Re: [radext] TLS-PSK and RADIUS/(D)TLS - MTI trust models

[Alan DeKok <[e-mail]>]

On Aug 11, 2023, at 6:03 AM, Jan-Frederik Rieckers <[e-mail]> wrote:
> We have had discussion about the Requirement for TLS/DTLS on the client side an have reached a consensus, as far as I read the list, that the server should support both, but the clients can choose to implement only one.
> Would it be a good idea to continue this with the mutual authentication as well?
> 
> The idea would be: RADIUS/(D)TLS servers MUST implement certificates with PKIX trust model and TLS-PSK, RADIUS/(D)TLS clients MUST implement at least one of those two.

  I think that's reasonable.

> This way we still ensure complete compatibility, but RADIUS clients that currently only support RADIUS/UDP with shared secrets can upgrade to RADIUS/(D)TLS easily without the need to implement a whole PKIX certificate validation stack.
> 
> However, this is a significant change in the spec, since RFC 6614 did not mandate TLS-PSK.
> 
> Implementation status, as far as I know:
> 
> * FreeRADIUS implements TLS-PSK for RadSec
> * Radsecproxy just became capable in the current master, will probably be released in the 1.11 version.
> 
> I have not checked RADIATOR and I'm not sure if there are more RADIUS/TLS implementations out there.

  It's hard to say.  Publicly available documents don't list TLS-PSK for many implementations, so my guess is "no".

  Alan DeKok.