I use Fedora quite a bit. Mostly for Gnome-shell, but it's handy to have for testing some other things as well. Since Fedora 22 (this still happens on fc23), I've noticed a strange event where upon login I am presented with a maximized white window. The title bar of this window says "Web Authentication Redirect", and the body will either be blank or say something like "connection refused". The big problem here is, I could no longer click on anything, switch tasks, or use my keyboard.
Doing a little bit of Googling, I see some other people will occasionally get this screen but may see the gnome.org homepage instead of being blank. It seems that a lot of people didn't have any solutions for this however.
After a bit more digging, I discovered this commit:
Add a helper to handle captive portal logins Add a small DBus-activated GtkApplication that embeds a WebKitWebView and implements some minimal logic to see if the login succeeds. It will try to connect to a custom NM-provided url (the portal login page), if one exists, or to www.gnome.org in the normal case of a portal doing redirect.
Sadly, I was unable to switch to a console using 'ctrl' + 'alt' + 'fN', however I did have ssh enabled and I was able to ssh in from another machine. Once in, I did a quick look for the portal process.
$ ps aux | grep ninja | grep -i portal ninja 19111 0.0 0.2 2289916 64712 tty2 Sl+ 2015 0:00 /usr/libexec/gnome-shell-portal-helper
Killing this process seemed to do the trick
$ kill 19111
I still wasn't able to type with my keyboard, however, so I restarted my Gnome-shell over the ssh connection:
$ gnome-shell --replace
Success! At least now I have access to my machine again, and I didn't have to wreck my uptime to get it.