Vb NET 基礎連接已關閉: 無法為 SSL TLS 安全通道建立信任關係

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	//參考來源1：//blog.darkthread.net/post-2010-05-06-webclient-ssl-dismatch.aspx
	//參考來源2：//awei791129.pixnet.net/blog/post/24463385-%5Bc%23%5D-%E7%95%B6%E8%A6%81%E6%B1%82https%E9%80%A3%E7%B7%9A%E5%87%BA%E7%8F%BE%EF%BC%8C%E5%9F%BA%E7%A4%8E%E9%80%A3%E6%8E%A5%E5%B7%B2%E9%97%9C%E9%96%89%3A-%E7%84%A1
	關鍵參教
	xxx.ServerCertificateValidationCallback = delegate { return true; };
	// 狀況一：改連線設定-範例
	System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
	// 狀況一：使用HttpWebRequest的解法-範例
	HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
	// Set some reasonable limits on resources used by this request
	request.MaximumAutomaticRedirections = 4;
	request.MaximumResponseHeadersLength = 4;
	request.Timeout = (int)numTimeOut.Value; // milliseconds
	// Set credentials to use for this request.
	request.Credentials = CredentialCache.DefaultCredentials;
	request.AuthenticationLevel = (AuthenticationLevel)cbxAuthLevel.SelectedValue; // AuthenticationLevel.None;
	// 排除此Exception觸發：基礎連接已關閉: 無法為 SSL/TLS 安全通道建立信任關係。
	// The underlying connection was closed: Could not establish trust relationship for SSL/TLS secure channel
	request.ServerCertificateValidationCallback = delegate { return true; };
	HttpWebResponse response = (HttpWebResponse)request.GetResponse();
	// 狀況三：使用WebClient的解法-範例
	WebClient wc = new WebClient();
	ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
	string s = wc.DownloadString("//192.168.1.1/Page.aspx");

公司將一些網站改走SSL後發現有些POST取資料功能失效了
出現基礎連接已關閉: 無法為 SSL/TLS 安全通道建立信任關係
解法辦法

ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;<=加入 ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;<=加入

參考來源
[faq]解決C#呼叫有ssl憑證問題的網站出現遠端憑證是無效的錯誤問題
C# HttpReques 基礎連接已關閉: 無法為 SSL/TLS 安全通道建立信任關係 強制跳過 TLS驗證
C# 連線 HTTPS 網站發生驗證失敗導致基礎連接已關閉

2019-07-07

C# HttpReques 基礎連接已關閉: 無法為 SSL/TLS 安全通道建立信任關係 強制跳過 TLS驗證

• 7894
• 0
• C#
• 2019-10-16

如提

C#  HttpReques 基礎連接已關閉: 無法為 SSL/TLS 安全通道建立信任關係    強制跳過 TLS驗證

參考來源

//www.coco-in.net/thread-150342-1-1.html

//blog.alantsai.net/posts/2017/12/csharp-ssl-remote-validation-error

可能會遇到這個畫面

實際寫法

    ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

   HttpWebRequest request = HttpWebRequest.Create(targetUrl) as HttpWebRequest;
                request.Method = "GET";
            request.ContentType = "application/x-www-form-urlencoded";

            string jsondata = "";
            // 取得回應資料
            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
            {
                using (StreamReader sr = new StreamReader(response.GetResponseStream()))
                {
                    jsondata = sr.ReadToEnd();
                }
            }

就可以解決了

以上文章僅用紀錄資料使用.....