How to clear TCP/IP Gateway using WMI in Vista/Server 2008?

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Hi,

Now I'm writing this, I've read about 30 pages over internet and found nothing acceptable.

I have written a code using WMI(Win32_NetworkAdapterConfigurationonfiguration) in VB.Net which sets and clears Gateway/DNS for a specific IPEnabled network adapter.
This code works great on Windows XP/2003 Server, but in Vista/Server 2008 it cannot CLEAR the gateway anyway.
I tried to pass a Null array to SetGatways method, but nothing happened
tried to pass a Null array for GatewayCostMetrics, unsuccessful.
I also tried wbemtest.exe to execute the method directly, but that one doesn't help too.

I don't know if this is a bug or not, but every article I read from microsoft support, ended with no result.

Here I will write 2 VBScript code blocks,
first will write a Gateway/DNS to the preferred IPEnabled NIC and second will attempt to clear those.

I appreciate any help on this issue.

Gateway/DNS Set code:

VBScript

strComputer = "."
arrDefaultGateways = Array("192.168.0.1")
arrGatewayCostMetrics = Array(1) ' uint16
arrDNSServers = Array("192.168.0.1")
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colNicConfigs = objWMIService.ExecQuery _
    ("SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = True")
For Each objNicConfig In colNicConfigs
    If objNicConfig.IPEnabled Then
        strText = objNicConfig.Description & vbNewLine _
            & objNicConfig.MACAddress & vbNewLine & vbNewLine _
            & "Do you want to change Gateway/DNS of this NIC?"
        strTitle = "Question..."
        intMsg = MsgBox(strText,vbYesNo,strTitle)
        Select Case intMsg
            Case 6 'yes
                intGWReturn = objNicConfig.SetGateways(arrDefaultGateways, _
                    arrGatewayCostMetrics)
                intDNSReturn = objNicConfig.SetDNSServerSearchOrder(arrDNSServers)
                If (intGWReturn + intDNSReturn = 0) Then
                    WScript.Echo "Successful"
                Else
                    WScript.Echo "Gateway Return code= "  & intGWReturn _
                        & vbNewLine & "DNS Return code= " & intDNSReturn
                End If
                Exit For
            Case 7 'no
        End Select
    End If
Next

Gateway/DNS Clear code:

VBScript

strComputer = "."
arrDefaultGateways = Array() 	' < Empty Array
arrGatewayCostMetrics = Array() ' < Empty Array
arrDNSServers = Array() 		' < Empty Array
Set objWMIService = GetObject("winmgmts:" _
	& "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
Set colNicConfigs = objWMIService.ExecQuery _
	("SELECT * FROM Win32_NetworkAdapterConfiguration WHERE IPEnabled = True")
For Each objNicConfig In colNicConfigs
	If objNicConfig.IPEnabled Then
		strText = objNicConfig.Description & vbNewLine _
			& objNicConfig.MACAddress & vbNewLine & vbNewLine _
			& "Do you want to change Gateway/DNS of this NIC?"
		strTitle = "Question..."
		intMsg = MsgBox(strText,vbYesNo,strTitle)
		Select Case intMsg
			Case 6 'yes
				intGWReturn = objNicConfig.SetGateways(arrDefaultGateways, _
					arrGatewayCostMetrics)
				intDNSReturn = objNicConfig.SetDNSServerSearchOrder(arrDNSServers)
				If (intGWReturn + intDNSReturn = 0) Then
					WScript.Echo "Successful"
				Else
					WScript.Echo "Gateway Return code= "  & intGWReturn _
						& vbNewLine & "DNS Return code= " & intDNSReturn
				End If
				Exit For
			Case 7 'no
		End Select
	End If
Next

Posted 11-Feb-10 22:34pm

Mahyar.FF

Updated 29-Jan-17 11:19am

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sclementi · Answer 1 · 2010-12-14T01:50:00

Hi,
I had the same problem in C#. I did the following:
First I enabled DHCP.Then i copy the List of Geatways into an array.
After that I reset the Geatway manually to the last value of the array(Which is allways the Gateway recived from the DHCP server).
As a last step I enable DHCP again.

Here is my Code in C#:

ManagementClass mc = new ManagementClass("Win32_NetworkAdapterConfiguration");
			ManagementObjectCollection moc = mc.GetInstances();
			foreach(ManagementObject mo in moc)
			{
				// Make sure this is a IP enabled device. Not something like memory card or VM Ware
				if( (bool)mo["IPEnabled"] )
				{
					if( mo["Caption"].Equals( nicName ) )
					{
                        //Enable DHCP         
                        ManagementBaseObject newDNS = mo.GetMethodParameters( "SetDNSServerSearchOrder" );
						newDNS[ "DNSServerSearchOrder" ] = null;
						ManagementBaseObject enableDHCP = mo.InvokeMethod( "EnableDHCP", null, null);
						ManagementBaseObject setDNS = mo.InvokeMethod( "SetDNSServerSearchOrder", newDNS, null);
                        //Save all Gateways into an array
                        string[] gateways = (string[])mo["DefaultIPGateway"];
                       
                        ManagementBaseObject newIP = mo.GetMethodParameters("EnableStatic");                 
                        ManagementBaseObject newGate = mo.GetMethodParameters("SetGateways");
                                               
                        //Set last value of the array(always the Gateway recived by DHCP) as the default Gateway
                        newGate["DefaultIPGateway"] = new string[] {gateways[gateways.Length-1]};                   
                        newGate["GatewayCostMetric"] = new int[] { 1 };
                        //Set IP settings back to static
                        ManagementBaseObject setIP = mo.InvokeMethod("EnableStatic", newIP, null);
                        ManagementBaseObject setGateways = mo.InvokeMethod("SetGateways", newGate, null);
                        //Enable DHCP  again
                        newDNS["DNSServerSearchOrder"] = null;
                        ManagementBaseObject enableDHCP2 = mo.InvokeMethod("EnableDHCP", null, null);
                        ManagementBaseObject setDNS2 = mo.InvokeMethod("SetDNSServerSearchOrder", newDNS, null);
					}
				}
			}

Maybe not the most elegant way to do it, but it works

BornToBeRoot · Answer 2 · 2017-01-29T11:19:00

Based on the other solution, but this will ignore IPv6 and without DNS...

1) Enable DHCP
2) RenewDHCPLease
3) FixGateway()

C#

public static void FixGateway(string networkInterfaceId)
        {
            foreach (ManagementObject adapter in new ManagementClass("Win32_NetworkAdapterConfiguration").GetInstances())
            {
                if (adapter["SettingID"] as string == networkInterfaceId)
                {
                    string[] gateways = (string[])adapter["DefaultIPGateway"];

                    string gateway = string.Empty;

                    foreach (string gw in gateways)
                    {
                        if (IPAddress.Parse(gw).AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)
                            gateway = gw;
                    }

                    ManagementBaseObject newIP = adapter.GetMethodParameters("EnableStatic");

                    adapter.InvokeMethod("EnableStatic", newIP, null);

                    ManagementBaseObject newGateway = adapter.GetMethodParameters("SetGateways");

                    newGateway["DefaultIPGateway"] = new string[] { gateway };
                    newGateway["GatewayCostMetric"] = new int[] { 1 };
                    
                    adapter.InvokeMethod("SetGateways", newGateway, null);

                    adapter.InvokeMethod("EnableDHCP", null, null);
                }
            }
        }

How to clear TCP/IP Gateway using WMI in Vista/Server 2008?

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