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There seems to be some protocol by which operating systems automatically launch the login page upon connecting to the WiFi network. Unfortunately, it seems to f

There seems to be some protocol by which operating systems automatically launch the login page upon connecting to the WiFi network. Unfortunately, it seems to fail pretty often and probably doesn't work for bridged connections.

libeclipse 10y ago
On Nougat it seems to work flawlessly most of the time. I wonder what the protocol is. Maybe a request to the access point's DNS server to see what IP is returned and then connect to that?
JimDabell 10y ago
There's no standard protocol in widespread use. Typically operating systems attempt to fetch a known resource when connecting to a new Wi-Fi network, and if it redirects, then they treat the destination as the captive portal sign-in page and display it with special chrome / modally. The URL each platform attempts to load varies by vendor and version.
- ethagnawl 10y ago
  Do you have any links to resources or know what name(s) people use when talking about this strategy? I'd be interested to know which URL Debian attempts to fetch, but I'm not sure how I'd even begin to search for the answer.
  - kalleboo 10y ago
    "Captive portal detection" And here's your answer: http://network-test.debian.org/nm http://network-test.debian.org/nm
    - ethagnawl 10y ago
      Thanks!
  - jlgaddis 10y ago
    cf. http://blog.erratasec.com/2010/09/apples-secret-wispr-request.html http://blog.erratasec.com/2010/09/apples-secret-wispr-reques...
brainfire 10y ago
My understanding is that this is just the OS trying to fetch a known page over HTTP and, if redirected, assuming it got a login portal and presenting it to the user. I assume this can continue "working" (with your noted caveat that it doesn't even always work today) forever, as the process that checks doesn't need to understand HSTS or to ever try HTTPS, regardless of what actual web browsers start doing.
rcthompson 10y ago
Basically, they try to phone home and if it redirects, they assume it's a captive portal login page. It's a sort of controversial practice, because it means that the OS vendor now always knows where and when you're accessing the internet.

libeclipse 10y ago

On Nougat it seems to work flawlessly most of the time. I wonder what the protocol is. Maybe a request to the access point's DNS server to see what IP is returned and then connect to that?

JimDabell 10y ago

There's no standard protocol in widespread use. Typically operating systems attempt to fetch a known resource when connecting to a new Wi-Fi network, and if it redirects, then they treat the destination as the captive portal sign-in page and display it with special chrome / modally. The URL each platform attempts to load varies by vendor and version.

ethagnawl 10y ago
Do you have any links to resources or know what name(s) people use when talking about this strategy? I'd be interested to know which URL Debian attempts to fetch, but I'm not sure how I'd even begin to search for the answer.
- kalleboo 10y ago
  "Captive portal detection" And here's your answer: http://network-test.debian.org/nm http://network-test.debian.org/nm
  - ethagnawl 10y ago
    Thanks!
- jlgaddis 10y ago
  cf. http://blog.erratasec.com/2010/09/apples-secret-wispr-request.html http://blog.erratasec.com/2010/09/apples-secret-wispr-reques...

brainfire 10y ago

My understanding is that this is just the OS trying to fetch a known page over HTTP and, if redirected, assuming it got a login portal and presenting it to the user. I assume this can continue "working" (with your noted caveat that it doesn't even always work today) forever, as the process that checks doesn't need to understand HSTS or to ever try HTTPS, regardless of what actual web browsers start doing.

rcthompson 10y ago

Basically, they try to phone home and if it redirects, they assume it's a captive portal login page. It's a sort of controversial practice, because it means that the OS vendor now always knows where and when you're accessing the internet.