Wireless Network

Aka: Wireless Network, Bluetooth Communication, Wi-Fi Communication

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II. Definitions

  1. Radio Frequency (RF) Communication
    1. Transmission and reception of wireless electromagnetic signals (at specific frequencies) for data communication
    2. Requires antenna, either internal (e.g. mobile device) or external (e.g. Wi-Fi router)

III. Background: Short-Range Wireless Standards (Personal Area Network or PAN)

  1. Radio-frequency identification (RFID, one-way communication)
    1. Active tags are self-powered (e.g. battery) and may be detected <100 meters away
    2. Passive tags must be relatively close to RFID reader to be detected
    3. https://en.wikipedia.org/wiki/Radio-frequency_identification
  2. Near Field Communication (NFC, two-way communication)
    1. Inter-device (e.g. phone) communication for data transmission (within 4 cm)
    2. Payments via Apple Pay, Android Pay to Visa PayWave, MasterCard PayPass
      1. Typically requires fingerprint, 2-factor authentication
    3. https://en.wikipedia.org/wiki/Near_field_communication
  3. Infrared
    1. Older, typically line-of-sight, 1-to-1 interface between devices (e.g. mobile, TV remote)
    2. https://en.wikipedia.org/wiki/Consumer_IR
  4. IEEE 802.15 Wireless Personal Area Network
    1. https://en.wikipedia.org/wiki/IEEE_802.15
    2. Bluetooth
      1. Personal area network typically within 10 meters (but up to 100 meters) at speeds up to 24 Mbits/s
      2. Only basic security protection, and can be hacked
      3. https://en.wikipedia.org/wiki/Bluetooth

IV. Background: Medium-Range Wireless Standards (Wireless Local Area Network or WLAN, 802.11)

  1. Approach
    1. Businesses typically use multiple access points, given relatively short Wi-Fi transmission distances
    2. Most Wi-Fi routers will accept connections from multiple different standards (e.g. B, G, N)
    3. Each frequency band has channels
      1. 2.4 Ghz band (B, G): 14 overlapping channels each with 5 Mhz spread (per FCC guidelines in U.S.)
        1. Non-overlapping channels (1, 6, 11, 14) have less chance of interferance from other signals
      2. 5 Ghz band (N, AC): 23 non-overlapping channels (per FCC guidelines in U.S.)
  2. Standards
    1. Old, rare, incompatible with other Wi-Fi standards
      1. 802.11a (5 Ghz): 54 Mbps (35 m or 115 ft distance)
    2. Older standards (2.4 Ghz has interference with microwaves and other devices in the same spectrum)
      1. 802.11b (2.4 Ghz): 11 Mbps (35 m or 115 ft distance)
      2. 802.11g (2.4 Ghz): 54 Mbps (38 m or 125 ft distance)
    3. Newer standards (higher frequency)
      1. 802.11n (2.4 or 5 Ghz): 65-150 Mbps (70 m or 230 ft distance)
      2. 802.11ac (5 Ghz): 86-780 Mbps (35 m or 115 ft distance)
  3. Encryption Protocols
    1. Precautions
      1. Use WPA2 connections (with a strong password)
        1. Do not use WEP or WPA (encryption broken in seconds to minutes)
    2. Wired Equivalent Privacy (WEP)
      1. Replaced with WPA (specifically WPA2)
      2. RC4 encryption that uses 64-128 bit key for entire data stream
      3. Has vulnerability that renders it insecure (do not use)
      4. https://en.wikipedia.org/wiki/Wired_Equivalent_Privacy
    3. Wi-Fi Protected Access (WPA)
      1. TKIP (temporal key integrity protocol) encryption that uses new 128-bit key for each packet
      2. Also allows for WiFi Protected Setup (WPS) - see below
      3. https://en.wikipedia.org/wiki/Wi-Fi_Protected_Access
    4. Wi-Fi Protected Access 2 (WPA 2, preferred)
      1. AES (advanced encryption standard) encryption that uses 192 to 256-bit keys (more data over wire)
      2. Personal version makes use of pre-shared key (PSK) - single password is encryption key (for all users)
      3. Enterprise versions use much more secure protocols (EAP, RADIUS)
        1. Can be coordinated with system login (e.g. active directory)
        2. Can automatically connect to WiFi for authenticated users without the user knowing password/key
    5. WiFi Protected Setup (WPS)
      1. Press WPS button on wireless router AND the button on the client device to create link
      2. Generates random pin that allows the device to access the router, but vulnerable
        1. Pins are typically short (8 digit) and can easily be brute-force hacked by software (e.g. Reaver)
        2. May be sufficient for home use, but avoid in business/enterprise
  4. Utilities: Wifi Analyzers
    1. See Computer Network for general network tools
    2. Acrylic WiFi
      1. Displays wireless signals, channels, standards, encryption and signal strength (RSSI - signal strength)
      2. Allows for selecting Wi-Fi channels that are not used by other potentially interfering Wi-Fi Routers
      3. https://www.acrylicwifi.com/en/wlan-software/wlan-scanner-acrylic-wifi-free/
    3. Ekahau Heat Mapper
      1. Displays Wi-Fi coverage maps to ensure consistent Wi-Fi coverage
      2. http://www.ekahau.com/wifidesign/ekahau-heatmapper
    4. inSSIder
      1. Displays information on Wi-Fi signals (helps to select channels with least interference)
      2. http://www.metageek.com/products/inssider/personal/
    5. Wi-Fi Pineapple
      1. Devices (e.g. Mark V) used for ethical hacking (white hat) to penetration test wireless access

V. Background: Long-Range Wireless Standards

  1. Various cell phone and other long-range data sources (e.g. WiMax, LTE, 3G/4G, CDMA)
  2. http://en.wikipedia.org/wiki/Comparison_of_wireless_data_standards

VI. References

  1. Warner (2016) CompTia A+ Networking, Pluralsight, accessed 1/14/2017

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