C# Signature:

[DllImport("Iphlpapi.dll", CharSet = CharSet.Auto)]
public static extern int GetInterfaceInfo(Byte[] PIfTableBuffer, ref int size);

User-Defined Types:

None.

Alternative Managed API:

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Notes:

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Tips & Tricks:

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Sample Code:

The following C# sourcecode implements classes and structures with the purpose of making the use of GetInterfaceInfo and IpReleaseAddress easier. Thanks to Lieutenant (http://www.red-gate.com/MessageBoard/viewtopic.php?t=5754) for submitting this code.

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct IP_ADAPTER_INDEX_MAP
    {
        public int Index;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = PInvokes.MAX_ADAPTER_NAME)]
        public String Name;
    }

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
    public struct IP_INTERFACE_INFO
    {
        public int NumAdapters;
        public IP_ADAPTER_INDEX_MAP[] Adapter;

        public static IP_INTERFACE_INFO FromByteArray(Byte[] buffer)
        {
        unsafe
        {
            IP_INTERFACE_INFO rv = new IP_INTERFACE_INFO();
            int iNumAdapters = 0;
            Marshal.Copy(buffer, 0, new IntPtr(&iNumAdapters), 4);
            IP_ADAPTER_INDEX_MAP[] adapters = new IP_ADAPTER_INDEX_MAP[iNumAdapters];
            rv.NumAdapters = iNumAdapters;
            rv.Adapter = new IP_ADAPTER_INDEX_MAP[iNumAdapters];
            int offset = sizeof(int);
            for (int i = 0; i < iNumAdapters; i++)
            {
            IP_ADAPTER_INDEX_MAP map = new IP_ADAPTER_INDEX_MAP();
            IntPtr ptr = Marshal.AllocHGlobal(Marshal.SizeOf(map));
            Marshal.StructureToPtr(map, ptr, false);
            Marshal.Copy(buffer, offset, ptr, Marshal.SizeOf(map));
            map = (IP_ADAPTER_INDEX_MAP)Marshal.PtrToStructure(ptr, typeof(IP_ADAPTER_INDEX_MAP));
            Marshal.FreeHGlobal(ptr);
            rv.Adapter[i] = map;
            offset += Marshal.SizeOf(map);
            }
            return rv;
         }
        }
    }

    internal class PInvokes
    {
        public const int MAX_ADAPTER_NAME = 128;

        public const int ERROR_INSUFFICIENT_BUFFER = 122;
        public const int ERROR_SUCCESS = 0;

        [DllImport("Iphlpapi.dll", CharSet = CharSet.Auto)]
        public static extern int GetInterfaceInfo(Byte[] PIfTableBuffer, ref int size);

        [DllImport("Iphlpapi.dll", CharSet = CharSet.Auto)]
        public static extern int IpReleaseAddress(ref IP_ADAPTER_INDEX_MAP AdapterInfo);
    }

    public class Iphlpapi
    {
        public static IP_INTERFACE_INFO GetInterfaceInfo()
        {
        int size = 0;
        int r = PInvokes.GetInterfaceInfo(null, ref size);
        Byte[] buffer = new Byte[size];
        r = PInvokes.GetInterfaceInfo(buffer, ref size);
        if (r != PInvokes.ERROR_SUCCESS)
            throw new Exception("GetInterfaceInfo returned an error.");
        IP_INTERFACE_INFO info = IP_INTERFACE_INFO.FromByteArray(buffer);
        return info;
        }

        public static bool IpReleaseAddress(IP_ADAPTER_INDEX_MAP adapter)
        {
        if (PInvokes.IpReleaseAddress(ref adapter) == PInvokes.ERROR_SUCCESS)
            return true;
        else
            return false;
        }

        public static void IpReleaseAllAddresses()
        {
        IP_INTERFACE_INFO info = GetInterfaceInfo();
        for (int i = 0; i < info.NumAdapters; i++)
            IpReleaseAddress(info.Adapter[i]);
        }
    }

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