In this article, we will see the Captive portal HTTP/Radius information flow as below.
Note: I did not include the DNS information flow in the above.
Most of the captive portal setup will ask to accept Terms & conditions to have Internet access. On the below page, once you tick the checkbox before accept Terms & Conditions and hit the button "Log in," the user will have Internet access.
The captive portal server's web page will automatically create a username and password for each user device used to track the user device.
Below are the frames captured between the user Device and Access point.
Frame -1: Shows the User connected to the SSID and trying to access the internet.
Frame-2: As the user is not Authenticated or did not accept the Terms & Conditions, the user is redirected captive portal page.
Frame-3: We can see the User trying to access the captive portal page from the Captive portal server ( "server-ip/guest/test-cp.php" is the page URL).
If the Page/captive portal server is not reachable at this stage, we will see an Error saying too many redirects.
Frame-4: Once the page is accessible and the user ticks the checkbox to accept Terms & Conditions and hits Log in button, the web page will automatically create a username and password for each user device. Post/Login frame helps a lot in troubleshooting the captive portal problems.
Once Post /login frame reaches the Access point with the information available on the page, a radius Access request is formed and sent to Radius Server by the Access point.
Frame-5: After Successful authentication user is redirected to Linked.com. If the reachability to the captive portal server and radius are ok, the user should not face any issues in going online.
Comments