RPC over HTTP (not HTTPS) in Outlook/Exchange 2003 environment

[Phil Rzewski]

I am trying to get the RPC over HTTP mode working in an
Outlook/Exchange 2003 environment. I am trying to get it
to work with HTTP transport (not HTTPS), and all the
documentation seems to assume one would only ever want it
to be HTTPS, so I fear I'm in uncharted waters.

My server is Windows 2003 Enterprise Server running
Exchange 2003 Server plus SP1. I followed the
instructions at http://support.microsoft.com/?id=833401
to configure the RPC service. My client is XP plus SP1
running Office Professional 2003. I installed the fix at
http://support.microsoft.com/default.aspx?kbid=331320 and
the "Exchange over the Internet" settings appear in my
Outlook 2003.

For my "Exchange Proxy Settings" in the client, I found
that the only way to get the URL to be an "http://"
prefix (instead of "https://") is to use NTLM
Authentication and uncheck "Connect using SSL only".
Unfortunately, when configured in this manner, when I
start up Outlook, I am prompted for credentials and they
do not work: The prompt for credentials keeps coming back
again and again.

Looking at the Troubleshooting section of the
configuration document, reference is made to adding a
registry key "EnableRPCTunnelingUI" under the subkey
HKEY_CURRENT_USER\Software\Microsoft\Office\11.0
\Outlook\RPC . However, that "RPC" subkey doesn't even
exist on my client system. I'm not sure why mine doesn't
have it (I have Outlook Professional 2003), but all
articles on the topic speak of it as if it should
automatically be there. I'm also not sure if this is the
source of my problems, or if I'm doing something else
wrong.

Does anyone have ideas? Thanks.

 

[neo [mvp outlook]]

The reason you feel that you are in uncharted territory is that the default
configuration of the RPC proxy is not to allow anonymous connections. Since
you have Windows 2003, there is no additional cost on your part to setup an
internal CA and secure things properly.

 

[Phil Rzewski]

Thanks for the consideration. However, I do have reasons
for wanting to get this working over HTTP rather than
HTTPS. Considering that the feature is almost always
referred to as "RPC over HTTP", it would be great if the
docs at least briefly covered the configuration of it
working over HTTP.

In any case, your post did give me the idea to try re-
checking the "Enable anonymous access" box for the
Authentication Methods of the Rpc directory in IIS. Alas,
the behavior is the same: Outlook still does not accept
my credentials when I launch.

 

[neo [mvp outlook]]

Did you add the AllowAnonymous registry value (this one goes under the
RPCProxy folder).

HKLM\Software\Microsoft\Rpc\RpcProxy
Value: AllowAnonymous
DWORD: 0 or 1

0 (or value missing) = RPC connection must be over SSL
1 = Anonymous is allowed (I repeat... this is setting is *not* recommended
by Microsoft for Internet facing systems. Should only be implemented in
closed networks.)

 

[Phil Rzewski]

Thank you! That did the trick.

And yes, this is all happening on a closed network. I
agree that this would not be recommended on Internet-
facing systems.