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  • RPC Over Http Strange Issues

    I am running SBS2003 and have implemented RPC over HTTP which mostly works fine.. It works great but its just every so often it seems to stop connecting. Basically outlook will sit there and keep saying "Trying to connect" and the connection status is saying its trying to connect.

    At this point I have used my mobile to get an internet connection and I can generally connect fine first time.

    I have tried everything I could find and im smacking my head against the wall now as it is so intermittent.

    The server is patched up and is also running a blackberry enterprise server.

    Has anyone else had a similar problem? could it be to do with NAT screwing up?

    Kind Regards

    Matt

  • #2
    Re: RPC Over Http Strange Issues

    NAT or firewall is the first place I would be looking.
    However have you run the SBS best practises tool on the server? That can flag network configuration issues on the server that have been known to cause problems in the past.

    Simon.
    --
    Simon Butler
    Exchange MVP

    Blog: http://blog.sembee.co.uk/
    More Exchange Content: http://exchange.sembee.info/
    Exchange Resources List: http://exbpa.com/
    In the UK? Hire me: http://www.sembee.co.uk/

    Sembee is a registered trademark, used here with permission.

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    • #3
      Re: RPC Over Http Strange Issues

      Thanks for the reply ..

      Is there a wizard for the best practises the only I ever found just shows a help file to go through?

      I have also found that reseting the users router their end seems to cure the problem temporarily.

      Kind Regards

      Matt

      Comment


      • #4
        Re: RPC Over Http Strange Issues

        Sorry just found it .. for people who need it :

        http://www.microsoft.com/downloads/d...displaylang=en

        Running it now.

        Matt

        Comment


        • #5
          Re: RPC Over Http Strange Issues

          I have run the best practises and all it gave me was the offloading SP2 prob registry entry to change.. did not make any difference.

          rpcping works successfully.. but while this is working it still is saying trying to connect.

          I also noticed in the http logs that there are entries showing that the server is trying to connect from port 80 on itself to port 593 (RPC) and gives a 400 error (Bad Request) as i say it works for some people and not others.. not sure how to fix this one as running a rpccfg /hd brings up the correct ports.

          Still scratching my head..

          Any help .. ideas .. gratefully recieved.

          Regards

          Matt

          Comment


          • #6
            Re: RPC Over Http Strange Issues

            The usual reason for repeated authentication prompts is an authentication mismatch. Integrated/NTLM set on the /rpc virtual directory and basic set in Outlook or vice versa.

            Simon.
            --
            Simon Butler
            Exchange MVP

            Blog: http://blog.sembee.co.uk/
            More Exchange Content: http://exchange.sembee.info/
            Exchange Resources List: http://exbpa.com/
            In the UK? Hire me: http://www.sembee.co.uk/

            Sembee is a registered trademark, used here with permission.

            Comment


            • #7
              Re: RPC Over Http Strange Issues

              I understand that but it will work fine sometimes then about 3pm uk time it starts being inconsistant and not letting some people on at all. Then if left alone overnight people can get in fine again.

              Is there a connection limit for RPC? but then saying that all we have is a max of 20 people trying to connect at one time.

              Regards

              Matt

              Comment


              • #8
                Re: RPC Over Http Strange Issues

                There is no limit on the number of connections possible. Hosted Exchange providers use RPC over HTTPS exclusively without any issues. Certainly 20 users will not be a problem.

                I would suspect that the problem is elsewhere.

                Did you make the changes to the network configuration that the BPA tool suggested?
                Have you checked that you are using the latest NIC drivers?

                I have also seen similar problems caused by firewalls, where they are not ending the session correctly. I would also suggest that you check you have the latest firmware for that.

                Simon.
                --
                Simon Butler
                Exchange MVP

                Blog: http://blog.sembee.co.uk/
                More Exchange Content: http://exchange.sembee.info/
                Exchange Resources List: http://exbpa.com/
                In the UK? Hire me: http://www.sembee.co.uk/

                Sembee is a registered trademark, used here with permission.

                Comment


                • #9
                  Re: RPC Over Http Strange Issues (Fixed!)

                  I think we finally fixed it..

                  After setting up a trace to monitor traffic to server we found for some reason that there were machines trying to connect to the dcom ports of the server (over the internet .. maybe bots of some sort) through the RPC over HTTP system. This is documented by MS as being a possible security hole so we closed down the dcom ports and specified those ports to be blocked on the firewall. Stopping the dcom ports to outside world unaffects Outlook connecting and since Friday we have been very stable.

                  By attacking the Dcom ports it effectivily created a DOS attack and caused the server to reject connections. (Well thats what we think!)

                  I hope this might help someone else who may get similar probs.

                  Kind Regards

                  Matt

                  Comment


                  • #10
                    Re: RPC Over Http Strange Issues

                    Can you post the link to the MS article.

                    Comment


                    • #11
                      Re: RPC Over Http Strange Issues

                      Here it is:

                      http://support.microsoft.com/kb/826382

                      we also hardened the firewall as we found that although the firewall was setup the virtual server setup was allowing some stuff through the firewall.

                      I.E. only allow specified stuff in and out (basic firewall stuff I know ;o) )

                      Regards

                      Matt

                      Comment


                      • #12
                        Re: RPC Over Http Strange Issues

                        Thanks for posting the link.

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