RPC over HTTP error keep asking for login

Hello all,

We have a FE-BE 2003 behind an ISA 2000 FW. OWA been working fine for 2-3 years so far, now i'm trying to install the RPC feature but it keeps asking for username and password.

FE name=pluton.company.com
BE name= mercurio.company.com

Outlook 2003 connection is set like:

Basic authentication.
For testing purposes i checked connect using HTTP on fast networks and slow networks.

RPC VD on FE is set to basic and integrated authentication.
Already modified registry with 593, 6001-6004 ports on FE.

When the laptop is in our LAN it connects perfectly to its mailbox wich is placed on mercurio server.

The most curious thing is that Outlook prompts me to authenticate on mercurio instead off on pluton.

Any ideas?


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Does it work internally using RPC/HTTP?

If you open outlook with the /rpcdiag switch, does it show connected with TCP/IP or HTTP?

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RPC over HTTP works fine within the network, as it looks like directly connecting to Exchange Server.

Does your Firewall/ISA have enable for Reverse Proxy for using RPC over HTTP, as I am not sure how to do that but I guess that could be the case.

Also read this article, this may also help

fetillerAuthor Commented:

i'm using outlook 2003 on a windows vista with admin rights and when i try to run outlook /rcpdiag it shows an error. Unkown modifier or something like that.


I don't know either if my FW has reverse proxy enabled for RPC over HTTP but i did all the steps of that article and my BE keeps asking me for username and password.
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In the system tray, hold CTRL and right click the outlook icon - then click connection status - what does it say
Dear Kieran,

This is same like running outlook / rcpdiag.

I guess this is issue with Firewall/ISA/FE Servers

Check in this article, may be some kind of help you get

If you have single server, then check out this

>>This is same like running outlook / rcpdiag.

Yes, I know.  Read the error the asker had "Unkown modifier" either means that /rpcdiag switch doesnt work in vista with 2003, or there was pilot error - either way, there is another way to do it.
fetillerAuthor Commented:
Hmmm i tried that CTRL right click on connection status and it shows:

mercurio.company.com  directory connecting
mercurio.company.com  reference connecting

then both messages dissapears and it shows

marte.company.com   directory   connecting

and then on an alert window.

Server is offline and cannot connect.

Marte is a very old exchange server we had 2-3 years ago, it had the ip on that ip now we have our intranet server. If i ping marte it is resolved on

I've been looking for marte entries on DNS server and wins and did not find any entry, then i checked hosts files and there was an old entry on my FW server. I deleted it and added mercurio.

Guess i need to restart the FW server but i'm out of the office now so i'll do it on monday.


I can resolve marte from any computer on my LAN, am i missing anything else?
How did you setup the servers for RPC/HTTP, which guide did you use?
fetillerAuthor Commented:

i followed these articles:


Btw, FW is already restarted but the problem is still there, our comps still resolving marte.company.com.

there isn't any entry in our DNS nor WINS server. What else should i check?
fetillerAuthor Commented:

There was an entry for marte in a Wins Server located in one of our remote offices wich was resolving marte...

Now everything works! :)
fetillerAuthor Commented:

if you don't mind i'll give 500 points to kieran since their suggestion of running outlook with /rcpdiag - holding CTRL an right clicking on outlook icon and checking connection status is what helped me to find the error.
The MSExchange.org articles on RPC/HTTP are flawed, they were based on the beta versions on everything and are poorly outdated.

I rely on these -> http://www.amset.info/exchange/rpc-http.asp
No worries fetiller, right idea on right time is the only one is looking, giving or taking points is just to motivate you to look on EE.
Thanks for writing to me, appreciated.
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