/me considers copying and pasting the answer from the dupe. :-p

@womble I still believe that the question as asked is within the criteria, and the "benefit of the doubt" reinterpretation is what leans towards the unacceptable question and have repeatedly stated that's not what I asked. I've already accepted this answer because of the peer pressure that's clearly resulted, and I now have an answer to my original question in the comments above. I can see that we're not going to agree on this, so let's just leave it at that, please.

@Anubioz Thanks. I really appreciate the effort. I keep a log of my google results and it appears that the results that appear now are different to when the question was raised, so thanks for pointing that out. :-)

@womble I'm sorry that you see it that way. I believe that some people think I was asking a different question than what is actually written, since the only explanation here appears to be rewriting my question so that it doesn't fit the criteria.

Re: The second dot point, I maintain I didn't ask the question that way because that was not what I was interested in. It was the apparent lack of information that was bizarre and I felt that was a valid question. In all reasonableness, I felt I has missed something and honestly expected an answer like "Yes, but Diameter, because it's doing something very clever, has chosen not to call them APIs, UIs or CLIs, but "Purple Fuzzy Unicorns" to emphasise that they're not working with a traditional security model. You'll need a PFU editor to interact with it this way."

I came back to respond to the first dot point, but I also see that @ryan-babchishin has pointed this out, too. Just because an answer is binary, that doesn't mean it evades an explanation. The first point is misleading because, as you point out, the system wouldn't let you answer that way, and I already knew that I wouldn't get just a "yes" or "no", but an explanation that would be helpful.

Ok, Thanks everyone for the clarification/validation. :-D As an aside, the technical problem I have is a generalised flexible security model which RADIUS doesn't offer, so I saw it as appropriate here, but I must be misunderstanding where that boundary is, too.

@EEAA, fair enough. Thanks. Now why can't that be an answer? At least that way I wouldn't have been made to feel stupid, alone, and misunderstood. "Some technologies (although marketed as successors or 'better' fail to gain traction for whatever reason. So there may not be the tool you describe. Maybe you can build it, but the people who use RADIUS appear not to see a significant need to migrate to this technology, resulting in a lack of tools."

@yoonix, no attempt to skirt the rules here. I just can't understand why there's so little information (or questions) on a supposedly-well-used 13-year-old protocol.