Cheatography
https://cheatography.com
CompTIA Network+ certification course sum up. Oriented for cybersecurity later courses.
*This sheet is quite simplified as its goal is to prepare for cybersecurity certifications. Some purely tech topics are missing.*
Wireless Network
WIFI standard |
IEEE 802.11 |
| |
AdHoc (p2p) or Infrastructure mode (star topo) |
WAP |
Wireless Access Point |
| |
extend wired LAN into wireless domain, devices are in the same subnet, single collision domain. |
Wireless Router |
gateway device, routing capacity added. |
Wireless Service Sets
IBSS |
adHoc mod only, no AP, no internet |
BSS |
one single AP connected to network |
ESS |
Several AP to extend coverage |
Mesh Topology |
combination of several types (WIFI, MW, cellular, etc) |
AP Placement |
Enough coverage but limit ovelapping |
2.4GHz |
10-15% overlapping, but with diff. channels. Channels shall not overlap |
5 GHz |
2 cells separation minimum |
Sites survey |
heatmaps to dertemine coverage gaps |
Range extender |
wireless repeater |
Antennas
Effectiveness factors |
distance, pattern, environment |
Omnidirectional |
radiates equally in all directions |
Unidirectional |
focus power in one direction, covers long distances (Yagi antenna) |
802.11 standards
802.11b |
2.4GHz |
11Mbps |
802.11g |
" |
56Mbps |
802.11a |
5GHz |
56Mbps |
802.11ac (WIFI5) |
" |
3Gbps (MU-MIMO) |
802.11n (Wifi 4) |
2.4 and 5GHz |
150-600 Mbps (MIMO) |
802.11ax (Wifi 6) |
2.4, 5GHz & 6GHz |
9.6Gbps (MU-MIMO) |
|
|
Frequencies
DSSS |
Spread spectrum modulation, reliable, inefficent use of bandwith |
FHSS |
Spread spectrum modulation, increased security, limited bandwith, latency & complexity (syncro) |
OFDM |
Multi carrier modulation (52 streams) |
-------- |
-------------------------------- |
Channel |
virtual medium to exchange data |
2.4GHz |
11-14 channels (US, World, Japan) |
| |
1, 6 & 11 non-overlapping channels |
5GHz |
24 non-overlapping channels, 20MHz size |
Channel Bonding |
wider channel created with merging neighboring channels |
-------- |
-------------------------------- |
RFI |
Interferences due to similar fq on several devices |
CSMA/CA |
Collision avoidance principle |
| |
Request to Send <> Clear to Send |
Wireless Security
PSK |
Pre-Shared Key = WIFI Key |
WEP |
802.11 original security standard |
unsecure |
Initialization Vector (IV) |
WPA |
TKIP (IV+RC4) |
replace WEP |
MIC (integrity check) |
WPA2 |
802.11i standard |
strong |
CCMP integrity check |
| |
AES encryption |
Authentication |
Entreprise vs Personnal mode |
| |
credentials vs PSK |
802.1x |
network authentication for each user |
EAP |
secured tunneling using 802.1x |
MAC Filtering |
listing of permitted MAC adresses |
NAC |
permission on devices' characteristics like OS or antivirus version |
Captive Portals |
web page with credential login or certificate |
Geofencing |
GPS or RFID real-world boundaries |
Disable SSID broadcast |
but can be detected with sniffing tools |
Rogue AP |
Malicious AP setup to capture packets |
Wardriving |
reconnaissance looking for unsecured Wless NW |
War chalking |
symbols on a wall to notify AP charac. |
|
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