IEEE 802.11

• IEEE 802.11
  • Wi-Fi
• OFDMA
• BSS Coloring
• Beamforming
• WPA3
• WEP
• WDS
• AP - Access Point
• Station = AP
• Plug-n-Share
• IBBS - Ad Hoc
• 802.11k/v/r - WiFi 快速漫游协议

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• IEEE 802.11n - Wi-Fi 4
  • 150Mbps - 低端规格
  • 300Mbps - 目前常见
• AC - IEEE 802.11ac - Wi-Fi 5
  • AC2900 -> 2900Mbps
  • MIMO
• AX - IEEE 802.11ax - Wi-Fi 6
  • AX1800 -> 1800 Mbps
    • 2.4 GHz 574 Mbps + 5 GHz 1201 Mbps

	WiFi 4	WiFi 5	WiFi 6/6E	WiFi 7
Date	2007	2013	2019/2021	2024
IEEE	802.11n	802.11ac	802.11ax	802.11be
Date Rate	1.2Gbps	3.5Gbps	9.6Gbps	46Gbps
Bands	2.5,5GHz	5GHz	2.5,5GHz/6GHz	1-7.25GHz
Security	WPA2	WPA2	WPA3	WPA3
Channels	20,40MHz	20,40,80,80+80,160MHz	same as WiFi 5	<= 320MHz
Modulation	64 QAM, OFDM	256 QAM, OFDM	1024 QAM, OFDMA	4096 QAM, OFDMA
MIMO	4x4 MIMO	4x4 MIMO,DL MU-MIMO	8x8 UL/DL MU-MIMO	16x16 MU-MIMO

• WiFi 7 - 9.6 Gbpsx1.2x2x2=46 Gbps

traffic

IEEE	Data Rate
IEEE 802.11a	54 Mbps
IEEE 802.11b	11 Mbps
IEEE 802.11g	54 Mbps
IEEE 802.11n	450 Mbps
IEEE 802.11ac	1734 Mbps
1024QAM (2.4GHz)	750 Mbps
1024QAM (5GHz)	2167 Mbps

IEEE	for
802.11s	mesh networking
802.11r
802.11w

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• IEEE 802.11ax
  • 替代 IEEE 802.11ac
  • 用于高密度场景
  • OFDMA - Orthogonal frequency-division multiple access
  • Wi-Fi 6 - 2.4 GHz, 5 GHz
  • Wi-Fi 6E - 6 GHz

WiFi Roaming

• Scanning
• Authentication
• Re-association
• 常见 AP 自带功能 - 无线客户端的信号低于设定值主动断开连接

Mesh

• 硬件 - IEEE 802.11s
  • Linux IEEE 802.11s
  • 有线 Mesh
  • 无线 Mesh
    • 三频 - 预留一个频段用于 Mesh 回程
• 动态链路状态
  • B.A.T.M.A.N. - Better Approach To Mobile Adhoc Networking
    • https://www.open-mesh.org/
  • OLSR - Optimized Link State Routing
  • OSPF
• AC+AP - 最佳、需要预布线

Security

• airmon-ng - 抓包
• aircrack-ng - 爆破
• hashcat - 爆破 hash
• Crack WPA/WPA2 Wi-Fi Routers with Aircrack-Ng and Hashcat
  • HN
• WEP, WPA 不安全，很容易攻击
• WPA2 只能抓包爆破
• d33tah/call-for-wpa3
• derv82/wifite2

Tips

• Captive Portal

• Captive Portals - text/plain

  • HN Discussion

• IEEE 802.11 - Wikipedia

• Wifi BSS ESS SSID ESSID BSSID

• IEEE 802.11 frame format vs IEEE 802.3 frame format

  802.11na 非官方

  802.11n can run in either the 2.4 GHz or 5.8 GHz bands. 802.11a is 5.8GHz only. 802.11g is 2.4 GHz only.

Juniper uses the terms 80.211na to mean "5.8 GHz 802.11n" and 802.11ng to mean "2.4 GHz 802.11n."

• Understand Wi-Fi 4/5/6/6E/7 (802.11 n/ac/ax/be)

Wi-Fi 4 (2.4 GHz 802.11n) to Wi-Fi 5 (5 GHz 802.11ac), and now to Wi-Fi 6 (6 GHz 802.11ax 802.11ac wireless device will likely max out at around 600 Mbps (±60 Mbps) for 2x2 MIMO, to 1000 Mbps (±200 Mbps) for 4x4 MIMO

Gen Spec Year Speeds Unofficial name 802.11 1997 2 Mbps Wi-Fi 0 (beta) First 802.11b 1999 11 Mbps Wi-Fi 1 Second 802.11a 1999 54 Mbps Wi-Fi 2 Third 802.11g 2003 54 Mbps Wi-Fi 3