Members Only Plugin to be skipped when using proxy

Hi all,

Thanks for any help to start with. I’m running WP as a intranet, so I’m not able to show you the page.

My situation:
We’re running WP (3.1) on a MS IIS server (7.0) and it’s all working very smoothly. We’re authenticating our users with the LDAP authenticate plugin against our LDAP server. Works fine.

What I need to happen:
I’d like to open up WordPress to the outside world (internet), but obviously I’d like to put a username/password authentication before anything.

Members Only plugin seems to do the trick, but the problem is that internal users need to authenticate as well. We rather have a system that detects the internal proxy, so internal staff don’t have to worry about authentication if they don’t want to.

Does anyone have any idea?