14.1 Wireless Concepts

Wireless Terminologies

  • GSM: Universal system used for mobile transportation for wireless network worldwide.
  • Bandwidth: Describes the amount of information that may be broadcasted over a connection
  • BSSID: The MAC address of an access point that has set up a Basic Service Set (BSS).
  • ISM band: A set of frequency for the international Industrial, Scientific, and Medical communities.
  • Access Point: Used to connect wireless devices to a wireless network.
  • Hotspot: Places where wireless network is available for public use.
  • Association: The process of connecting a wireless device to an access point.
  • Orthogonal Frequency-division Multiplexing (OFDM): Method of encoding digital data on multiple carrier frequencies.
  • Direct-sequence Spread Spectrum (DSSS): Original data signal is multiplied with a pseudo random noise spreading code.
  • Frequency-hopping Spread Spectrum (FHSS): Method of transmitting radio signals by rapidly switching a carrier among many frequency channels.

Wireless Network

  • Wi-Fi refers to wireless local area networks (WLAN) based on IEEE 802.11 standard.
  • It is a widely used technology for wireless communication across a radio channel.
  • Devices such as a personal computer, video-game console, smartphone, etc. use Wi-Fi to connect to a network resource such as the Internet via a wireless network access point.
  • Advantages:
    • Installation is fast and easy and eliminates wiring through walls and ceilings.
    • It is easier to provide connectivity in areas where it is difficult to lay cable.
    • Access to the network can be from anywhere within range of an access point.
    • Public places like airports, libraries, schools or even coffee shops offer you constant Internet connections using Wireless LAN.
  • Disadvantages:
    • Security is a big issue and may not meet expectations.
    • As the number of computers on the network increases, the bandwidth suffers.
    • Wi-Fi enhancements can require new wireless cards and/or access points.
    • Some electronic equipment can interfere with the Wi-Fi networks.

Wi-Fi Networks at Home and Public Places

  • Wi-Fi at Home: Wi-Fi networks at home allow you to be wherever you want with your laptop, iPad, or handheld device, and not have to make holes for or hide Ethernet cables.
  • Wi-Fi at Public Places: You can find free/paid Wi-Fi access available in coffee shops, shopping malls, bookstores, offices, airport terminals, schools, hotels, and other public places.

Wireless Technology Statistics

  • Why Wireless Technology Matters?
    • More than half of all open Wi-Fi networks are susceptible to abuse.
    • There will be more than 7 billion new Wi-Fi enabled devices in the next 3 years.
    • 71% of all mobile communications flows over Wi-Fi.
    • By 2017, 60% of carrier network traffic will be offloaded to Wi-Fi.
    • A Wi-Fi attack on an open network can take less than 2 seconds.
    • 90% of all smartphones are equipped with Wi-Fi capabilities.

Types of Wireless Networks

Wireless Standards

Amendments Freq. (GHZ) Modulation Speed (Mbps) Range (ft)
802.11a 5 OFDM 54 25-75
802.11b 2.4 DSSS 11 150-150
802.11g 2.4 OFDM, DSSS 54 150-150
802.11i Defines WPA2-Enterprise/WPA2-Personal for Wi-Fi " " "
802.11n 2.4, 5 OFDM 54 ~100
802.16 (WiMAX) 10-66 70-1000 30 miles
Bluetooth 1:8 1-3 25

Service Set Identifier (SSID)

  • SSID is a token to identify a 802.11 (Wi-Fi) network; by default it is the part of the frame header sent over a wireless local area network (WLAN).
  • It acts as a single shared identifier between the access points and clients.
  • Access points contunuously broadcasts SSID, if enabled, for the client machines to identify the presence of wireless network.
  • SSID is a human-readable text string with a maximum length of 32 bytes.
  • If SSID of the network is changed, reconfiguration of the SSID on every host is required, as every user of the network configures the SSID into their system.
  • A non-secure access mode allows clients to connect to the access point using the configured SSID, a blank SSID, or an SSID configured as "any".
  • Security concerns arise when the default values are not changed, as these units can be compromised.
  • The SSID remains secret only on the closed networks with no activity, that is inconvenient to the legitimate users.

Wi-Fi Authentication Modes

Wi-Fi Authentication Process Using a Centralized Authentication Server

Wi-Fi Chalking

  • WarWalking: Attackers walk around with Wi-Fi enabled laptops to detect open wireless networks.
  • WarChalking: A method used to draw symbols in public places to advertise open Wi-Fi networks.
  • WarFlying: In this technique, attackers use drones to detect open wireless networks.
  • WarDriving: Attackers drive around with Wi-Fi enabled laptops to detect open wireless networks.

Wi-Fi Chalking Symbols

Types of Wireless Antennas

  • Directional Antenna: Used to broadcast and obtain radio waves from a single direction.
  • Omnidirectional Antenna: It provides a 360 degree horizontal radiation pattern. It is used in wireless base stations.
  • Parabolic Grid Antenna: It is based on the principle of a satellite dish but it does not have a solid backing. They can pick up Wi-Fi signals ten miles or more.
  • Yagi Antenna: Yagi is a unidirectional antenna commonly used in communications for a frequency band of 10 MHz to VHF and UHF.
  • Dipole Antenna: Bidirectional antenna, used to support client connections rather than site-to-site applications.

Parabolic Grid Antenna

  • Parabolic grid antennas enable attackers to get better signal quality resulting in more data to eavesdrop on, more bandwidth to abuse and higher power output that is essential in Layer 1 DoS and man-in-the-middle attacks.
  • Grid parabolic antennas can pick up Wi-Fi signals from a distance of ten miles.

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