Pop up message to remote computer

Question

Hello,
I am trying to send a pop up notification (message) to a remote computer using some proposed methods using the command prompt always unsuccessfully. Could you please help with a Visual Basic program to do this.

Thanks a lot.

Answer 1

Maybe you can test with WTS APIs
I'm not on a network, so I cannot test with a remote computer
Change the server name or use WTS_CURRENT_SERVER_HANDLE :

        Dim pSessions As IntPtr = IntPtr.Zero
        Dim nSessions As Integer
        Dim pServer = WTSOpenServer("Server_Name")
        '  If WTSEnumerateSessions(CType(WTS_CURRENT_SERVER_HANDLE, IntPtr), 0, 1, pSessions, nSessions) Then
        If WTSEnumerateSessions(pServer, 0, 1, pSessions, nSessions) Then
            Dim nDataSize As Integer = Marshal.SizeOf(GetType(WTS_SESSION_INFO))
            Dim pCurrentSession As IntPtr = pSessions
            For Index As Integer = 0 To nSessions - 1
                Dim si As WTS_SESSION_INFO = CType(Marshal.PtrToStructure(pCurrentSession, GetType(WTS_SESSION_INFO)), WTS_SESSION_INFO)
                Dim nResponse As Integer = 0
                Dim sMessageTitle As String = "Title"
                Dim sMessageText As String = "Message"
                Dim nTitleLength As Integer = sMessageTitle.Length * 4
                Dim nMessageLength As Integer = sMessageText.Length * 4
                If si.State = WTS_CONNECTSTATE_CLASS.WTSActive Then
                    'Dim bMessageReturn As Boolean = WTSSendMessage(CType(WTS_CURRENT_SERVER_HANDLE, IntPtr), si.SessionId, sMessageTitle, nTitleLength, sMessageText, nMessageLength, CInt((CInt(MessageBoxButtons.OK) Or CInt(MessageBoxIcon.Exclamation))), 0, nResponse, False)
                    Dim bMessageReturn As Boolean = WTSSendMessage(pServer, si.SessionId, sMessageTitle, nTitleLength, sMessageText, nMessageLength, CInt((CInt(MessageBoxButtons.OK) Or CInt(MessageBoxIcon.Exclamation))), 0, nResponse, False)
                    If Not bMessageReturn Then
                        Dim nError As Integer = Marshal.GetLastWin32Error()
                        System.Windows.Forms.MessageBox.Show("Error : " & nError.ToString(), "Error", MessageBoxButtons.OK, MessageBoxIcon.[Error])
                    End If
                End If
                pCurrentSession += nDataSize
            Next
            WTSFreeMemory(pSessions)
            WTSCloseServer(pServer)
        End If

Declarations :

    Public Const INVALID_HANDLE_VALUE As Integer = -1
    Public Const WTS_CURRENT_SERVER_HANDLE As Integer = 0
    Public Const WTS_CURRENT_SESSION As Integer = -1

    <DllImport("WTSApi32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)>
    Public Shared Function WTSSendMessage(hServer As IntPtr, SessionId As Integer, pTitle As String, TitleLength As Integer, pMessage As String, MessageLength As Integer, Style As Integer, Timeout As Integer, <Out> ByRef pResponse As Integer, bWait As Boolean) As Boolean
    End Function

    <DllImport("WTSApi32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)>
    Public Shared Function WTSEnumerateSessions(hServer As IntPtr, Reserved As Integer, Version As Integer, <Out> ByRef ppSessionInfo As IntPtr, <Out> ByRef pCount As Integer) As Boolean
    End Function

    <DllImport("WTSApi32.dll", SetLastError:=True, CharSet:=CharSet.Auto)>
    Public Shared Sub WTSFreeMemory(pMemory As IntPtr)
    End Sub

    <DllImport("WTSApi32.dll", SetLastError:=True, CharSet:=CharSet.Auto)>
    Public Shared Function WTSOpenServer(pServerName As String) As IntPtr
    End Function

    <DllImport("WTSApi32.dll", SetLastError:=True, CharSet:=CharSet.Auto)>
    Public Shared Sub WTSCloseServer(hServer As IntPtr)
    End Sub

    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)>
    Public Structure WTS_SESSION_INFO
        Public SessionId As Integer
        Public pWinStationName As String
        Public State As WTS_CONNECTSTATE_CLASS
    End Structure

    Public Enum WTS_CONNECTSTATE_CLASS
        WTSActive
        WTSConnected
        WTSConnectQuery
        WTSShadow
        WTSDisconnected
        WTSIdle
        WTSListen
        WTSReset
        WTSDown
        WTSInit
    End Enum

Answer 2

What command did you try? The next example seems to work:

Process.Start("msg", "* /server:Computer123 Hello!")

Replace "Computer123" with the right name of the target computer or server.