Educational question about wpa_supplicant, NetworkManager, and user privileges

[Colm]

I've been experimenting with networking CLI tools for learning purposes, and sometimes I end up (intentionally or otherwise) killing the wpa_supplicant process in the default network namespace. NetworkManager can't connect to anything (wired or wireless) when I do this. No biggie, though, I just run:

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# systemctl restart wpa_supplicant
# systemctl restart NetworkManager

And I'm back in business. But I was hoping someone could help me understand a few things?

1) Why does killing wpa_supplicant interfere with NetworkManager's ability to connect me to unsecured networks including regular ethernet? I would have assumed wpa_supplicant was only for secure networks i.e. WPA/WPA2, and I know it can be used for 802.1X but I guess it does more than that-- or it wouldn't totally break NetworkManager? My initial web search didn't reveal any helpful documentation on this.

2) After NetworkManager restarts and I get network connectivity back with the desktop applet, why are certain drop-down options grayed out like NetworkManager doesn't have privileges to execute them or something? Why exactly does this happen? (i.e., beyond "because you restarted the processes as root"-- Right, but isn't that how it happens at boot time anyway? Why does it do this when I restart manually, but not when they are initially started?)

(Specifically, "Disconnect," "Connect to Hidden Wi-Fi Network..." and "Create New Wi-Fi Network..." when I left click on the applet, and when I right click, also "Enable Networking," "Enable Wi-Fi," and "Edit Connections..." are grayed out)

3) Regarding #2, how can I re-enable networking but restore regular user privilege to NetworkManager to un-gray-out those options?


Thanks,
Colm
(Using Linux Mint 20.2 MATE, Kernel 5.4.0-109-generic but same results on other recent kernels. Various ethernet and wifi hardware.)

[deepakdeshp]

Did you see the man for wpa_supplicant. If you need details for any Linux topic please see it's man. Most probably there will be a man in place.
https://linux.die.net/man/8/wpa_supplicant

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 man man

for information on man.