How to use rasphone.exe to get vpn connection without always prompting for password - vb.net

Question

I have an app that connects a Windows VPN (not OpenVPN) using the rasphone.exe interface. I can successfully establish the connection but It prompts for the password each time. Is there a way to get the interface to remember the password so that if the connection is lost the connection can automatically be re-established programatically? As a note when I start the process for rasphone.exe I'm getting exceptions when I try to pass more than 1 parameter to it. The only parameter I can successfully pass is the entry name, I can't add parameters like -d, -h, or -f.
Here is the code I have:
Imports System.Linq
Imports System.Net.NetworkInformation
Public Class clsVPN
Public Delegate Sub delPing()
Public Delegate Sub delConnect()
Public Delegate Sub delIdle()
Public Delegate Sub delDisconnect()
Public Delegate Sub delStatus(blnConnected As Boolean)
Public Event Ping As delPing
Public Event Con As delConnect
Public Event Discon As delDisconnect
Public Event Idle As delIdle
Public Event StatusChanged As delStatus
Public strRASPhone As String = "C:\WINDOWS\system32\rasphone.exe"
Public strIPAddress As String = ""
Public strVPNCon As String = ""
Public blnConnected As Boolean = False
Dim file As String = "C : \Users\Tom\AppData\Roaming\Microsoft\Network\Connections\Pbk\rasphone.pbk"
Protected Sub OnStatusChanged(blnConnected As Boolean)
RaiseEvent StatusChanged(blnConnected)
End Sub
Protected Sub OnDisconnect()
RaiseEvent Discon()
End Sub
Protected Sub OnPing()
RaiseEvent Ping()
End Sub
Protected Sub OnIdle()
RaiseEvent Idle()
End Sub
Protected Sub OnConnect()
RaiseEvent Con()
End Sub
Public ReadOnly Property Connected() As Boolean
Get
Return blnConnected
End Get
End Property
Public Property ConName() As String
Get
Return strVPNCon
End Get
Set(strValue As String)
strVPNCon = strValue
End Set
End Property
Public Function Test() As Boolean
Dim blnSucceed As Boolean = False
OnPing()
Dim p As New Ping()
If p.Send(strIPAddress).Status = IPStatus.Success Then
blnSucceed = True
Else
blnSucceed = False
End If
p = Nothing
If blnSucceed <> blnConnected Then
blnConnected = blnSucceed
OnStatusChanged(blnConnected)
End If
OnIdle()
Return blnSucceed
End Function
Public Function Connect() As Boolean
Dim blnSucceed As Boolean = False
Dim optionstr As String = "-f " & file & " -d "
OnConnect()
'MessageBox.Show("strVPNCon = " )
'Process.Start(strRASPhone, Convert.ToString(" -f ") & file & Convert.ToString(" -d ") _
' & strVPNCon)
optionstr = ""
Dim wait As Boolean = True
ProcessExec(strRASPhone, optionstr & strVPNCon, wait)
Application.DoEvents()
System.Threading.Thread.Sleep(5000)
Application.DoEvents()
blnSucceed = True
OnIdle()
Return blnSucceed
End Function
Public Function Disconnect() As Boolean
Dim blnSucceed As Boolean = False
Dim optionstr As String = "-h "
OnDisconnect()
optionstr = ""
Dim wait As Boolean = True
ProcessExec(strRASPhone, optionstr & strVPNCon, wait)
Application.DoEvents()
System.Threading.Thread.Sleep(8000)
Application.DoEvents()
blnSucceed = True
OnIdle()
Return blnSucceed
End Function
Public Function CheckConnection() As Boolean
Dim niVPN As NetworkInterface() =
NetworkInterface.GetAllNetworkInterfaces
Dim blnExist As Boolean =
niVPN.AsEnumerable().Any(Function(x) x.Name = ConName)
If blnExist Then
'MessageBox.Show("VPN Exists")
Else
' MessageBox.Show("VPN Does Not Exist")
End If
Return blnExist
End Function
Public Sub ProcessExec(processarg As String, param As String, wait As Boolean)
' Start the child process.
Dim p As New ProcessStartInfo
' Redirect the output stream of the child process.
p.FileName = processarg
p.Arguments = param
p.UseShellExecute = True
p.WindowStyle = ProcessWindowStyle.Normal
Dim proc As Process = Process.Start(p)
' Do Not wait for the child process to exit before
' reading to the end of its redirected stream.
If wait = True Then
proc.WaitForExit()
End If
End Sub
End Class

Answer 1

I know this was asked more than one year before.
I suppose that the described problem is not caused of the Visual Basic code. The problem may be caused from the file rasphone.pbk. It is generally contained in
%APPDATA%\Microsoft\Network\Connections\Pbk
This file can be read with a text editor. There exist an option PreviewUserPw after [YOURVPNNAME]. The value 1 generates a prompting before dialing in.
Changing of this line to
PreviewUserPw=0
will help.