Users cannot connect to remote desktops by using the Windows Small Business Server 2003 Remote Web Workplace

When users try to connect to a remote desktop on a Microsoft Windows Small Business Server 2003-based network by using a Remote Web Workplace connection, they receive the following error message: This issue occurs when users click Connect to Server Desktops or Connect to Client Desktops on the Remote Web Workplace site and then try to connect to one of the server desktops or client desktops in the list.

This issue may occur if a process that is running on the Windows Small Business Server-based computer is listening on Transmission Control Protocol (TCP) port 4125. On a Windows Small Business Server-based computer, the Remote Web Workplace uses TCP port 4125 for its remote desktop feature. Sometimes, another process may use TCP port 4125 before Remote Web Workplace can claim port 4125. If another process is listening on this port, Windows Small Business Server cannot respond to the remote computer's connection request.

The most common process that claims TCP port 4125 is Mad.exe. Mad.exe is the Microsoft Exchange System Attendant service.

To resolve this issue, determine which process is listening on port 4125, and then stop that process from listening on that port. To do this, follow these steps:

1. On the Windows Small Business Server computer, click Start, click Run, type cmd, and then click OK.
2. Type the following command, and then press ENTER:
   netstat -aon | find ":4125"
   You receive results that are similar to the following:
   TCP IP_Address:Port IP_Address:Port LISTENING Process_Identifier
   Note The Process_Identifier (ID) that appears in these results is the ID of the process that is listening on port 4125.
3. Right-click the taskbar, and then click Task Manager.
4. Click the Processes tab, and then click Select Columns on the View menu.
5. Click to select the PID (Process Identifier) check box, and then click OK.
6. On the Processes tab, locate the service that corresponds to the process ID that was returned by the netstat command.
7. Restart the service that corresponds to this process. For example, if the process is Mad.exe, restart the Microsoft Exchange System Attendant service. To do this, follow these steps:
   1. Click Start, click Run, type services.msc, and then click OK.
   2. Double-click the service that you want to restart, make sure that the name of the process appears in the Path to executable box on the General tab, and then click Cancel.
   3. Right-click the service, and then click Restart.
   4. If you are prompted to also restart one or more dependent services, click Yes.
   Note If this service has stopped responding, you may have to end the process by using Windows Task Manager. To do this, click the process in question, click End Process, and then click Yes.

If you experience this problem with the Mad.exe process, you can modify the port range that is used by the remote procedure call (RPC) protocol to exclude port 4125. To do this, follow these steps.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry subkey:
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc
3. Right-click Rpc, point to New, and then click Key.
4. In the New Key #1 box, type Internet, and then press ENTER.
5. Create the following three registry entries:
   Entry name: Ports
   Type: REG_MULTI_SZ
   Value data: 4125
   
   Entry name: PortsInternetAvailable
   Type: REG_SZ
   Value data: N
   
   Entry name: UseInternetPorts
   Value type: REG_SZ
   Value data: Y
   To do this, follow these steps:
   1. Right-click Internet, point to New, and then click Multi-String Value.
   2. In the New Value #1 box, type Ports, and then press ENTER.
   3. Right-click Ports, and then click Modify.
   4. In the Value data box, type 4125, and then click OK.
   5. Right-click Internet, point to New, and then click String Value.
   6. In the New Value #1 box, type PortsInternetAvailable, and then press ENTER.
   7. Right-click PortsInternetAvailable, and then click Modify.
   8. In the Value data box, type N, and then click OK.
   9. Right-click Internet, point to New, and then click String Value.
   10. In the New Value #1 box, type UseInternetPorts, and then press ENTER.
   11. Right-click UseInternetPorts, and then click Modify.
   12. In the Value data box, type Y, and then click OK.
6. Quit Registry Editor, and then restart the Windows Small Business Server computer.

This issue may also occur if you have a router or a firewall that is configured between the Windows Small Business Server computer and a client computer. In this scenario, verify that the router or the firewall is configured to permit traffic on TCP port 4125 to the Windows Small Business Server computer. For additional information about how to configure or troubleshoot network connectivity issues, click the following article numbers to view the articles in the Microsoft Knowledge Base: