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How To Add and Remove Network Connections

This article was previously published under Q173011
This article has been archived. It is offered "as is" and will no longer be updated.
This article demonstrates how to programmatically create and remove networkconnections by using Windows API functions. The following example will adda connection to a network share and will disconnect from the same share.
NOTE: This code only includes minimal error trapping. It only reportssuccess or failure of the API calls. Any production use of this code shouldexamine the values returned by the API functions and handle the errorsappropriately. The most common error constants are listed for this purpose.

Steps to Reproduce Behavior

  1. Create a new Standard EXE project.
  2. Add a module to the project.
  3. Copy and paste the following Declares and Type into the module: (NOTE: If you add this to a Form module, make all entries Private.)
          Declare Function WNetAddConnection2 Lib "mpr.dll" Alias _      "WNetAddConnection2A" (lpNetResource As NETRESOURCE, _      ByVal lpPassword As String, ByVal lpUserName As String, _      ByVal dwFlags As Long) As Long      Declare Function WNetCancelConnection2 Lib "mpr.dll" Alias _      "WNetCancelConnection2A" (ByVal lpName As String, _      ByVal dwFlags As Long, ByVal fForce As Long) As Long      Type NETRESOURCE        dwScope As Long        dwType As Long        dwDisplayType As Long        dwUsage As Long        lpLocalName As String        lpRemoteName As String        lpComment As String        lpProvider As String      End Type      Public Const NO_ERROR = 0      Public Const CONNECT_UPDATE_PROFILE = &H1      ' The following includes all the constants defined for NETRESOURCE,      ' not just the ones used in this example.      Public Const RESOURCETYPE_DISK = &H1      Public Const RESOURCETYPE_PRINT = &H2      Public Const RESOURCETYPE_ANY = &H0      Public Const RESOURCE_CONNECTED = &H1      Public Const RESOURCE_REMEMBERED = &H3      Public Const RESOURCE_GLOBALNET = &H2      Public Const RESOURCEDISPLAYTYPE_DOMAIN = &H1      Public Const RESOURCEDISPLAYTYPE_GENERIC = &H0      Public Const RESOURCEDISPLAYTYPE_SERVER = &H2      Public Const RESOURCEDISPLAYTYPE_SHARE = &H3      Public Const RESOURCEUSAGE_CONNECTABLE = &H1      Public Const RESOURCEUSAGE_CONTAINER = &H2      ' Error Constants:      Public Const ERROR_ACCESS_DENIED = 5&      Public Const ERROR_ALREADY_ASSIGNED = 85&      Public Const ERROR_BAD_DEV_TYPE = 66&      Public Const ERROR_BAD_DEVICE = 1200&      Public Const ERROR_BAD_NET_NAME = 67&      Public Const ERROR_BAD_PROFILE = 1206&      Public Const ERROR_BAD_PROVIDER = 1204&      Public Const ERROR_BUSY = 170&      Public Const ERROR_CANCELLED = 1223&      Public Const ERROR_CANNOT_OPEN_PROFILE = 1205&      Public Const ERROR_DEVICE_ALREADY_REMEMBERED = 1202&      Public Const ERROR_EXTENDED_ERROR = 1208&      Public Const ERROR_INVALID_PASSWORD = 86&      Public Const ERROR_NO_NET_OR_BAD_PATH = 1203&						
  4. Add two CommandButtons to Form1. These will be Command1 and Command2 by default.
  5. Add the following code to Form1, substituting a valid share name for "\\ServerName\ShareName":
          Option Explicit      Private Sub Command1_Click()      Dim NetR As NETRESOURCE      Dim ErrInfo As Long      Dim MyPass As String, MyUser As String      NetR.dwScope = RESOURCE_GLOBALNET      NetR.dwType = RESOURCETYPE_DISK      NetR.dwDisplayType = RESOURCEDISPLAYTYPE_SHARE      NetR.dwUsage = RESOURCEUSAGE_CONNECTABLE      NetR.lpLocalName = "X:" ' If undefined, Connect with no device      NetR.lpRemoteName = "\\ServerName\ShareName"   ' Your valid share      'NetR.lpComment = "Optional Comment"      'NetR.lpProvider =    ' Leave this undefined      ' If the MyPass and MyUser arguments are null (use vbNullString), the      ' user context for the process provides the default user name.      ErrInfo = WNetAddConnection2(NetR, MyPass, MyUser, _      CONNECT_UPDATE_PROFILE)      If ErrInfo = NO_ERROR Then        MsgBox "Net Connection Successful!", vbInformation, _        "Share Connected"      Else        MsgBox "ERROR: " & ErrInfo & " - Net Connection Failed!", _        vbExclamation, "Share not Connected"      End If      End Sub      Private Sub Command2_Click()      Dim ErrInfo As Long      Dim strLocalName As String      ' You may specify either the lpRemoteName or lpLocalName      'strLocalName = "\\ServerName\ShareName"      strLocalName = "X:"      ErrInfo = WNetCancelConnection2(strLocalName, _      CONNECT_UPDATE_PROFILE, False)      If ErrInfo = NO_ERROR Then        MsgBox "Net Disconnection Successful!", vbInformation, _        "Share Disconnected"      Else        MsgBox "ERROR: " & ErrInfo & " - Net Disconnection Failed!", _        vbExclamation, "Share not Disconnected"      End If      End Sub						
Run the project and click on Command1. You will get a Message dialogindicating success or failure. If successful, you should be able to look inWindows Explorer and see the new connection (unless you left lpLocalNameundefined, in which case the connection does not show in Explorer). ClickCommand2 and go to Explorer, where you should see that the connection hasbeen removed.
For information about limitations using WNetAddConnection2 on differentWindows platforms, please see the following article in theMicrosoft Knowledge Base:
183366 : INFO: WNetAddConnection2 and Multiple User Credentials

For more information, please Search on the following topics in either theWin32 Programmer's Reference or The Microsoft Developer Network LibraryCD-ROM:
  • WNetAddConnection2
  • WNetCancelConnection2
kbDSupport kbdsd kbVBp400 kbVBp500 kbNetGrp kbnetwork kbAPI kbWNet KBWIN32SDK kbVBp600 kbVBp

Article ID: 173011 - Last Review: 12/04/2015 17:41:58 - Revision: 2.1

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