Chapter 20: Wireless Networks Flashcards
IEEE 802.11
WiFi standard
Connecting NIC to a client
Through a PCIe port or external USB
WAP
Wireless Access Point
Act like a hub, but could also be routers/switches
PoE
Power over Ethernet
Must come from a PoE capable switch
PoE Standards
802.3af (PoE)
802.3at(PoE+)
802.3bt (PoE++)
PoE Injector
Pushes PoE up to 100m
CSMA/CA
Carrier Sense Multiple access/collision avoidance
client will listen to see if another client is broadcasting, then waits random time before retrying it’s own broadcast
Due to all the overhead of constant frames, can impede performance
RTS/CTS
Request to Send/Clear to Send
Protocol that asks permission, then acts once permission is received
RTS frame gets sent, CTS frame gets received
ACK
Acknowledgement Frame
Client waits for this after sending data before next packet is sent
BSS
Basic Service Set - the WAP for a particular area
EBSS
Extended Basic Service Set - Multiple WAPs
Repeaters/Extenders
Rebroadcast signals to cover dead zones
Long Range Fixed Wireless
Uses directional antennas, interconnects remote buildings, can reach up to miles
Also known as point-to-point connections
May use proprietary protocols, may need FCC approval, may have reserved channels
WMN
Wireless Mesh Networks - devices act like routers, forwarding traffic.
devices are not WAPS, but “nodes.” Can communicate to each other, even if one node happens to be outside of another node’s range, as long as they have a path through intermediary nodes
3 methods of wireless security (and the two A+ methods)
1) MAC Address Filtering
2) Authentication
3) Data encryption
1) Disable broadcast (hidden network)
2) Change your channel
SSID
Service Set Identifier (network name)
SSID practices
1) Always change the default
2) Each WAP needs to share SSID in a network
3) SSID is included in all packets
4) disabling SSID broadcast hides network
WAP Setup
1) Consider location/placement
2) Decrease radio power so signal only reaches desired limit (trial and error)
3) Disable guest access
4)MAC address filtering (WAP will store given MACs)
Depreciated security methods
WEP (Wired Equivalent Privacy)
WPA (Wi-Fi PRotected Access)
WEP uses encryption level, passphrase, and a default key
WPA uses Personal/Pre-shared Key (PSK) or Enterprise configuration
WPS
Wi-Fi Protected Setup
WPA2
Uses AES (Advanced Encryption Standard)
Also compatible with TKIP (Temporal Key Integrity Protocol)
TKIP is an older encryption method, typically used for backwards compatibility
WPA3
Upgrades some security and usability issues with WPA2
Spread-spectrum
Radio waves send data in small, discrete chunks (how Wi-Fi works)
Bands for IEEE 802.11
2.4GHz, 5GHz, 6Ghz
Channels
20 MHz each, can be bonded
2.5GHz Band
11 or 13 Channels, but many overlap
Only 1, 6, and 11 are discrete with no overlap
5GHz Band
25 channels, no overlap
Channels can be bonded into wide (40Mhz) and ultrawide (80MHz), but this opens up to interference
6GHz Band
Could bond 8 channels into “superwide” 160MHz
AFC
Automate Frequency Coordination
WAP sends details about itself (location, height, etc) to central database, gets told what channels it should use
802.11a
First standard to use 5GHz band, has good throughput.
Max 54Mbps with 150ft range, really gets more like 25Mbps
802.11b
Uses 2.4GHz band, first ubiquitous standard. 11Mbps lab, 4-6Mbps reality.
Max range 300 ft
802.11g
2.4GHz band, backwards compatible with b devices
Combines best of a and b
Speed of a (54MBps) with range of b (300 ft)
802.11n
“Wi-Fi 4”
Dual band, both 2.4 and 5 simultaneously
MIMO - Multiple in, multiple out for simultaneous connections (more than one antenna)
lab 600Mbps, reality 100+ mbps
WAPs use trasmit beamforming to optimize signal and reduce deadspots
802.11ac
“Wi-Fi 5”
5Ghz only, allows for dual banding but applies 802.11n for 2.4 GHz band
Maxes at 1+Gbps
802.11ax
“High Efficiency Wireless (HEW) or Wi-Fi 6/Wi-Fi 6e”
2.4 and 5, 6e adds 6GHz band
Interference
Impact on data transmission, caused by things like large electrical appliances or too many smaller devices on the same channel (baby monitors, etc)
Signal strength can be checked in Network and Sharing settings, look at adapter settings
Omnidirectional vs Directional Antenna
Omnidirectional uses a dipole antenne
Directional typically uses a dish-type antenna
PAN
Personal Area Network, typically bluetooth enabled
Bluetooth versions and speeds
1 - 1 Mbps
2 - 3 Mbps (uses EDR)
3 - 24 Mbps (uses 802.11 protocol)
4 - Focused on Qol improvements, less power consupmtion “Bluetooth Smart”
5 - increased throughput, decreased range
Bluetooth benefit
resistant to interference, rapidly changes channels in 2.4Ghz band
Classes of Bluetooth Devices
Class - Power - Range
1 - 100Mw - 100m
2 - 2.5Mw - 10m
3 - 1Mw - 1m
Configurating a WAP
Use a wireless analyzer to pick the “quietest” channel
Apply MAC filtering
RADIUS
Remote Authentication Dial-In User Service
Security measure for accessing wifi
Open standard, partially encrypted, uses UDP ports 1812 & 1813
TACACS+
Terminal Access Controller Access-Control System Plus
Cisco developed, but opened a version for public use, uses TCP port 49
AAA
Authentication, Authorization, Accounting
