There is currently an issue to move the RADIUS authentication plugin into the third party plugin database.
The main reason for this is that the authentication that RADIUS uses (mcrypt) is deprecated in php 7.0.
It is highly recommended that if you are using RADIUS that you consider moving to another authentication system.
Is anyone still using this authentication plugin?
We aren't using it, but that's interesting that support of it is depreceated beyond a certain newness of PHP.
Because Eduroam uses RADIUS for authentication (I only know this because we have it rolled out to some of our wifi hotspots, and it's really reliable - unless you have a Windows 10 laptop anyway).
I think its more about the current implementation being tied to some mcrypt functions, which may be replaceable, but the user-base of the radius auth plugin does not seem like its a good use of time to focus on this.
I think there is no doubt that RADIUS is an extremely commonly used protocol in networking hardware, but I don't think its a natural fit for authenticating something like Moodle (and my own anecdotal evidence seems to be that I don't think there are not many users of the Moodle plugin at all). I imagine many orgs might use radius for that sort of network equipment based auth, but often backed with ldap (which could be a nicer moodle fit) or even with a nicer more convenient web-based SSO solution which avoids the need to constantly reauthenticate.
(I might be proved wrong here too )