If you plan to use the securepages module behind a proxy that terminates SSL, there are some additional server configuration steps you need to take.
In order to detect what the protocol is in use, securepages tests the value of $_SERVER['HTTPS']. Out of the box, this merely reflects the immediate connection to your proxy. If this protocol differs from that used by the original client, then securepages can't work (the most likely outcome is a redirect loop).
To resolve this, you'll need to ask your proxy to send the X-Forwarded-Proto header. While you're free to use any header label you choose, X-Forwarded-Proto seems to have become the de facto standard.
