Wireless networks overview

• Wireless network = Wi-Fi
• Type of Wireless Local Area Network (WLAN)
• Standardized by IEEE 802.11
• Allows devices in range of an access point to access the network.

Wireless terms

• Access Point
  • Access Point (AP) or Wireless Access Point (WAP)
  • Hardware device that allows wireless connectivity to the end devices.
• SSID (Service Set Identifier)
  • Unique name for a wireless Access Point
  • Inserted into the header of every data packet.
• BSSID (Basic Service Set Identifier)
  • MAC address of an access point
• GSM
  • Global System for Mobile Communication
• Bandwidth
  • Amount of information that may be broadcasted over a connection
• Hotspot
  • Places where wireless network is available for public use
• Orthogonal Frequency Division Multiplexing
  • Encoding method of digital data on multiple carrier frequencies
• Frequency-hopping spread spectrum (FHSS)
  • Method of transmitting radio signals rapidly switching a carrier among many frequency channels
• Phase Shift Keying (PSK)
  • Modulation technique where phase of carrier signal changed by varying the sine and cosine inputs.
  • Widely used for WLANs, biometric and contactless operations, along with RFID and Bluetooth communications.

Antenna patterns

• 
• 📝 Directional antenna patterns
  • Directional antenna
    • Also known as unidirectional antenna
    • Broadcasts and obtains radio waves from a single direction (can be e.g. 30 - 60 degrees)
    • E.g. Yagi (also known as Yagi–Uda antenna)
    • Most concentrated, higher range
    • Parabolic grid antenna
      • Based on the idea of a satellite dish
      • Can be attacked from farther away as it picks up Wi-Fi signal from 16 km and more
  • Bi-directional antenna
  • Omni-directional antenna
    • Broadcasts in 360 degrees
    • Most common type of antenna used in wireless communications and networks, especially WiFi
    • Used also in wireless base stations
    • Least concentrated and lower range
    • 
    • Dipole: Used for closer proximity e.g. mobile phones, client connections instead of site-to-site

Wireless encryption

Wireless encryption comparisons

WEP

• Wired Equivalent Privacy
• 1997, to provide data confidentiality
• Stream cipher RC4 for confidentiality
• CRC-32 checksum for integrity
• Authentication using WEP-Open and WEP-Shared (using a shared key) modes
• ❗ Weak as it reuses small IVs which allows decoding of its shared key.

WPA

• Wi-Fi Protected Access
• 2003, replace WEPs weak encryption
• Uses Temporal Key Integrity Protocol (TKIP)
  • Major improvement over WEP
  • Dynamically changes key as system is used
  • Combined with larger IV, this defeats well known attacks
  • Uses RC4 encryption
• Authentication using WPA-PSK and WPA-Enterprise modes
  • WPA-PSK uses pre-shared (symmetric) key to encrypt the wireless data
• Improved payload integrity vs. WEP
  • Uses more secure message integrity check (MIC) known as Michael
  • Includes a frame counter to prevent replay attacks
• Still subject to attack

WPA2

• Also known as Wi-Fi Protected Access 2 or 802.11i
• 2004, replace WPAs weak cipher
• Authentication WPA2-Personal and WPA2-Enterprise modes
• Uses Advanced Encryption Standard algorithm (AES)
  • Much harder to decrypt than WPA or WEP
• 📝 Replaces TKIP with CCMP (AES-CCMP)
  • Also known as Counter Mode Cipher Block Chaining Message Authentication Code Protocol (Counter Mode CBC-MAC Protocol) or CCM mode Protocol (CCMP)
  • Uses AES as encryption algorithm instead of RC4 in WPA.

WPA3

• Wi-Fi Protected Access 3
• 2018, introduce Dragonfly handshake, protects against dictionary attacks
• Authentication using WPA3-Personal and WPA3-Enterprise

Wireless cryptographic differences

	WEP	WPA	WPA2	WPA3
Encryption	RC4	RC4 + TKIP	AES-CCMP	AES-CCMP & AES-GCMP
IV Size (Bits)	24	48	48	48
Key Length (Bits)	40/140	128	128	128/256
Integrity Check	CRC-32	Michael/CRC-32	CBC-MAC, CCMP	BIP-GMAC-256

WPA2 and WPA3 Operation Modes

Personal

• Intended for home use, easier setup

Enterprise

• More complex setup, more granular control
• Uses RADIUS authentication with Extensible Authentication Protocol (EAP) extensions for more security

WPA2 vs WPA3 operation modes

	Personal	Enterprise
WPA2	Also called WPA-PSK (pre-shared key) as it uses PSK to protect network access	Same encryption
WPA3	Also called WPA3-SAE (Simultaneous Authentication of Equals). Uses 128-bit key and Forward Secrecy against dictionary attacks.	Uses 192-bit key

Wireless standards

• 802.15.1 - Bluetooth

  • Read more on bluetooth

• 802.15.4 - Zigbee

  • Low-power, low-data-rate, and close-proximity wireless ad hoc networks.
  • Popular IoT connection protocol

• 802.16 - WiMAX

  • Wireless on "steroids"
  • Written for global development of broadband wireless metropolitan area networks.
  • Big range and fast.

• Comparing wireless standards

• 802.11 Specifications

  Standard	Distance	Speed
  WiFi	Medium (20-250 m)	Started slow (2 Mbit/s) but fast now (1300 Mbit/s)
  ZigBee	Smallest (1-100 m)	Slow (up to 0.25 Mbit/s)
  WiMax	Biggest (1.6 - 9.6 km)	Fast (up to 1 Gbit/s)

• 📝 Summary of the standards

  Standard	Year	Summary
  802.11 (WLAN/Wi-Fi)	1997	• 2.4 GHz • DSS, FHSS • Up to 2 Mbit/s • 20 - 100 meters
  802.11a (Wi-Fi 2)	1999	• 5 - 3.7 GHz • OFDM • Up to 54 Mbit/s • 35 - 100 meters
  802.11b	1999	• 5.4 GHz • DSSS • Up to 11 Mbit/s • 35 - 140 meters
  802.11c	2001	Bridge operation procedures; included in the IEEE 802.1D standard
  802.11d	2001	International (country-to-country) roaming extensions
  802.11e	2005	Enhancements: QoS, including packet bursting
  802.11f	2003	Inter-Access Point Protocol, Withdrawn February 2006
  802.11g (Wi-Fi 3)	2003	• 2.4 GHz • OFDM • Up to 54 Mbit/s • 38 - 140 meters
  802.11i	2004	Defines WPA/WPA2 encryption standards
  802.11n (Wi-Fi 4)	2009	• 2.4 - 5 GHz • MIMO-OFDM • Up to 600 Mbit/s • 70 - 250 meters
  802.11ac (Wi-Fi 5)	2012	• 5 GHz • MU-MIMO, • Up to 1300 Mbit/s • 70 - 250 meters
  802.11ax (Wi-Fi 6)	2019	• 1 - 6 GHz • MU-MIMO, OFDMA • Up to 11 Gbit/s • 70 - 250 meters
  802.15.1 (WPAN/Bluetooth)	2002	• 2.4 GHz • GFSK, π/4-DPSK, 8DPSK • Up to 50 Mbit/s • 70 - 250 meters
  802.15.4 (Low rate WPAN/ZigBee)	2003	• 0.868, 0.915, 2.4 GHz • O-QPSK, GFSK, BPSK • Up to 0.25 Mbit/s • 70 - 250 meters
  802.16 (WiMAX)	2005	• 2-11 GHz • SOFDMA • Up to 1 Gbit/s • 1.6 - 9.6 kilometers

• See also all 802.11 standards and amendments

Wi-Fi authentication

Wireless authentication modes

Open system authentication process (OSA)

• Uses WPA protocol.
• Complete free for all, no auth at all
• 

Shared key authentication process (SKA)

• Uses WEP protocol + a shared secret key
• 

IEEE 802.1x

• 📝 Authentication mechanism for both wireless and physical access to a network
• Authenticate devices to decide to give e.g. corporate or guest access
• Switches uses back-end authentication server, see AAA
• Can authenticate based on MAC address or other requirements (certificate, VLAN etc.)
• Per default all hosts on a wired connection (LAN) can see each other