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