Chapter 6- Wireless Networking
IBSS
(Independent Basic Service Set)- uses an ad hoc topology. Small # of nodes closely positioned transmit directly to each other w/o an intervening connectivity device
MIMO
(Multiple Input Multiple Output) - multiple access point and client device antennas may issue signal to one or more receiver. MIMO increase range and throughput
MU-MIMO
(Multiuser MIMO) - newer tech that allows multiple antennas to service multiple clients simultaneously
RTS/CTS
(Request to send/clear to send) protocol ensures packets are not inhibited by other transmissions
SSID?
(service set identifier) the name of an access point.
WLANs work at OSI layer?
1 & 2 They support TCP/IP
Notable Wifi standards
1. 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax 2. 802.11n
Two techniques networks can use for combining multiple frames into one larger frame
1. A-MSDU (aggregated max service data unit) 2. A-MPDU (Aggregated Mac protocol data unit)
Additional security options
1. AP/ antenna placement 2. geofencing 3. guest network 4. wireless client isolation 5. captive portal 6. Iot Access consideration
Most wireless devices implement two techs:
1. FHSS (Frequency hopping spread spectrum) 2. DSSS ( Direct sequence spread spectrum)
List of capabilities common to wireless testing tools:
1. Identify transmitting access points, stations, and channels Measure signal strength from an AP 2. Indicate the effects of attenuation, signal loss, and noise 3. Interpret signal strength information 4. Ensure proper association and reassociation between APs 5. Capture and interpret traffic 6. Measure throughput and assess data transmission errors 7. Analyze characteristics of each channel
TKIP accomplished what improvments?
1. MSG integrity 2. key distribution 3. encryption
The most secure communication is made possible by combining what?
1. Radius server with WPA/WPA2 known as WPA-Enterprise/ WPA2-Enterprise
No wifi connection
1. Wrong SSID 2. Encyprtion protocol mismatch 3. Incorrect passphrase 4. static channel utilization 5. mismatch RF band 6. mistmatch standards 7. long AP association time
Ap variables set during installation?
1. admin password 2. SSID & if SSID is broadcast 3. Security 4. If DHCP is used or not
SSID contains?
1. beacon frame info 2. is configured in the AP config utility and is recommended that it be changed from default setting
What to consider when installing AP?
1. distance 2. type & number of obstacles 3. coverage 3. interference
Slow wifi connection
1. insufficient wireless coverage 2. RF attentuation/signal loss 3. interference 4. channel overlap 5. wireless standard specification 6. simultanous wire and wireless connection 7. problmes with firmware 8. incorrect antenna type 9. mismatch antenna polorization 10. client saturation or overcapcity 11. client disassociation
3 frame types that 802.11 specifies a max sublayer frame?
1. management frame- association/reassociation 2. Control- medium acess & data delivery 3. data - carry data sent between stations
What happens when obstacles are in a signals way?
1. pass through the object 2. be absorbed by the object
IR sensors collect info on:
1. presence/level of fluid 2. bloodflow 3.proximity to device 4. commands from control device
MU-MIMO characteristics
1. reduces congestion & contributes to faster data transmission 2. is avaibale with WAVE 2 802.11ac products
Z wave two basic functions?
1. signaling to manage wireless connections 2. control to transmit data/ commands between devices
Wifi, bluetooth, and zigbee use ? (FHSS OR DSSS)
1. wifi-DSSS 2. Bluetooth- FHSS 3. ZigBee- DSSS
TKIP
802.11i encryption key generation & management scheme to improve security for legacy WEP-based devices
Wireless spectrum spans frequency ranges or bands between?
9 KHz & 300 GHz
z wave
A smart home protocol
encryption uses what?
AES (adv. encryption standard) better encryption
BSS identifier?
BSSID ( basic service identifier)
What ensures data confidentiality with both encryptions and packet authentication
CCMP (counter mode) with CBC (cipher block chaining) MAc protocol
802.11 standard specify the use of what procedures to access a shared medium?
CSMA/CA (Carrier sense multiple access with collision)
radius server is used in cooperation with an authentication mechanism called
EAP
Interference
EM waves interfere with wireless communication.
ESS identifier?`
ESSID
How do antennas and electrical signals work?
Electrical signals travels from the transmitter to an antenna, which then emits the signal as a series of electromagnetic waves into the atmosphere. At the destination, another antenna accepts the signal and a receiver converts it back to current.
Wireless spectrum
Electromagnetic frequencies used for data/voice communication
Range
Geographical area that an antenna can reach
Examples of IoT devices that are part of a home?
Health monitor, smart speaker, smart thermostat, smart cameras
RFID used commonly for?
Inventory
What is ZigBee used for?
IoT devices such as fleet management, building automation, HVAC control
Omnidirectional antenna
Issues and receives wireless signals with equal strength and clarity in all directions.
Directional (unidirectional ) antenna
Issues wireless signals along a single direction.
LOS
Line of sight- when signal travels in a straight line directly from transmitter to receiver
NFC
Near field communication- Transfer data over short distance
OFDMA
Orthogonal Frequency Division Multiple Access- supports more efficient multiuser functionality for 802.11 ax devices
Signal- to -noise ratio
Portion of noise to the strength of signal noise/stregth= Signal-to-noise ration
RFID?
Radio Frequency Identification- electromagnetic fields to store data
RADIUS
Remote Authentication Dial-in User service an open source authentication and authorization service
Fixed frequency?
Single frequency for that band
WPA
Wifi protected access- dynamically assigns every transmission its own key
Multipath
Wireless signals follow different paths to destination
remote wipe
admin having a feature to allow off boarding remotely
z wave is also called a what? and what are some examples of it?
also called a hub and smart lighting, smart sensors, smart plugs etc
ANT+
an ad-hoc wireless protocol operating at 2.4 GHz
passive scanning
ap take initiative. wireless devices listen for a beacon frame
Site survey?
asses client requirement, facility characteristics, coverage area
BSS
basic service set- USES AN INFRASTRUCTURE TOPOLOGY. group of stations share an access point
Frame aggreation
combines multiple frames into one larger frame
RTS/CTS decreases what?
decreases network efficiency but can be efficient for large transmission packet
Spectrum analyzer
device that can access quality of wireless signal
ESS
extended service set. uses mesh topology. several access points are connected to same LAN network
EAP
extensible authentication protocol- framework for authentication clients and servers
How does an NFC tag collect power?
from phones or other device by magnetic induction
war chalking
hacker draw symbols near vulnerable ap
War driving
hacker searches for unprotected wireless network by driving around with a laptop configured to receive & caputre wireless data transmission
examples of ANT+
heart rate monitors, gps, smartwatch, bicycle computer, fitness equipment
Bluetooth does what to reduce interfence?
hops between frequencies within that band
Whats a wireless range extender?
how a wireless signal can be amplified by increasing the power of the transmission or extended by repeating the signal
WPS attack
involved cracking a PIN in order to access AP setting
On- boarding
involved installing a specific program/app onto a device to give trusted access to certain portions of netwrok
WPA attck
involves interception of the network keys communicated between stations and APs also called WPA cracking
is IR visible?
just below the spectrum visible to eye
Wired/wireless signals share which layer?
layer 3 and up
ZigBee
low power wireless technology. Holds small amounts of data
Off-boarding
opposite of on boarding
Msg integrity ensures what?
packet is coming from declared source
Mac filtering
prevents ap from authenticating any device whose MAc addy isnt listed
Association
process where packets are exchanged between computer and an access point in order to gain internet access
evil twin
rogue AP planted in a network geographical area to pose as an authorize ap
encryption algorithms
scramble data into a format that cannot easily be interpreted if the signal is intercepted
Fading
signal runs into obstacles, energy is gradually faded
wireless analyzer (wifi analyzer)
software that can 1. evaluate wifi network availability 2. optimize wifi signal setting 3. help identify wifi security threats
Ap devices combine what at home?
switching, routing, and other network function
Antennas radiation pattern describe what?
the relative strength over a 3 dimensional area of all electromagnetic energy that antenna sends/ receives
Active scanning
the wireless client takes the initiative by transmitting a special frame known as a probe
Channel bonding
two adjacent 20-MHz channels can be bonded to make 40-MHz channel
802.11 standard uses ack packets to what?
verify every transmission & requires more overhead than 802.3
How do WLAN transmit signals?
via RF waves
reflection
wave encounters obstacles and bounces back
Refraction
wave travels through objects the wave direction, speed, and wavelength are altered (refracted)
Propagation
way in which a wave travels from one point to another
Scanning
when a wireless devices surveys its surrounding for an access point
scattering`
wireless signal encounters object and signal is diffused or scattered in multiple directions
Diffraction
wireless signal is split into secondary waves when it encounters an obstruction