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DhcpDeleteClientInfo (dhcpsapi)
.
C# Signature:
[DllImport("dhcpsapi.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern int DhcpDeleteClientInfo(
string DHCPServer,
IntPtr ClientInfo);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct DHCP_SEARCH_INFO
{
public int DHCPSearchInfoType;
public UInt32 DHCPIPAddress;
}
public enum DHCP_SEARCH_INFO_TYPE
{
DhcpClientIpAddress,
DhcpClientHardwareAddress,
DhcpClientName
}
static extern TODO DhcpDeleteClientInfo(TODO);
VB Signature and sample code:
Imports System.Runtime.InteropServices
Module Module3
Private Declare Unicode Function DhcpDeleteClientInfo Lib "dhcpsapi.dll" ( _
ByVal DHCPServer As String, _
ByVal ClientInfo As Integer) As Integer
Private Structure DHCP_SEARCH_INFO
Dim DHCPSearchInfoType As Integer
Dim DHCPIPAddress As UInt32
End Structure
Private Enum DHCP_SEARCH_INFO_TYPE
DhcpClientIpAddress
DhcpClientHardwareAddress
DhcpClientName
End Enum
Private Declare Function NetApiBufferAllocate Lib "NETAPI32.DLL" (ByVal ByteCount As Integer, ByRef Buffer As Integer) As Integer
Private Declare Function NetAPIBufferFree Lib "Netapi32" Alias "NetApiBufferFree" (ByVal lpBuffer As Integer) As Integer
Public Sub DeleteDHCPLease(ByVal IPAddress As String)
Dim Octets() As String = IPAddress.Split(".")
Dim HexIP As String
For Each Octet As String In Octets
HexIP &= Convert.ToString(Convert.ToInt16(Octet), 16).PadLeft(2, "0")
Next
'Dim a As Int32 = Convert.ToInt32(BinaryIP)
Dim bufptr As Integer
Dim StructSize As Integer
Dim ClientInfo As New DHCP_SEARCH_INFO
ClientInfo.DHCPSearchInfoType = DHCP_SEARCH_INFO_TYPE.DhcpClientIpAddress
ClientInfo.DHCPIPAddress = Convert.ToUInt32(HexIP, 16)
Dim result As Integer = DhcpDeleteClientInfo("nn.nn.nn.nn", bufptr)
NetAPIBufferFree(bufptr)
End Sub
End Module!!!!User-Defined Types:
None.
Alternative Managed API:
Do you know one? Please contribute it!
Notes:
C# Code runs daily to delete non ping leases
Tips & Tricks:
You need to manage the structure to avoid 2013 error:
[DllImport("netapi32.dll", SetLastError = true)]
public extern static int NetApiBufferFree(IntPtr lpBuffer);
[DllImport("netapi32.dll", SetLastError = true)]
public extern static int NetApiBufferAllocate(int ByteCount,ref int Buffer);
Sample Code:
[DllImport("dhcpsapi.dll", SetLastError = true, CharSet = CharSet.Unicode)]
public static extern int DhcpDeleteClientInfo(
string DHCPServer,
IntPtr ClientInfo);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct DHCP_SEARCH_INFO
{
public int DHCPSearchInfoType;
public UInt32 DHCPIPAddress;
}
public enum DHCP_SEARCH_INFO_TYPE
{
DhcpClientIpAddress,
DhcpClientHardwareAddress,
DhcpClientName
}
[DllImport("netapi32.dll", SetLastError = true)]
public extern static int NetApiBufferFree(IntPtr lpBuffer);
[DllImport("netapi32.dll", SetLastError = true)]
public extern static int NetApiBufferAllocate(int ByteCount,ref int Buffer);
static extern TODO DhcpDeleteClientInfo(TODO);
static void Main(string[] args)
{
//A utility that looks at the dynamic ranges on the following DHCP scopes and deletes the unused dynamic IP reservations
//(e.g. laptops that have visited the site and have now left before the 5 days lease period). The utility would run during
//the early hours of the morning against the scopes:- 10.13.25.0, 10.13.27.0, 10.13.107.0 and 10.13.109.0 Laptops that were
//left connected overnight should have their IP dynamic lease left untouched.
// Dynamics - 241 to 254
string scope = "";
for (int s = 1; s < 5; s++)
{
switch (s)
{
case 1:
scope = "10.13.25.";
break;
case 2:
scope = "10.13.27.";
break;
case 3:
scope = "10.13.107.";
break;
case 4:
scope = "10.13.109.";
break;
}
for (int i = 241; i < 255; i++)
{
int result = DhcpDeleteClientInfo(dhcpServer, (IntPtr)bufptr);
NetApiBufferFree((IntPtr)bufptr);
}
}
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