C# 验证过滤代理IP是否有效

private bool VerIP(string ip,int port)
        {
            try
            {
                HttpWebRequest Req;
                HttpWebResponse Resp;
                WebProxy proxyObject = new WebProxy(ip, port);// port为端口号 整数型
                Req = WebRequest.Create("https://www.baidu.com") as HttpWebRequest;
                Req.Proxy = proxyObject; //设置代理
                Req.Timeout = 1000;   //超时
                Resp = (HttpWebResponse)Req.GetResponse();
                Encoding bin = Encoding.GetEncoding("UTF-8");
                using (StreamReader sr = new StreamReader(Resp.GetResponseStream(), bin))
                {
                    string str = sr.ReadToEnd();
                    if (str.Contains("百度"))
                    {
                        Resp.Close();
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                
            }
            catch (Exception ex)
            {
                return false;
            }
        }

C# 验证过滤代理IP是否有效