I've found http://neverssl.com very helpful for captive portals. It does what you'd expect - hosts a HTTP-only page that allows captive portals to work correctly.
Since it's only ever HTTP, it sidesteps the certificate errors or HTTP downgrades that normal sites are hit with during captive portal interception.
I am curious what happens to captive portals as HTTPS adoption rises. Some OS's (Android, OSX) already detect captive portals and launch a lightweight webview.
Yep, I use neverssl.com, when I remember it. Though, mostly I use example.com, since that works without SSL as well. I guess now I'll need to remember to type http://example.com .
Based off my experience, more and more captive portals appear to be letting the requests the OS makes to captive.apple.com or whatever through but still try to present a captive portal to the user. I can guess as to the motivation, but as a user it's danged annoying.
Since it's only ever HTTP, it sidesteps the certificate errors or HTTP downgrades that normal sites are hit with during captive portal interception.
I am curious what happens to captive portals as HTTPS adoption rises. Some OS's (Android, OSX) already detect captive portals and launch a lightweight webview.