Outlook Web Access (Exchange) with ...

I needed a way to authenticate users from our library from a server outside our network, and therefore also not connected to Active Directory. At first I was thinking LDAP would be the best way...then I did my research and learned enough about LDAP to realize just how much information it gives out - WAY too much for it to be very secure. Even if I used SSL, created an account specifically for this access, set that account to read only...all it would take would be one person to hack our server and grab that information and all our organization's data is out there. Although it's about as much of a chance as getting hit by lightning in the middle of the desert in a sand storm, I wouldn't want to be responsible.

The only server with any sort of external web presence that is also touching the internet is our Exchange server's web access portal. I thought, "Ah HA! I can use cURL, or streams, or fsockopen or something to fake a login to this page to verify authentication!" After searching a bit (I'm terrible every time I attempt to write something using cURL to authenticate), I came across a few things.

1. Exchange Server 2007 uses SOAP to provide a web service...AWESOME! We currently use 2003 though, but we will be upgrading later this year, so this may be helpful later on. [Link]
   1. HowToForge article on how to use PHP with 2007's SOAP Web Service
2. I found this PHP script that I tested, which successfully contacted our OWA server and authenticated.
3. I also found a PHP class on Google Code from Tyler Hall - it's not any particular project repository, just miscellaneous code he's hosting. It looks like it's slightly more feature rich, allowing info from address books and a user's inbox, for example.

I only needed to authenticate our building, so thankfully we had our own subdomain (not sure of the proper terminology) in the AD... If your domain was example.com (DC=example,DC=com), just getting OUR office (assume "Office1") was as easy as defining office1.example.com (DC=office1,DC=example,DC=com) after the @ symbol in the user's username (typically unnecessary information with OWA, but adding it explicitly was important here). It (seemingly) worked perfectly.

If you plan on doing something similar, just make sure that you cache (and encrypt) username/password information locally, hitting the OWA page continuously would probably make your System (or Email) Administrators a little unhappy with you.