HOW TO: Access the Registry on a Remote Computer by Using Visual Basic 6.0 and the Windows API

Summary

This article explains how to use a Visual Basic application to access the registry on a remote computer in conjunction with the Windows application programming interface (API).

Requirements

You need the following hardware and software to perform the procedures in this article:

  • A Microsoft Windows XP, Microsoft Windows 2000, or Microsoft Windows NT 4.0-based computer
  • Visual Basic 6.0
NOTE: If the remote registry is on a system that is running Windows NT 4.0, Windows 2000, or Windows XP, you must run the code from an account that has permission to read that registry.

You also need the following skills:

  • Visual Basic 6.0 programming experience
  • Familiarity with the Windows registry

Create a Demonstration Application

  1. Start Visual Basic 6.0, and then create a new project of type Standard EXE.
  2. Right-click the form, and then click View Code on the Shortcut menu. Add the following statement at the start of the code:
    Option Explicit
  3. Add the following code to declare the constants used to access the registry:
    Private Const HKEY_CLASSES_ROOT = &H80000000
    Private Const HKEY_CURRENT_USER = &H80000001
    Private Const HKEY_LOCAL_MACHINE = &H80000002
    Private Const HKEY_USERS = &H80000003

    Private Const KEY_QUERY_VALUE = &H1
    Private Const KEY_SET_VALUE = &H2
    Private Const KEY_ALL_ACCESS = &H3F

    Private Const REG_SZ As Long = 1
    Private Const ERROR_SUCCESS = 0&
  4. Add the following code to declare the entry points for the registry functions in the Windows application programming interface (API):
    Private Declare Function RegConnectRegistry Lib "advapi32.dll" _
    Alias "RegConnectRegistryA" _
    (ByVal lpMachineName As String, _
    ByVal hKey As Long, _
    phkResult As Long) As Long

    Private Declare Function RegCloseKey Lib "advapi32.dll" _
    (ByVal hKey As Long) As Long

    Private Declare Function RegOpenKeyEx Lib "advapi32.dll" _
    Alias "RegOpenKeyExA" _
    (ByVal hKey As Long, _
    ByVal lpSubKey As String, _
    ByVal ulOptions As Long, _
    ByVal samDesired As Long, _
    phkResult As Long) As Long

    Private Declare Function RegQueryValueExString Lib "advapi32.dll" _
    Alias "RegQueryValueExA" _
    (ByVal hKey As Long, _
    ByVal lpValueName As String, _
    ByVal lpReserved As Long, _
    lpType As Long, _
    ByVal lpData As String, _
    lpcbData As Long) As Long
  5. Add the following global variable declaration:
    Private hRemoteReg As Long
  6. Add the following code to handle the Form_Load event. This code calls the RegConnectRegistry function to connect to the remote registry. Replace the \\RemoteMachineName parameter with the name of the computer whose registry you want to access:
    Private Sub Form_Load()
    Dim lRet As Long

    'Connect to the remote registry
    lRet = RegConnectRegistry("\\RemoteMachineName", _
    HKEY_LOCAL_MACHINE, _
    hRemoteReg)

    If (lRet = ERROR_SUCCESS) Then
    MsgBox "Successfully connected to remote registry"
    Else
    MsgBox "Error:" & Err.LastDllError
    Unload Me
    Exit Sub
    End If
    End Sub
  7. Add the following code to handle the Form_Unload event:
    Private Sub Form_Unload(Cancel As Integer)
    Dim lRet As Long
    If hRemoteReg <> 0 Then
    lRet = RegCloseKey(hRemoteReg)
    End If
    End Sub
  8. In the Form Designer, add a Command control to the form. The control has the default name of Command1.
  9. Double-click Command1 to create a click handler for the command button. Add the following code to the click handler function:
    Private Sub Command1_Click()
    Dim lRetVal As Long
    Dim hKey As Long
    Dim sValue As String

    lRetVal = RegOpenKeyEx(hRemoteReg, _
    "HARDWARE\DESCRIPTION\System", 0, KEY_QUERY_VALUE, hKey)
    If lRetVal <> ERROR_SUCCESS Then
    MsgBox "Cannot open key"
    Else
    sValue = String(255, " ")
    lRetVal = RegQueryValueExString(hKey, _
    "SystemBIOSVersion", 0&, REG_SZ, sValue, 255)
    If lRetVal <> ERROR_SUCCESS Then
    MsgBox "Cannot query value"
    Else
    MsgBox sValue
    End If
    lRetVal = RegCloseKey(hKey)
    If lRetVal <> ERROR_SUCCESS Then
    MsgBox "Cannot close key"
    End If
    End If
    End Sub

Verification

  1. Press F5 to build and run the application.
  2. A message box appears, indicating that the registry on the remote computer has been contacted. Click OK.

    The main form of the application appears.
  3. Click Command1. The value stored in the following location in the remote registry is displayed:
    HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\SystemBIOSVersion
  4. To verify this registry value, run regedit.exe on the remote computer. In Registry Editor, click Find on the Edit menu. Type SystemBIOSVersion, and then click Find Next. After a short pause, Registry Editor displays the value for this key; verify that this is the same value displayed in your Visual Basic application.

References

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

145679 HOWTO: Use the Registry API to Save and Retrieve Setting
Properties

Article ID: 315586 - Last Review: Oct 26, 2002 - Revision: 1

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