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Redirecting OWA URL in Exchange 2010

Redirecting requests that don’t go to https://owa.customer.com/owa (or /exchange) to the correct URL. So, if someone goes to http://owa.customer.com orhttps://owa.customer.com, they get redirected to the correct (secure) URL. Historically I’ve always done this with two components:

• A custom website listening on Port 80 on each CAS server
• A default.aspx file in the root of the Default Web Site redirecting to /owa

This approach no longer works with Exchange 2010 CAS because the PowerShell virtual directory actually operates over Port 80 (authentication is Kerberized). If you try and tinker with this, you’ll start getting errors from Remote PowerShell like this:

VERBOSE: Connecting to casarray01.customer.com
[casarray01.customer.com] The WinRM service cannot process the request because the request needs to be sent to a different machine. Use the redirect information to send the request to a new machine.  Redirect location reported: https://owa.customer.com/owa/PowerShell. To automatically connect to the redirected URI, verify “MaximumConnectionRedirectionCount” property of session preference variable “PSSessionOption” and use “AllowRedirection” parameter on the cmdlet.
+ CategoryInfo          : OpenError: (System.Manageme….RemoteRunspace:RemoteRunspace) [], PSRemotingTransportRedirectException
+ FullyQualifiedErrorId : PSSessionOpenFailed

In order to work around this, you need to use the HTTP Redirection feature in IIS (the default.aspx trick mentioned above should work too), as well as remove the requirement for SSL at the top level Default Web Site object. You have to be careful doing this because when you set settings on the web site, IIS will push them down to any virtual directory below which does not explicitly set that setting itself. To setup the redirect, select the Default Web Site in IIS Manager, and open the HTTP Redirect option under IIS. Complete it like this:

Once this step is complete, you need to remove the enforced redirect from each of the virtual directories under the Default Web Site. To do this, select each virtual directory individually, and then open the HTTP Redirect property and uncheck the “Redirect requests to this destination” checkbox. You’ll need to do this on the following virtual directories:

• aspnet_client
• Autodiscover
• ecp
• EWS
• Microsoft-Server-ActiveSync
• OAB
• PowerShell
• Rpc

If at this point you simply browse to http://casarray01.customer.com, you’ll get an HTTP 403.4 error. This is because SSL is required at the top-level website. In order to get the redirect working, we need to disable SSL for the toplevel website while leaving it enabled for the relevant child virtual directories.

Select the Default Web Site and open the SSL Settings properties. Uncheck the Require SSL checkbox as shown below:

Like the redirection settings, this change will be inherited down the tree for any virtual directory which does not explicitly set the setting independently. Ensure that SSL is required for the following virtual directories:

• Autodiscover
• ecp
• EWS
• Microsoft-Server-ActiveSync
• OAB
• owa
• Rpc

Once you’ve configured the redirection and SSL settings, open a command prompt and run iisreset. At this point you should be able to browse to http://localhost on the CAS server and get redirected to https://owa.customer.com/owa. These steps were tested on Windows Server 2008 R2. While they should be similar under Windows Server 2008, they may not be identical.

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Categorised as: Exchange, Microsoft, Networking, Outlook, Server OS