检测代理IP是否可用

curl -x http://proxyserver.example.com:8080 http://example.com

C#检测代理IP是否可用

var proxyObject = new WebProxy("这里填写IP地址", port);// port为端口号 整数型
var Req =WebRequest.Create("这里写需要访问的网页")as HttpWebRequest;
Req.Proxy = proxyObject; //设置代理
Req.Timeout = 5000;   //超时
var Resp = (HttpWebResponse)Req.GetResponse();
var bin = Encoding.GetEncoding("UTF-8");
var sr = new StreamReader(Resp.GetResponseStream(), bin);
var str = sr.ReadToEnd();
if (str.Contains("这里写网页的关键字"))
{
     result = true;
     sr.Close();
     sr.Dispose();
}