XCLN: Troubleshooting Windows Client over Internet

ID: Q161489

The information in this article applies to:

SYMPTOMS

When the Microsoft Exchange client is connecting over the Internet, you receive a message that says "server cannot be found."


CAUSE

Due to firewalls or name resolution issues, the client is unable to attach to Microsoft Exchange Server.


WORKAROUND

To resolve this problem, you need to work on both the client and the server.

On the computer running Microsoft Exchange Server, perform the following steps:

  1. Check the "Services" file in <Windows>\System32\Drivers\etc. This will show the port numbers currently in use.


  2. If you are using a packet filter, you can force Microsoft Exchange Server to use a fixed port for remote procedure calls (RPC). To do this, perform the following steps:

    WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

    For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).


    1. Start Registry Editor (Regedt32.exe).


    2. Under the HKEY_LOCAL_MACHINE subtree, go to the following subkey:
      SYSTEM\CurrentControlSet\Services\MSExchangeDS\Parameters


    3. On the Edit menuc, click Add and add the following information: 
      
      Name: TCP/IP port 
      Type: REG_DWORD 
      Value: "decimal" <port number>. 

      You must also configure the port number in your packet filter.

      NOTE: The <Port Number> may be any number over 1024 and must be in
      decimal format. In addition, the DS and IS Port Number must be different.
 
      For example: "TCP/IP Port"=dword:00000400(1024)

      The number 1024 for the DS above is 400 in hexidecimal format.


    4. For the Information Store, create a registry entry called "TCP/IP port" under the following key:
      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\
      This is a DWORD and the value is "decimal" <port number>.

      NOTE: The <Port Number> may be any number over 1024 and must be in decimal format. In addition, the DS and IS Port Number must be different.

      For example: "TCP/IP Port"=dword:00000402(1026)

      The number used was 1026 for the IS, 402 in hexidecimal format.


    5. Add a registry entry called "TcpipClientSupport" under the following subkey:
      HKEY_LOCAL_MACHINE/System/CurrentControlSet/Control/LSA
      This is a DWORD; set it to Hex 1.


    6. Quit Registry Editor.




  3. Configure your packet filter to allow TCP connections to the ports mentioned above plus port 135 (for the RPC End-Point Mapper service) on the Microsoft Exchange Server-based server.


On the client:

  1. Edit the Lmhosts file to have an entry for the computer running Microsoft Exchange Server. For example: tcp/ip address servername #PRE #DOM:domain name 200.246.248.29 enterprise #PRE #DOM:training


  2. Edit the Hosts file to have an entry for the computer running Microsoft Exchange Server. For example: ipaddress <complete internet host name> 200.246.248.29 enterprise.sao.nutecnet.com


  3. On the Tools menu, click Services, click Exchange Server, click Properties, and click Advanced. Clear the "When Using the network" check box, under Encrypt Information section.


  4. Make sure TCP/IP is first in the Exchange binding order. This procedure varies for the different Windows clients: For 32-bit clients (Windows 95 clients and Windows NT clients):


WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows NT. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. 


   a. Start Registry Editor (Regedt32.exe). 



   b. Under the HKEY_LOCAL_MACHINE subtree, go to the following subkey:


SOFTWARE/Microsoft/Exchange/Exchange Service Provider 



   c. Make sure the RPCBindingOrder value has ncacn_ip_tcp listed first. 



   d. Quit Registry Editor. 



   For 16-bit clients (Windows 3.x clients): 



   a. Open Exchng.ini (in the Windows directory). 



   b. In the [Exchange Provider] section, make sure
Rpc_Binding_order=ncacn_ip_tcp.


REFERENCE



For additional information, please see the following articles in the Microsoft Knowledge Base:

Q149692 XCLN: Error Message When Clients Try to Connect via Internet

Q152725 XCLN: How to Connect over the Internet to an Exchange Server


Also see http://www.microsoft.com/exchange/55/gen/Security.htm

Additional query words: 


Keywords          : kbusage XCLN 
Version           : 4.0
Platform          : WINDOWS 
Issue type        :

Last Reviewed: March 31, 1999