (NOS)
• Provide the protocol that controls the
communication among devices on the
network
• Many modern OSs include NOS client
software
• Major network operating systems
– Windows Server 2008
– UNIX
– Novell Open Enterprise ServerCopyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
24
Network Adapters
• Devices that enable computers to communicate on a network
• Network interface cards (NICs)
• Three functions
– Generate network transmission signals
– Create data packets
– Act as information gatekeepers
• Ethernet compliant
• Wireless NICs
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
25
Network Navigation Devices
• Media Access Control (MAC) address– Six two-digit numbers (such as
01:40:87:44:79:A5)
– Physical address of network adapter
– Internal network identification
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
26
Network Navigation Devices
• Switches and bridges– Send data on a
specific route through the network
– Bridges send data between collision domains
• Routers– Send information
between two networks
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
27
Network Navigation Devices
• Repeaters– Amplify a signal and
retransmit it
– Extend cable runs
• Hubs– Transmit signals; have
multiple ports• Receive a signal from a
device
• Reconstruct the signal
• Transmit the signal to all ports on the hub (amplifies also)
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
28
Network Security Threats
• Human errors and mistakes
• Malicious human activity
– Current and former employees hacking or
planting viruses
• Natural events and disasters
– Hurricanes, floods, fire
– Disaster Recovery Plan
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
29
Network Security
• Firewalls
– Prevent access to the network by
unauthorized users
– Composed of software and/or hardware
– Screen and validate data packets
– Bastion host/proxy server
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall
30
Network Firewall Layout
Copyright © 2010 Pearson Education, Inc. Publishing as Prentice Hall