We have been testing using the Global HTTP Proxy with the Squid proxy. Our test with iOS 8 seemed to go well until iOS 9 was released.
What we discovered is following the 8>9 upgrade (and now the 9 > 9.0.3 upgrade), the proxy settings would constantly ask for re-authentication, even though the authentication was being provided by the Configuration Profile pushed through Casper.
As you can see below, the settings are very basic.
But following the upgrade we get this message on any page that isn't configured to bypass the proxy:
We have the following completely bypass the proxy: Casper Server and all of Apple (including APNS ports). I maintain MDM/APNS connections when this issue happens, so I can perform actions on the device.
To resolve, I can remove the device from the scope, watch it remove, and re-apply the same configuration profile and everything works (until the next upgrade).
I can also manually type in the credentials and it begins authenticating again. But that isn't an ideal solution either as we would prefer to not distribute that information any further than necessary.
Does anyone have any experience with this issue specifically or ideas where we can look to resolve this? I don't want to have to create a new Smart Group and Configuration profile for each OS Upgrade on 2,000 iPads just to keep proxy authentication working.