C# – Remote WMI connection

Note:If you do not specify credentials, the credentials of the running user will be used and so these have to be valid to access the remote computer and usually, this account has to be an admin on the remote box (not for all objects, but just to be sure).

If you are logged in with a domain account, which is valid on both computers, it would work out-of-the-box.

If you are not in a domain environment, just specify credentials.

Try this:

ConnectionOptions co = new ConnectionOptions();
co.Impersonation = ImpersonationLevel.Impersonate;
co.Authentication = AuthenticationLevel.Packet;
co.Timeout = new TimeSpan(0, 0, 30);
co.EnablePrivileges = true;
co.Username = "\\";
co.Password = "";

ManagementPath mp = new ManagementPath();
mp.NamespacePath = @"\root\cimv2";
mp.Server = "";               ///Regard this!!!!

ManagementScope ms = new ManagementScope(mp, co);
ms.Connect();

ManagementObjectSearcher srcd;
srcd = new ManagementObjectSearcher  
(
    ms, new ObjectQuery("select * from Win32_DisplayConfiguration")
);

This is working all the time for me.

From my point of view, the problem occurs, because you are not specifying a remote computer in your ManagementPath. A ManagementPath, created with the defaults, always points to the local machine. And if you just specify credentials to the local computer, this is not allowed and always fails.

br--mabra

First, keep in mind that Microsoft recommends the use of semi-synchronous operations (as Brian suggested):

If you can, we recommend that you use a semi-synchronous operation instead. The performance effect is small, and a semi-synchronous operation allows the same functionality but does not require a reverse connection.

See also Setting Security on an Asynchronous Call in VBScript.

If you still want to use Async operations, refer to the following articles:

• How to troubleshoot WMI-related issues in Windows XP SP2
• Connecting to WMI Remotely Starting with Windows Vista
• Securing a Remote WMI Connection
• Connecting Between Different Operating Systems

YMMV, but for me (Client: Win7 x64 SP1 Server: Windows Server 2008 Enterprise SP2 w/o firewall) the solution for the E_ACCESSDENIED exception was found in the third article:

1. Click Start, click Run, type DCOMCNFG, and then click OK.
2. In the Component Services dialog box, expand Component Services, expand Computers, and then right-click My Computer and click Properties.
3. In the My Computer Properties dialog box, click the COM Security tab.
4. Under Access Permissions, click Edit Limits.
5. In the Access Permission dialog box, select ANONYMOUS LOGON name in the Group or user names box. In the Allow column under Permissions for User, select Remote Access, and then click OK.

Note that I did the above in the client. While that fixed the DCOM permission problem for me, I then encountered WMI access denied errors (0x80041003). Turns out it was due to a registry key mentioned in the second article:

The CIMOM settings need to be updated if the remote connection is between computers that do not have a trust relationship; otherwise, an asynchronous connection will fail. This setting should not be modified for computers in the same domain or in trusted domains.

The following registry entry needs to be modified to allow anonymous callbacks: HKLM\SOFTWARE\Microsoft\WBEM\CIMOM\AllowAnonymousCallback

If the AllowAnonymousCallback key is set to 0, the WMI service prevents anonymous callbacks to the client. If the value is set to 1, the WMI service allows anonymous callbacks to the client.

Note that you need to set the above in the server. Once I did that, async callbacks worked. Other things you could try are running your client as an administrator and setting ConnectionOptions.EnablePrivileges to true.

For troubleshooting see:

• WMI Troubleshooting
• Logging WMI Activity (Pre vista)
• Tracing WMI Activity (Starting with Vista)

Finally, I recommend you take advantage of Microsoft's WMI tester (%windir%\system32\wbem\wbemtest.exe)