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

[Margaret Cullen <[e-mail]>]

> That is a tried and true RADIUS tradition.  "I know the RFCs say to do X, but I'll just do something else instead."

That tradition extends well beyond RADIUS, unfortunately.

> DTLS is a lot more difficult.  I blame some of that on OpenSSL weirdness.  Their DTLS implementation has best been described as "alpha" for a long time.

This is the reason for my concern with mandating that servers implement DTLS.  

I am mostly okay with mandating that servers implement TLS-PSK, because it is not a major addition and it makes for a more complete, more useful RADIS/TLS server. 

I think RADIUS/DTLS is an awful lot to expect, though — especially because I don’t see any evidence that RADIUS/DTLS will ever be widely implemented or used.  Do you?

Many protocols that run over TLS don’t have a DTLS equivalent defined, at all.  Is there some important advantage that RADIUS/DTLS offers that RADIUS/TLS does not?  Is that advantage sufficient to warrant mandating both in every server implementation?

>  There's good reason for that, of course.  But I think it's best to document the system we need, rather than the system we have.

I absolutely agree with this when it comes to documenting good protocol behavior, ways to avoid known issues, etc.  I don’t think it extends to mandating the implementation of an entirely separate protocol.

> The alternative is to never fix RADIUS, or to give bad implementations a free pass.

Is there a reason that you think a RADIUS/TLS-only server would be a bad implementation, and that it would  become a good implementation if it also implemented RADIUS/DTLS?

Margaret