Handle Wifi Captive Portals

[ignoramous]

How do we handle restrictive networks like captive portals? Nebulo has a "pause when Captive Portal is detected".

Intranet DNS can be handled through DNS proxy setting #45

[Ch4t4r]

Nebulo does it by regularily doing a connectivitycheck (for example by checking whether http://connectivitycheck.gstatic.com/generate_204 returns 204 or something else). If a captive portal is detected (which would return 4xx or 200) it sends DNS queries to the networks DNS server unencrypted.

https://git.frostnerd.com/AndroidUtils/dnstunnelproxy/-/blob/master/library/src/main/java/com/frostnerd/dnstunnelproxy/CaptivePortalDnsHandle.kt

[ignoramous]

That's great defence in depth! No wonder Nebulo is as smooth as it is.

Android 11 has this: Captive Portal for Access points but won't be of use for app developers in its current form.

[yoshimo]

Apart from domains by Mozilla, Microsoft Apple, Amazon & Google to test for Captive Portals there is also https://datatracker.ietf.org/doc/html/rfc8952 to find these.
I think the first and only requests when joining a WiFi network should be a captive portal test. Everything else should be held back until we know there is no pending captive portal "login".

The next step could be recording login scripts for certain captive portals. Sometimes it is a fixed password&username that works across the entire network of the provider, sometimes it is a simple password like "password" or the name of the WiFi itself.
Sometimes you just need to mark a checkbox and click "I accept the terms of use" .

Depends on your definition of "handle"