Last Post: June 10:
can someone describe the corresponding wifi machine states when using a captive portal? For example, which state corresponds to the moment when the captive portal is displayed to the user?
Not being an expert on this particular subject, perhaps the best I can do is help point the way.
I had started an earlier response to you, but cut it short when I realized I didn't have a succinct answer. The only way I really understood was via DNS re-directs. Did you check Wikipedia ? It lists three different implementations. Notice that different methods have different weaknesses:
Here is a list, first reported by @@ron here on the forums listing several Portal products. The follow-on comments add to the original list. It was last updated in 2016:
If you are looking for something with an actual State Machine form of explanation, try this one:
I'm sure a product's sales department could provide you with more detail on their particular product. Just have a good idea of the various pitfalls before you make a final decision. If they hide too much behind their layer of "secret sauce", be leery.
Naturally the normal 802.1 authentication and association steps are still required for the client and AP to communicate at all.
Hope this helps.