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EAP and RADIUS have support for a great variety of features or different methods that can be encapsulated there-in to perform authentication (e.g. it is possible to use different protocols that authenticate the user using a username and password, or using client certificates, or even SIM cards), but it is still up to the supplicant, NAS and authentication server implementations to choose which ones they support or not (even different NASes have been seen to send MAC addresses in different format, e.g. TP-Link Archer C20 sends 01-23-45-67-89-AB, while TP-Link TD-W8968 sends 0123456789ab. TP-Link TL-WR740N, in the case of the NAS MAC address, sends 01-23-45-67-89-AB:SSID, where SSID is the configured wireless SSID).

FreeRADIUS configuration files

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FreeRADIUS configuration files are many. They are located in /etc/freeradius/3.0 on Debian systems. Apparently, many other environments use a slightly different location. Most of them contain plenty of comments explaining what the configuration does and advice and warnings, but some understanding of the protocols, or getting used to, is often necessary to understand them. Here are The FreeRADIUS technical guide (link in "Support / Knowledge places" section) describes them in more detail along with more useful information. Here is a brief look at some of the configuration files/folders:

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