C# IE代理操作

 public class IPProxy
     {
         [System.Runtime.InteropServices.DllImport("wininet.dll", SetLastError = true)]
         private static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lPBuffer, int lpdwBufferLength);
         private const int INTERNET_OPTION_REFRESH = 0x000025;
         private const int INTERNET_OPTION_SETTINGS_CHANGED = 0x000027;

         public static bool Proxy(string ip,int port) {
             Microsoft.Win32.RegistryKey rk = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Internet Settings", true);
             //设置代理可用
             rk.SetValue("ProxyEnable", );
             //设置代理IP和端口
             rk.SetValue("ProxyServer", string.Format("{0}:{1}", ip, port));
             rk.Close();
             //使它立即生效
             InternetSetOption(IntPtr.Zero, INTERNET_OPTION_SETTINGS_CHANGED, IntPtr.Zero, );
             InternetSetOption(IntPtr.Zero, INTERNET_OPTION_REFRESH, IntPtr.Zero, );
             if (IsUseful("http://www.baidu.com/")) {
                 return true;
             }
             CancelProxy();
             return false;
         }
         public static void CancelProxy() {
             Microsoft.Win32.RegistryKey rk = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(@"Software\Microsoft\Windows\CurrentVersion\Internet Settings", true);
             rk.SetValue("ProxyEnable", );
         }
         public static bool IsUseful(string ipOrHost) {
             using (System.Net.NetworkInformation.Ping pingSender = new System.Net.NetworkInformation.Ping())
             {

                 try
                 {

                     return System.Net.NetworkInformation.IPStatus.Success.Equals(pingSender.Send(ipOrHost,).Status);
                 }
                 catch {
                     return false;
                 }
             }

         }
     }