not true. most captive portals work using a redirect. The first time a new device tries to request a webpage, the network gateway will intercept that traffic an

not true. most captive portals work using a redirect. The first time a new device tries to request a webpage, the network gateway will intercept that traffic and reply with some sort of HTTP redirect (perhaps a 303?). This will cause the browser to request a new page with a new URL. Following the redirect, the address bar will show the URL of the captive portal -- not that of the original page requested.