Networks Continued

What does MAN stand for?

Metropolitan Area Network

What does NAN stand for?

Neighborhood Area Network

What does LAN stand for?

Local Area Network

What does WAN stand for?

Wide Area Network

What does PAN stand for?

Personal Area Network

Name that topology!

Tree

Topologies, such as the Ring Topology, can have redundancy built in so that if one node fails data can travel an alternate route to the destination

5 Network Links

 A communications channel, or link, is a physical path or frequency for signal transmissions  Bandwidth is the transmission capacity of a communications channel – – Broadband Narrowband

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5 Communications Protocols

 A packet is a “parcel” of data that is sent across a computer network – Circuit-switching technology vs. packet switching technology

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Circuit Switching

• Dedicated communication path between two nodes • Inefficient • Path capacity dedicated for duration of connection • example: telephone system

Packet Switching

• efficient • Single node to node link can be shared by many packets over time • example: internet

5 Communications Protocols

 Rules for efficiently transmitting data from one network node to another – – Divide messages into packets Affix addresses to packets – – – – Initiate transmission Regulate flow of data Check for transmission errors Acknowledge receipt of transmitted data

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5 Communications Protocols

 Every packet that travels over a network includes the address of its destination device  A MAC address is a unique number assigned to a network interface card when it is manufactured  An IP address is a series of numbers used to identify a network device  IP addresses can also be obtained through DHCP

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DHCP

Stands for Dynamic Host Configuration Protocol It is an auto-configuration protocol used on IP networks. Computers that are connected to IP networks must be configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a network administrator. It also provides a central database for keeping track of computers that have been connected to the network. This prevents two computers from accidentally being configured with the same IP address

Name that topology!

Bus

5 Wired Network Basics

 A wired network uses cables to connect network devices  Wired networks are fast, secure, and simple to configure  Devices tethered to cables have limited mobility

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5 Ethernet

 Simultaneously broadcasts data packets to all network devices – – IEEE 802.3

CSMA/CD protocol  Vary in speed from 10Mbps to 100Gbps

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Ethernet

• is the most widespread wired LAN technology

5 Ethernet Chapter 5: LANs and WLANs

On an Ethernet, data travels on a first-come, first-served basis. If two workstations attempt to send data at the same time, a collision occurs.

That data must be resent.

20

5 Ethernet Equipment Chapter 5: LANs and WLANs 21

5 Ethernet Equipment

 Ethernet adapter (designed to support the Ethernet protocols)  Network hub  Network switch  Network router  RJ45 connector

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Hubs, Switches, & Routers

• Hub: basic networking component used to connect computers to form a LAN – a data packet coming from one port is sent to all other ports – basically organizes your cables and relays data signals to all computers on the LAN

Hubs, Switches, & Routers

• Switch: networking device that controls the flow of data by using the MAC address that is placed on each data packet – Switches divide networks into Virtual LANS (VLAN) – becoming very popular on both small and large networks

Hubs, Switches, & Routers

• Router: utilize a combination of hardware/software to actually route data from source to destination – utilizes IP addresses – divides large networks into logical segments called subnets

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5 Ethernet Setup

Most routers are configured using a browser. You should change the network administrator password, then verify that DHCP is enabled

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Name that topology!

Star

5 Wireless Basics

 A wireless network transports data from one device to another without cables or wires – RF signals • Transceiver – – Microwaves Infrared light  Slower than wired networks  Security concerns

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5 Bluetooth

 Bluetooth is a short-range, wireless network technology designed to make its own connections between electronic devices, without wires, cables, or any direct action from a user

Chapter 5: LANs and WLANs 30

5 Wi-Fi Equipment

 If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi card

Chapter 5: LANs and WLANs 31

5 Sharing Files

 If you use Windows, it automatically detects available LANs any time you turn on a workstation  To connect to a shared resource, you might be asked for a user ID and password

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5 Troubleshooting

 Network problems can stem from a variety of sources – Cables – – Signal strength Security – – – Interference Network devices Settings

Chapter 5: LANs and WLANs 33

Name that topology!

Mesh

Security

5 Wi-Fi Security

 Wireless networks are much more susceptible to unauthorized access and use than wired networks  LAN jacking, or war driving, is the practice of intercepting wireless signals by cruising through an area

Chapter 5: LANs and WLANs 36

5 Wi-Fi Security

 Wireless encryption scrambles data transmitted between wireless devices and then unscrambles the data only on devices that have a valid encryption key – – – – WEP (Wired Equivalent Privacy) WPA (Wi-Fi Protected Access) WPA2 PSK  Activate encryption by using a wireless network key

Chapter 5: LANs and WLANs 37

5 Encryption

 Encryption transforms a message so that its contents are hidden from unauthorized readers – Plaintext has not yet been encrypted  Decryption is the opposite of encryption – – Cryptographic algorithm Cryptographic key

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5 Encryption

 Weak vs. strong encryption  AES (Advanced Encryption Standard) – standard adopted by the U.S. government  Encryption methods can be broken by the use of expensive, specialized, code-breaking computers – Brute-force method

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5 Encryption

 Public key encryption (PKE) eliminates key-distribution problem, by using one key to encrypt a message and another key to decrypt the message

Chapter 5: LANs and WLANs 40

PKE (Public Key Encryption)

• You can think of it as a locked front door to a building, and the door has a mail slot – Mail slot is exposed and accessible to the public; its location (street address) is like the public key – Anyone knowing the address can go to the door and drop a message through the slot – Only the person possessing the matching private key (owner of the building) can open the door and read the message

War Driving

• the act of searching for wireless networks by a person in a moving vehicle using a portable computer or PDA Story on war driving: http://www.fbi.gov/news/stories/2004/nove mber/war_spammer111004

HTTPS

You may have seen HTTPS at the beginning of the URL while doing online shopping, banking, etc. HTTPS stands for Hypertext Transfer Protocol Secure It utilizes the SSL/TLS protocol to provide encrypted communication and secure identification of a network web server

Name that topology!

Ring