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

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.