public class IEProxySetting

    {

        public static bool UnsetProxy()

        {

            return SetProxy(null, null);

        }

        public static bool SetProxy(string strProxy)

        {

            return SetProxy(strProxy, null);

        }

        public static bool SetProxy(string strProxy, string exceptions)

        {

            InternetPerConnOptionList list = new InternetPerConnOptionList();

            int optionCount = string.IsNullOrEmpty(strProxy) ?  : (string.IsNullOrEmpty(exceptions) ?  : );

            InternetConnectionOption[] options = new InternetConnectionOption[optionCount];

            // USE a proxy server ...

            options[].m_Option = PerConnOption.INTERNET_PER_CONN_FLAGS;

            options[].m_Value.m_Int = (int)((optionCount < ) ? PerConnFlags.PROXY_TYPE_DIRECT : (PerConnFlags.PROXY_TYPE_DIRECT | PerConnFlags.PROXY_TYPE_PROXY));

            // use THIS proxy server

            if (optionCount > )

            {

                options[].m_Option = PerConnOption.INTERNET_PER_CONN_PROXY_SERVER;

                options[].m_Value.m_StringPtr = Marshal.StringToHGlobalAuto(strProxy);

                // except for these addresses ...

                if (optionCount > )

                {

                    options[].m_Option = PerConnOption.INTERNET_PER_CONN_PROXY_BYPASS;

                    options[].m_Value.m_StringPtr = Marshal.StringToHGlobalAuto(exceptions);

                }

            }

            // default stuff

            list.dwSize = Marshal.SizeOf(list);

            list.szConnection = IntPtr.Zero;

            list.dwOptionCount = options.Length;

            list.dwOptionError = ;

            int optSize = Marshal.SizeOf(typeof(InternetConnectionOption));

            // make a pointer out of all that ...

            IntPtr optionsPtr = Marshal.AllocCoTaskMem(optSize * options.Length);

            // copy the array over into that spot in memory ...

            for (int i = ; i < options.Length; ++i)

            {

                IntPtr opt = new IntPtr(optionsPtr.ToInt32() + (i * optSize));

                Marshal.StructureToPtr(options[i], opt, false);

            }

            list.options = optionsPtr;

            // and then make a pointer out of the whole list

            IntPtr ipcoListPtr = Marshal.AllocCoTaskMem((Int32)list.dwSize);

            Marshal.StructureToPtr(list, ipcoListPtr, false);

            // and finally, call the API method!

            int returnvalue = NativeMethods.InternetSetOption(IntPtr.Zero,

               InternetOption.INTERNET_OPTION_PER_CONNECTION_OPTION,

               ipcoListPtr, list.dwSize) ? - : ;

            if (returnvalue == )

            {  // get the error codes, they might be helpful

                returnvalue = Marshal.GetLastWin32Error();

            }

            // FREE the data ASAP

            Marshal.FreeCoTaskMem(optionsPtr);

            Marshal.FreeCoTaskMem(ipcoListPtr);

            if (returnvalue > )

            {  // throw the error codes, they might be helpful

                throw new Win32Exception(Marshal.GetLastWin32Error());

            }

            return (returnvalue < );

        }

        /// <summary>

        /// 获取正在使用的代理

        /// </summary>

        /// <returns></returns>

        public static string GetProxyServer()

        {

            //打开注册表

            RegistryKey regKey = Registry.CurrentUser;

            string SubKeyPath = "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings";

            //更改健值，设置代理

            RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);

            //是否启用 1 启用

            int actualProxyStatus = Convert.ToInt32(optionKey.GetValue("ProxyEnable"));

            string actualProxy = string.Empty;

            if (actualProxyStatus == )

            {

                actualProxy = optionKey.GetValue("ProxyServer").ToString();

            }

            regKey.Close();

            return actualProxy;

        }

    }

    #region WinInet structures

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

    public struct InternetPerConnOptionList

    {

        public int dwSize;               // size of the INTERNET_PER_CONN_OPTION_LIST struct

        public IntPtr szConnection;         // connection name to set/query options

        public int dwOptionCount;        // number of options to set/query

        public int dwOptionError;           // on error, which option failed

        //[MarshalAs(UnmanagedType.)]

        public IntPtr options;

    };

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]

    public struct InternetConnectionOption

    {

        static readonly int Size;

        public PerConnOption m_Option;

        public InternetConnectionOptionValue m_Value;

        static InternetConnectionOption()

        {

            InternetConnectionOption.Size = Marshal.SizeOf(typeof(InternetConnectionOption));

        }

        // Nested Types

        [StructLayout(LayoutKind.Explicit)]

        public struct InternetConnectionOptionValue

        {

            // Fields

            [FieldOffset()]

            public System.Runtime.InteropServices.ComTypes.FILETIME m_FileTime;

            [FieldOffset()]

            public int m_Int;

            [FieldOffset()]

            public IntPtr m_StringPtr;

        }

    }

    #endregion

    #region WinInet enums

    //

    // options manifests for Internet{Query|Set}Option

    //

    public enum InternetOption : uint

    {

        INTERNET_OPTION_PER_CONNECTION_OPTION =

    }

    //

    // Options used in INTERNET_PER_CONN_OPTON struct

    //

    public enum PerConnOption

    {

        INTERNET_PER_CONN_FLAGS = , // Sets or retrieves the connection type. The Value member will contain one or more of the values from PerConnFlags

        INTERNET_PER_CONN_PROXY_SERVER = , // Sets or retrieves a string containing the proxy servers.

        INTERNET_PER_CONN_PROXY_BYPASS = , // Sets or retrieves a string containing the URLs that do not use the proxy server.

        INTERNET_PER_CONN_AUTOCONFIG_URL = //, // Sets or retrieves a string containing the URL to the automatic configuration script.  

    }

    //

    // PER_CONN_FLAGS

    //

    [Flags]

    public enum PerConnFlags

    {

        PROXY_TYPE_DIRECT = 0x00000001,  // direct to net

        PROXY_TYPE_PROXY = 0x00000002,  // via named proxy

        PROXY_TYPE_AUTO_PROXY_URL = 0x00000004,  // autoproxy URL

        PROXY_TYPE_AUTO_DETECT = 0x00000008   // use autoproxy detection

    }

    #endregion

    internal static class NativeMethods

    {

        [DllImport("WinInet.dll", SetLastError = true, CharSet = CharSet.Auto)]

        [return: MarshalAs(UnmanagedType.Bool)]

        public static extern bool InternetSetOption(IntPtr hInternet, InternetOption dwOption, IntPtr lpBuffer, int dwBufferLength);

    }