Cuando windows establece una conexión modifica un valor en el registro. Este código muestra cómo determinar si el ordenador está conectado o no.

Pondremos las siguientes declaraciones en un módulo :

Public Const ERROR_SUCCESS = 0&
Public Const APINULL = 0&
Public Const HKEY_LOCAL_MACHINE = &H80000002
Public ReturnCode As Long

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

Declare Function RegOpenKey Lib "advapi32.dll" Alias _
"RegOpenKeyA" (ByVal hKey As Long, ByVal lpSubKey As _
String, phkResult As Long) As Long

Declare Function RegQueryValueEx Lib "advapi32.dll" Alias _
"RegQueryValueExA" (ByVal hKey As Long, ByVal lpValueName _
As String, ByVal lpReserved As Long, lpType As Long, _
lpData As Any, lpcbData As Long) As Long

Y la siguiente función devolverá true si existe una conexión activa :

Public Function ActiveConnection() As Boolean
Dim hKey As Long
Dim lpSubKey As String
Dim phkResult As Long
Dim lpValueName As String
Dim lpReserved As Long
Dim lpType As Long
Dim lpData As Long
Dim lpcbData As Long
ActiveConnection = False
lpSubKey = "System\CurrentControlSet\Services\RemoteAccess"
ReturnCode = RegOpenKey(HKEY_LOCAL_MACHINE, lpSubKey, _
phkResult)

If ReturnCode = ERROR_SUCCESS Then
    hKey = phkResult
    lpValueName = "Remote Connection"
    lpReserved = APINULL
    lpType = APINULL
    lpData = APINULL
    lpcbData = APINULL
    ReturnCode = RegQueryValueEx(hKey, lpValueName, _
    lpReserved, lpType, ByVal lpData, lpcbData)
    lpcbData = Len(lpData)
    ReturnCode = RegQueryValueEx(hKey, lpValueName, _
    lpReserved, lpType, lpData, lpcbData)

    If ReturnCode = ERROR_SUCCESS Then
        If lpData = 0 Then
            ActiveConnection = False
        Else
            ActiveConnection = True
        End If
    End If


RegCloseKey (hKey)
End If

End Function