A preset locally administered MAC address is used as the BSSID of the AP. Changing the MAC address of the Wifi interface doesn't affect this.
The Internet Sharing in System Preferences invokes configd,
which then communicates with wifid via IPC to change the mode of the Wifi interface.
Problem: Internet Sharing only works when Security is set to None in Wi-Fi Options. Version: macOS 10.12.4 Model: MacBook Air (13-inch, Mid 2011) Wi-Fi:
Software Versions:
CoreWLAN: 11.0 (1200.31)
CoreWLANKit: 12.0 (1200.31)
Menu Extra: 12.0 (1200.46)
System Information: 12.0 (1200.3)
IO80211 Family: 12.0 (1200.12.2)
Diagnostics: 7.0 (700.5)
AirPort Utility: 6.3.7 (637.6)
Interfaces:
en0:
Card Type: AirPort Extreme (0x14E4, 0xE9)
Firmware Version: Broadcom BCM43xx 1.0 (5.106.98.100.24)
MAC Address: <private>
Locale: RoW
Country Code: US
Supported PHY Modes: 802.11 a/b/g/n
Supported Channels: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 149, 153, 157, 161, 165
Wake On Wireless: Supported
AirDrop: Supported
Symptom:
[wifid] <en0> Client added <Interface : en0
STA :
MAC : <private>
Interface : en0
Cache Time : 0 secs
Last Update : 0 secs
SSID : <private>
Channel : 11 (20 MHz wide)
Security : Open
Maximum PHY Rate : 54 Mbps
isAssociated: NO
Last Deauth Reason: 1
Lifetime: 1459371779007
Joined: 0
Left: 0
isWOWSleep: NO
[wifid] <en0> Client Kicked: <MAC address> for reason <Unspecified reason>
Wait. Security : Open? Client side is configured to use WPA2 but not recognized?
Relevant log:
<kernel> en0: Terminating supplicant.
<kernel> RSNSupplicant: Releasing authenticator for <private>
<kernel> Got incomplete channel sequence length 0, should be 16