[lwip-users] captive-portal pop-up

[Notorious Tre W]

I've been trying to get captive portal to work using the ESP8266 but 
want it to trigger the helper pop-ups on at least android and iphone. I 
don't have an iphone to test at the moment, but have had no luck on the 
android.  I have the DNS pointing all queries to the softAP address and 
have the webserver code responding to the /generate_204 url. But 
although I can see the various google.com look-ups on DNS and the 
response going back with the local IP, I never see the request at the 
web server. (I'm assuming the device is not trusting the local net 
address and is falling back on some cached address).

I see a couple of different forum posts where people are reporting 
similar results and lack of ability to trigger the helper pop-up on both 
newer versions of android and iphone, so I'm assuming it's not just my 
own experience. Assuming the request is in fact going out but to an 
address other than the softAP address, is it possible with lwip to do 
something akin to a linux iptables rule and redirect any port 80 
requests to the softAP address? (mind you, I am not connecting my 
devices to the internet so the only content available is that on the 
device in question)

My application is going to be geared toward non-technical users assuming 
I can get it to work and in some cases may be seen by users that have 
had no contact with me what-so-ever. So being able to direct them to a 
page of content is essential to it working properly. I can ultimately 
try to create companion 'apps' for android and ios to handle the 
interaction and connect to the proper device address if absolutely 
necessary, but I would prefer to avoid that if possible or reserve it as 
an 'added' use feature of my application for users that are more 
interested in using them.

It's been a while since I've dabbled with tearing protocols apart and my 
C/C++ skills are rusty and thus beginner-esc (although I am familiar 
with other programming languages and constructs). Namely I'm just 
interested to know if it's possible to do what I want and how difficult 
it might be before I spend a lot of time learning the library [with what 
limited documentation there is available out there] and trying to figure 
out how to get it to do what I want [with what appears to be limited 
examples of anyone else doing something similar]. Of course, if anyone 
knows of any such examples, they would be greatly appreciated! I just 
don't want to spend a lot of time learning something if it might be 
easier just to learn more of the android/ios stuff to pursue the 
dedicated companion app solution instead.


SW