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Fundamentals of Networking. Discovery 1, Chapter 7. Objectives. Describe wireless technology Describe the various components & structure of a wireless LAN Describe wireless security issues and mitigation strategies Configure an integrated wireless access point and wireless client.

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fundamentals of networking

Fundamentals of Networking

Discovery 1, Chapter 7

  • Describe wireless technology
  • Describe the various components & structure of a wireless LAN
  • Describe wireless security issues and mitigation strategies
  • Configure an integrated wireless access point and wireless client
understanding wireless
Understanding Wireless
  • Electromagnetic Spectrum
    • Radio, TV, Light, X-Rays, Gamma Rays
    • Each has a specific wavelength
      • Like the distance between waves
  • Wireless uses Electromagnetic Waves
    • Same as carrying radio signals
  • We’ll discuss the most common wavelengths
infrared ir
Infrared (IR)
  • Low energy
  • Can’t go through walls, short range (30’)
    • Line of sight
  • One to one communication
    • Wireless Mice & Keyboards, Remotes, PDA
    • Infrared Direct Access (IrDA) port
ir your tv
IR & Your TV
  • Your TV remote has an infrared LED inside
  • Switches on & off to create 0’s and 1’s when you push a button
    • Push a button to send a 7 digit sequence of 0’s & 1’s
    • Sony TV Channel Up is 0000011, channel down is 0010001
radio frequency rf
Radio Frequency (RF)
  • Wireless LAN, cordless phone, Bluetooth
  • LAN & Phone
    • Signal travels through walls, longer range, higher power
    • 900 MHz, 2.4 GHz and the 5 GHz frequency
  • Bluetooth
    • Low speed, short range, lower power
    • One to many devices
    • Uses 2.4GHz
    • Starting to use Bluetooth for wireless mice, etc.
  • Bluetooth or RF. Which has higher power output?
    • RF
  • Two doctors are beaming their business cards to each other through their PDAs. Which signal is being used?
    • IR
wireless limitations
Wireless Limitations
  • Many devices use wireless
    • Cordless Phones 2.4GHz Interference
    • Microwave Ovens Interference
    • Range
    • Solid Walls a problem
  • Not as fast as, or reliable as, wired
  • Security
    • Wireless is east to access & can be intercepted
      • Authentication & Encryption now used
wpan smallest
Wireless Personal Area Network

Used to connect wireless mice, keyboards & PDA’s to computer

IR or Bluetooth

Short Range

Device to device

Peer to peer

  • Wireless Local Area Network
    • RF
    • IEEE 802.11 standards
    • Users connect to a wired network through an Access Point (AP)
    • Medium range
access point
Access Point
  • Between your wired equipment and your wireless devices
  • Wireless Wide Area Network
    • Cell phone network
    • GSM, CDMA
    • Long range
    • Government regulated
wireless standards
Wireless Standards
  • Specifies data speed, range, RF spectrum
  • IEEE standards, Wi-Fi
  • 802.11a, 802.11b, 802.11g and 802.11n
  • Wi-Fi Alliance tests devices from manufacturer
  • Will work with other devices w/ same logo
802 11b
  • 1999
  • 2.4GHz
  • 11Mbps
  • 150ft range indoors
  • 300 ft range outdoors
802 11a
  • 1999
  • 5GHz
    • Unused at that time
    • Less congestion
  • 54Mbps (faster than B)
  • NOT compatible with b/g/n
  • 75ft-150ft range
  • Originally too expensive
  • Now hard to find
802 11g
  • 2003
  • 2.4GHz
  • 54Mbps
  • 150ft range indoors
  • 300 ft range outdoors
  • Compatible with 802.11b
802 11n
  • 2.4Ghz
  • Up to 750ft range
  • Backwards compatible b/g
wireless components
Wireless Components
  • Access Point
    • Connects wireless devices to wired network
  • Client
    • Any host device that connects to wireless
    • Also known as STA (station)
  • Bridge
  • Antenna
omni directional antenna
Omni-Directional Antenna
  • Equally in all directions
  • Found on APs
directional antenna
Directional Antenna
  • Concentrate signal in one direction
  • Better distance
  • Connects networks 25 miles or more apart
  • Bridge to Bridge- connects 2 networks wirelessly
want a bridge aironet 1400
Want a bridge? Aironet 1400
  • Find it on
wlans the ssid
WLANs & the SSID
  • Your WLAN has to be identified
ssid service set identifier
SSID-Service Set Identifier
  • Tells wireless devices which WLAN they belong to & which other devices they can communicate with
  • Case-sensitive & up to 32 characters
  • All of your devices MUST have same SSID
    • Broadcast or Not?
wlan install 1 ad hoc mode ibss
WLAN Install 1:Ad-hoc Mode- IBSS
  • Wireless devices can talk to each other without involving Access Point
  • Peer-to-peer or small networks
  • Less $$$, no AP
wlan install 2 infrastructure mode bss
WLAN Install 2: Infrastructure Mode- BSS
  • Most used
  • AP/Router controls communication
    • Access to Internet
    • Basic Service Set (BSS)
      • Area covered by a single AP
cover more areas
Cover More Areas
  • Connect many BSS’s to get expanded area
    • You get an ESS, Extended Service Set
  • Areas should overlap
    • Think about this school & coverage
lab activity
Lab Activity
    • Setting the SSID on an AP
  • Click Topology, then the host
  • View browser, follow directions
wireless channels
Used to control multiple conversations

Like how all of your TV channels travel across a cable

Divides up the 2.4GHz for each conversation

Selection of channels is usually automatic

Sometimes they use a single wide channel to get more bandwidth

Wireless Channels
going to a concert
Going to a Concert
  • General Admission compared to tickets for a seat
    • What’s the different experiences?
  • Wireless has a method to avoid collisions
  • A “ticketing” system
wireless detecting collisions
Wireless Detecting Collisions
  • Reserves a channel for conversation
    • No one else may use that channel
  • Request to Send (RTS) to the AP
  • If available, a Clear to Send (CTS) is sent
    • OK to send
    • Broadcast is sent to all, notifying channel in use
  • ACK sent to AP to notify done
    • All devices see ACK & know channel is open
activity setting the channel
Activity- Setting the Channel
    • Most of the time, automatic is fine
configuring the client
Configuring the Client
  • What is a wireless host known as?
    • STA (station)
  • It’s a device with wireless NIC & software for it
  • Settings MUST match AP
    • SSID, security settings, and channel
configuring the client software
As part of the OS

OR supplied with Wireless NIC

Contains link info, profiles, etc.

Usually the OS one is okay

Configuring the Client- Software
now test it
Look at signal strength

Then test data transmission

Use the ping test

Ping another PC 1st

If that doesn’t work, ping the AP

Now Test It…
lab 7 2 5 3 7 2 6 4
Lab &
  • Configure the AP and Wireless Client
  • Test
wireless security
Wireless Security
  • Tradeoff:
    • Ease & convenience of availability vs. putting info to the airwaves
  • What can they do?
    • Use your Internet for FREE
    • Access your computers
    • Damage files
    • Steal private info
  • Solution…SET UP SECURITY!
why is security important
Why is security important?
  • It’s possible that an individual or a business owner can be held responsible for what an unauthorized user does with your network
  • Computer Fraud Law
    • Accessing a computer without authorization
take security measures
Take Security Measures
  • Use all of the following to secure your wireless network:
    • Change the router password from the default
    • Change the SSID & disable the broadcast
    • Use MAC Address Filtering
    • Authentication (PSK)
    • Encryption (WPA)

Wireless Security

Change Router Password!


Wireless Security

Change SSID & Disable Broadcast!

change ssid disable broadcast
Change SSID & Disable Broadcast
  • Problem
    • SSID must be known to connect
    • Broadcast by default
  • Solution
    • Change the default settings
      • SSID
      • Passwords
      • IP addresses
    • These solutions help, but you can still be hacked!

Wireless Security

MAC Address Filtering!

mac address filtering
MAC Address Filtering
  • Use your device’s MAC address to limit connectivity to you KNOWN devices
  • You pre-configure the MACs in the AP
  • The AP will check its list
  • Only those in list will connect
mac address filtering1
MAC Address Filtering
  • What could go wrong?
    • Typo on the MAC address
    • New devices can’t enter network without adding Mac to the AP configuration
    • MAC address cloning
      • Sniff network traffic (MAC address in packet)
      • Find MAC addresses on that network
      • Change your MAC address to match one on the target network.

Wireless Security

Authenticate & Encrypt!

authentication to the ap
Authentication to the AP
  • Permitting entry to network
    • Like username & password
    • Works with encryption methods
  • Occurs before client connects to WLAN
  • 3 types:
    • Open (Default)
    • PSK (Used at home)
    • EAP (Used at big businesses)
open authentication
Open Authentication
  • Default
  • Anyone can connect
pre shared keys psk authentication
Pre-Shared Keys (PSK) Authentication
  • AKA “Personal”
  • Same passphrase set on AP & Client
  • Client asks AP to connect
    • One way
pre shared keys psk authentication1
Pre-Shared Keys (PSK) Authentication
  • AKA “Personal”
  • Same passphrase (or key) set on AP & Client
  • Client asks AP to connect
    • One way
eap authentication enterprise
EAP Authentication (Enterprise)
  • Two-way PLUS username/password
  • Talks to RADIUS server
    • Has database of allowed clients
    • In medium to large businesses
authentication mac filter
Authentication & MAC Filter
  • Authenticate 1st
  • MAC Filtering 2nd
  • These hacker from gaining access only!
  • Protect data traveling through the air
  • Prevents signal from being intercepted
    • “Sniffing”
  • WEP
  • WPA Personal (WPA-PSK; WPA Personal)
  • WPA2 Personal (WPA2-PSK; WPA2 Personal)
  • Wired Equivalency Protocol
    • All devices use same WEP key
    • 64 or 128 bits long
    • Set up using a passphrase
      • Generates Key 1 to use
    • WEAK!!!! Same static key
wpa or wpa2
  • Wi-Fi Protected Access
    • 64 to 256 bits long
    • New key each time client connects to AP
    • Pick how it encrypts
      • TKIP (Temporal Key Integrity Protocol)
      • AES (Advanced Encryption System)
  • WEP/WPA _______________ the data.
    • Encrypt
  • PSK/EAP are used to _____________ the user to the WLAN.
    • Authenticate
  • WEP or WPA. Which is stronger?
    • WPA
  • What’s the difference between open authentication & PSK?
    • PSK has the secret key

Configure encryption and authentication

access restrictions
You can control the type of data

Entering or leaving the AP

Going to/from a specific MAC or IP

Block by port #


Access Restrictions
  • Configuring Wireless Security
planning the wlan
Planning the WLAN
  • Determining the type of wireless standard to use
  • Determining the most efficient layout of devices
  • An installation and security plan
  • A strategy for backing up and updating the firmware of the wireless devices.
wireless standard
Wireless Standard
  • Bandwidth requirements, coverage areas, existing implementations, and cost.
    • This information is gathered by determining end-user requirements.
  • Ask the following…
    • What throughput is actually required by the applications running on the network?
    • How many users will access the WLAN?
    • What is the necessary coverage area?
    • What is the existing network structure?
    • What is the budget?
planning the wlan1
Planning the WLAN
  • Which 802.11 standards support a larger BSS?
    • Means less equipment to buy
  • Is there an existing standard in use?
  • Total Cost of Ownership (TCO) which includes the purchase of the equipment as well as installation and support costs
installation of devices
Installation of Devices
  • Site Survey
    • Measurements
    • Consider interference sources & locations
back it up 7 4 3 2 activity
Back It Up!!! Activity
  • Home & Small Business
    • Select Backup Configuration in Menu
    • To restore, select it
    • Factory Default Setting
updating the firmware
Updating the Firmware
  • The OS of the device is in firmware
    • Update for new features, etc
  • Get the current version
  • Research issues & features that may cause you to want the upgrade
  • Download it to a HD (directly connected machine)
  • Select Firmware upgrade
7 4 4 2 activity Activity
  • Upgrade the firmware
fundamentals of networking1

Fundamentals of Networking

Discovery 1, Chapter 7