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SendKeys not working

Posted on 2009-07-01
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1,804 Views
Last Modified: 2012-05-07
Hi all,
I am using the following script to reboot my DSL router. It is working perfectly fine when a user account is signed in. But when the computer is locked(Windows + L key) the script fails. I have investigated and found that SendKeys will not work when the computer is locked. So what are my options? What should I use instead of "Sendkeys"?
Note: This script is run from a VB.NET application whenever internet stays disconnected for more than 2 minutes....
Can the script be eliminated and done form inside the VB.NET code?
OS: Windows XP SP3
VB.NET 2008
On Error Resume Next
strComputer = "."
 
Dim  WshShell, Windir, i, objWMIService,SeverName
 
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
 
Set WshShell = CreateObject("WScript.Shell")
WinDir = WshShell.ExpandEnvironmentStrings("%WinDir%")
ServerName = " 192.168.1.1"
 
 
        'Launch telnet session from the command line
        WshShell.Run "telnet " & ServerName
        'Wait until the application has loaded
        WScript.Sleep 300    
        Set ColProcesses = objWMIService.ExecQuery("Select * from Win32_Process",,48)
        For Each Process in ColProcesses
           If Process.Name = "telnet.exe"  Then
              WshShell.AppActivate Process.Name
           End If
        Next
            wscript.sleep 100
            WshShell.SendKeys "root"
            wscript.sleep 200
            WshShell.SendKeys "{ENTER}"
            wscript.sleep 200
            WshShell.SendKeys "admin"
            wscript.sleep 200
            WshShell.SendKeys "{ENTER}"
            wscript.sleep 200
            WshShell.SendKeys "reboot"
            wscript.sleep 200
            WshShell.SendKeys "{ENTER}"
            wscript.sleep 200
Set ColProcesses = objWMIService.ExecQuery("Select * from Win32_Process",,48)
        For Each Process in ColProcesses
           If Process.Name = "telnet.exe" Then
              Process.Terminate()
           End If
        Next

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Question by:imarshad
5 Comments
 
LVL 13

Expert Comment

by:kaylanreilor
ID: 24753761
SendKeys is used to send the message that a keyboard's key has been pressed to a window. So, of course, somebody must be logged on the machine.
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LVL 85

Accepted Solution

by:
Mike Tomlinson earned 500 total points
ID: 24755653
"Can the script be eliminated and done form inside the VB.NET code?"

Unproven code...I tested by sending simple commands like "help" and "display" while the computer was NOT locked:
(just FYI...I have zero experience using telnet)
Public Class Form1
 
    Private Const WM_CHAR As Integer = &H102
 
    Private Declare Function PostMessage Lib "user32" Alias "PostMessageA" ( _
        ByVal hwnd As Integer, ByVal wMsg As Integer, _
        ByVal wParam As Integer, ByVal lParam As Integer) As Integer
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim ServerName As String = "192.168.1.1"
        Dim script() As String = {"root", "admin", "reboot"}
        Dim telnet As Process = Process.Start("telnet", ServerName)
        System.Threading.Thread.Sleep(2000) ' delay to make sure it's loaded
 
        Dim c As String
        For Each cmd As String In script
            For i As Integer = 0 To cmd.Length - 1
                c = cmd.Substring(i, 1)
                PostMessage(telnet.MainWindowHandle, WM_CHAR, Asc(c), 0&)
            Next i
            PostMessage(telnet.MainWindowHandle, WM_CHAR, Asc(vbCr), 0&)
            PostMessage(telnet.MainWindowHandle, WM_CHAR, Asc(vbLf), 0&)
            System.Threading.Thread.Sleep(200)
        Next
 
        telnet.CloseMainWindow()
    End Sub
 
End Class

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LVL 85

Expert Comment

by:Mike Tomlinson
ID: 24755816
I just did another simple test and was able to open a telnet window and send several commands while the computer was LOCKED.  =)
0
 
LVL 83

Expert Comment

by:CodeCruiser
ID: 24761627
0
 
LVL 13

Author Comment

by:imarshad
ID: 24766606
Thanks Idle_mind..... This was exactly what I was looking for....
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