For migration, I had 2010 and 2013 co-existence and then removed the 2010 server. Now left with a single 2013. Using forms based authentication (FBA) and going through a Sophos UTM for all external access. With 2010, access from the Internet to OWA was perfect.
Now with 2013, when accessing http://EXTERNAL.URL/owa from outside, Exchange redirects the FBA login page to https://INTERNAL.URL/owa/auth/logon.aspx?replaceCurrent=1&url=https%3a%2f%2fINTERNAL.URL%2fowa%2f%3fauthRedirect%3dtrue
So far I tried almost every combination of InternalUrl and ExternalUrl in the OwaVirtualDirectory (even having one or both of them emtpy). Nothing keeps Exchange from redirecting my external URL.
Setting DisableSSORedirects to "true" in <ExchangeSetupDir>\FrontEnd\HttpProxy\owa\web.config as described in http://blog.dargel.at/2013/07/10/exchange-2013-cu2-released/ doesn't help either. It gives me a "500 - Internal server error".
This drives me nuts... Anybody who could help?
Thanks,
Peter