I am trying to set up a two-layer proxy for public mobile devices, offering transparent access for the mobile devices that are too stupid to auto-detect proxy settings via proxy.pac / wpad .
I want an easy way for end-users to find out if their device is using transparent or auto-detected settings, after they have connected to the public wireless with no password. The only way I can see for doing that is to have a splash page that attempts an HTTPS connection when they first connect, using that to find out if auto-detect worked or not. And if it fails, then I can have a way to direct them to IT support to see what needs to be done to get proxied access working. I don't really like this method though, because if they are on the transparent proxy, there will be a long delay until the HTTPS attempt finally times out and fails. Is there some established way to for a splash page to quickly identify if transparent or auto-detect proxy settings are being used? Can a web browser page somehow interact with the squid cache to discover this? - Dale Mahalko
