You can use the UNC path (which starts with \\
) directly in your paths. However, you must account for the credentials for this connection, which can be the tricky part.
There are several approaches:
If the remote system is on the same domain or there is a trust relationship between the domains, and the user your program is running as has suitable access, it will "just work".
You can shell out and execute the net use
command (through the Windows net.exe
program) to make a connection with a specific username and password. Be aware that connection is usable by any program running in the user's session, not just your application. Use the /DELETE
command to remove the connection when you are done. The typical syntax is: net use \\computername\sharename password /USER:domain\username
.
You can P/Invoke WNetAddConnection2
to accomplish the same thing as net use
without shelling out to net.exe
. By passing NULL as lpLocalName
, no drive letter is assigned, but the username and password will apply to subsequent accesses made through the UNC path. The WNetCancelConnection2
function can be used to disconnect.
You can P/Invoke LogonUser
with the LOGON32_LOGON_NEW_CREDENTIALS
flag followed by an impersonation to add additional remote credentials to your thread. Unlike #2 and #3, the effects on the user's entire session will be a little more limited. (In practice, this is rarely done in favor of the well-known WNetAddConnection2
solution.)
The following is a sample of how to call WNetAddConnection2
from VB.NET.
Private Sub Test()
Dim nr As New NETRESOURCE
nr.dwType = RESOURCETYPE_DISK
nr.lpRemoteName = "\\computer\share"
If WNetAddConnection2(nr, "password", "user", 0) <> NO_ERROR Then
Throw New Exception("WNetAddConnection2 failed.")
End If
'Code to use connection here.'
If WNetCancelConnection2("\\computer\share", 0, True) <> NO_ERROR Then
Throw New Exception("WNetCancelConnection2 failed.")
End If
End Sub
<StructLayout(LayoutKind.Sequential)> _
Private Structure NETRESOURCE
Public dwScope As UInteger
Public dwType As UInteger
Public dwDisplayType As UInteger
Public dwUsage As UInteger
<MarshalAs(UnmanagedType.LPTStr)> _
Public lpLocalName As String
<MarshalAs(UnmanagedType.LPTStr)> _
Public lpRemoteName As String
<MarshalAs(UnmanagedType.LPTStr)> _
Public lpComment As String
<MarshalAs(UnmanagedType.LPTStr)> _
Public lpProvider As String
End Structure
Private Const NO_ERROR As UInteger = 0
Private Const RESOURCETYPE_DISK As UInteger = 1
<DllImport("mpr.dll", CharSet:=CharSet.Auto)> _
Private Shared Function WNetAddConnection2(ByRef lpNetResource As NETRESOURCE, <[In](), MarshalAs(UnmanagedType.LPTStr)> ByVal lpPassword As String, <[In](), MarshalAs(UnmanagedType.LPTStr)> ByVal lpUserName As String, ByVal dwFlags As UInteger) As UInteger
End Function
<DllImport("mpr.dll", CharSet:=CharSet.Auto)> _
Private Shared Function WNetCancelConnection2(<[In](), MarshalAs(UnmanagedType.LPTStr)> ByVal lpName As String, ByVal dwFlags As UInteger, <MarshalAs(UnmanagedType.Bool)> ByVal fForce As Boolean) As UInteger
End Function