WLAN Flashcards
WLAN
Wireless Networking
Ad Hoc wireless
Devices communicate with each other
No need for centralized AP
Infrastructure wireless
Communicate through router or access point
WAP
Wireless Access Point
Expands wired LAN into wireless domain
Single collision domain
IBSS
Independent Basic Service Set
Ad Hoc wirless
BSS
Basic Service Set
Infrastructure wireless
One AP connected to internet
ESS
Extended Service Set
Infrastructure wireless
Multiple APs connected to internet
2.4Ghz overlap
Cannot overlap on same frequency
5.0Ghz overlap
Same channels should be separated by at least 2 cells instead of 1
Omnidirectional antenna
Radiates power equally in all directions
Unidirectional antenna
focusses power in one direction for greater distances
Yagi antenna
DSSS
Direct Sequence Spread Spectrum
Series of signals known as chips
High environmental interference
Uses entire frequency spectrum to transmit
FHSS
Frequency Hopping Spread Spectrum
Devices hop between predetermined frequencies
Increases security
Hops occur on predetermined timer
OFDM
Orthogonal Frequency Division Multiplexing
Slow modulation rate with simultaneous transmission over 52 data streams
Allows for higher data rates while resisting interference between streams
2.4GHz channels
1, 6, 11
802.11
2.4 1 or 2 Mbps DSSS or FHSS 20m in 100m out
802.11a
5 54Mbps OFDM 35m in 120m out
802.11b
2.4 11 Mbps DSSS 32m in 140m out
802.11g
2.4 54 Mbps OFDM or DSSS 70m in 250m out
802.11n
2.4 and 5 >300 Mbps OFDM 70m in 250m out
802.11ac
5 >3Gbps OFDM 70m in 250m out
RFI
Radio Frequency Interference
Caused by similar frequencies to WLAN
CSMA/CA
Carrier Sense Multiple Access/Collision Avoidance
Controls access to medium
Listens for transmission to determine if safe to transmit
-If channel is clear, transmit Request to Send (RTS)
-Waits for acknowledgement
-If RTS received, respond with Clear to Send (CTS)
-If not received, device starts random back off timer
Pre-shared key
AP and client use same encryption key
All clients must know the same password
WEP
Wire Equivalent Privacy Original 802.11 security standard Static 40 bit pre-shared key Upgraded to 64 and 128 bit keys 24-bit initialization vector sent in clear text Unsecure
WPA
WiFi Protected Access
Replaced WEP
Follows Temporal Key Integrity Protocol (TKIP)
48 bit initialization vector
Rivest Cypher 4 (RC4) used for encryption
Message Integrity Check (MIC) (hashing)
Users required to authenticate before exchanging temporary keys
WPA2
WiFI Protected Access 2
Cipher Clock Chaining Message Authentication Code Protocol (CCMP)
Advanced Encryption Standard (AES) - 128 bit key or above
Personal Mode - pre-shared keys
Enterprise Mode - Centralized authentication
If asked about Open
No security
If asked about WEP
IV
If asked about WPA
TKIP and RC4
If asked about WPA2
CCMP and AES
802.1x
Network Authentication
Users authentication with their own credentials
EAP
Extensible Authentication Protocol Authentication using 802.1x EAP-FAST (Flexible Authentication via Secure Tunneling) EAP-MD5 EAP-TLS
MAC Address filtering
Configures AP with list of permitted MAC addresses
NAC
Network Access Control
Permits or denies access to network based on characteristics of device
Does not use credentials
Captive Portal
Page that appears before user is able to access network resources
Accepts credentials and presents them to authentication server
Geofencing
GPS or RFID
Active or passive
Used to determine access/network authentication
Disable SSID Broadcast
Configures AP to not broadcast name of WLAN
Easy to find
Rogue Access Point
AP set up to lure users to connect
Can capture all packets through rogue AP
War driving
Looking for unsecure wireless networks
War chalking
Users write symbols on wall to notify others of AP characteristics
