C#自动换ip功能或者ip代理功能要这么实现

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class Program{[DllImport(@"wininet", SetLastError = true, CharSet = CharSet.Auto,EntryPoint = "InternetSetOption",CallingConvention = CallingConvention.StdCall)]public static extern bool InternetSetOption(int hInternet, int dmOption, IntPtr lpBuffer, int dwBufferLength);public static void SetProxy(string proxy){//打开注册表RegistryKey regKey = Registry.CurrentUser;string SubKeyPath = @"Software\Microsoft\Windows\CurrentVersion\Internet Settings"; RegistryKey optionKey = regKey.OpenSubKey(SubKeyPath, true);             //更改健值，设置代理，optionKey.SetValue("ProxyEnable", 1);optionKey.SetValue("ProxyServer", proxy);//激活代理设置【用于即使IE没有关闭也能更新当前打开的IE中的代理设置。】InternetSetOption(0, 39, IntPtr.Zero, 0);InternetSetOption(0, 37, IntPtr.Zero, 0);}static void Main(string[] args){//本事例中未对代理服务器设置密码的情况进行尝试String ip = null;for (int i = 1; i < 254; i++){ip = "172.0.0." + i + ":808";//ip请替换为你需要查找的ip段SetProxy(ip);if (prcessBaidu()){Console.WriteLine(ip + "_____________TestOK"); break;}else{Console.WriteLine(ip + "__false");}}}//成功返回true，错误返回falsepublic static Boolean prcessBaidu(){HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create("http://www.163.com"); myRequest.Method = "POST"; //采用post方式提交访问163主页 // Get responsetry//当无法访问163网站时，下面的对象会有错误产生，所以用try..catch处理掉这些异常{Stream newStream = myRequest.GetRequestStream();//获取请求流     // Send the data.newStream.Close();//关闭请求流HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();//获取应答对象StreamReader reader = new StreamReader(myResponse.GetResponseStream());//获取应答流string content = reader.ReadToEnd();//将流对象读取到string 中if (content.IndexOf("http://reg.163.com") > -1)//如果访问网站成功，则网页中包含置顶的关键字符串“http://reg.163.com”表示访问网页成功{return true;}else{return false;}}catch (Exception ex){}return false;}}