无法使用WebClient.DownloadFile方法从启用了TLS 1.1 / 1.2协议的计算机下载文件 [英] Can't download files from the computer with enabled TLS 1.1/1.2 protocols using WebClient.DownloadFile method

问题描述

我正在尝试使用Webclient.DownloadFile方法通过TLS 1.1 / 1.2协议实现一个简单的控制台应用程序来下载文件。
这是应用程序的代码：

I'm trying to implement a simple console application to download the files using Webclient.DownloadFile method over TLS 1.1/1.2 protocols. This is the code for the application:

var downloadUrl = "https://serverURL.com/sample.mp3";
var filename = "sample.mp3";
var myWebClient = new WebClient();
myWebClient.DownloadFile(downloadUrl, filename);

我每次运行它时都会收到以下错误消息：

Everytime I run it I'm getting the following error message:

Unhandled Exception: System.Net.WebException: 
The underlying connection was closed: An unexpected error occurred on a receive. --->   

System.ComponentModel.Win32Exception: The client and server cannot communicate, because they do not possessa common algorithm
at System.Net.SSPIWrapper.AcquireCredentialsHandle(SSPIInterface SecModule, String package, CredentialUse intent, SecureCredential scc)
at System.Net.Security.SecureChannel.AcquireCredentialsHandle(CredentialUse credUsage, SecureCredential& secureCredential)
at System.Net.Security.SecureChannel.AcquireClientCredentials(Byte[]& thumbPrint)
at System.Net.Security.SecureChannel.GenerateToken(Byte[] input, Int32 offset, Int32 count, Byte[]& output)
at System.Net.Security.SecureChannel.NextMessage(Byte[] incoming, Int32 offset, Int32 count)
at System.Net.Security.SslState.StartSendBlob(Byte[] incoming, Int32 count, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
at System.Net.TlsStream.CallProcessAuthentication(Object state)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.ConnectStream.WriteHeaders(Boolean async)
--- End of inner exception stack trace ---
at System.Net.WebClient.DownloadFile(Uri address, String fileName)
at System.Net.WebClient.DownloadFile(String address, String fileName)
at web_downloader.Program.Main(String[] args) in c:\Users\user\Documents\Visual Studio 2013\Projects\web_downloader\web_downloader\Program.cs:line 27

我有以下设置：web_downloader应用程序位于 ServerA （Windows Server 2012 R2 / 64bit），在 HKEY_LOCAL_MACHINE / SYSTEM / CurrentControlSet / Control / SecurityProviders / SCHANNEL / Protocols 下的注册表项中包含以下内容：

I have the following setup: web_downloader application is located on ServerA (Windows Server 2012 R2/64bit), which has the following in the registry key under HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/SecurityProviders/SCHANNEL/Protocols:

PCT 1.0
--Client
----DisabledByDefault=1
----Enabled=0
--Server
----DisabledByDefault=1
----Enabled=0
SSL 2.0
--Client
----DisabledByDefault=1
----Enabled=0
--Server
----DisabledByDefault=1
----Enabled=0
SSL 3.0
--Client
----DisabledByDefault=1
----Enabled=0
--Server
----DisabledByDefault=1
----Enabled=0
TLS 1.0
--Client
----DisabledByDefault=1
----Enabled=0
--Server
----DisabledByDefault=1
----Enabled=0
TLS 1.1
--Client
----DisabledByDefault=0
----Enabled=1
--Server
----DisabledByDefault=0
----Enabled=1
TLS 1.2
--Client
----DisabledByDefault=0
----Enabled=1
--Server
----DisabledByDefault=0
----Enabled=1

存储 sample.mp3 文件的 ServerB 具有以下内容：

And ServerB, which stores sample.mp3 file, has the following:

SSL 2.0
  Client
    DisabledByDefault=1
TLS 1.1
  Client
    DisabledByDefault=0
    Enabled=1
  Server
    DisabledByDefault=0
    Enabled=1
TLS 1.2
  Client
    DisabledByDefault=0
    Enabled=1
  Server
    DisabledByDefault=0
    Enabled=1

我在 ServerA <上启用TLS 1.0 / strong>我可以从 ServerB （Windows 7/64位/ Net Framework 4.5.1）没有任何问题。

As soon as I enable TLS 1.0 on ServerA I'm able to download the mp3 file from ServerB (Windows 7/64bit/Net Framework 4.5.1) without any issues.

系统加密：使用符合FIPS标准的算法进行加密，两台计算机上都禁用了哈希和签名策略。

我是否缺少DownloadFile方法的任何配置参数以使用TLS 1.1 / 1.2？

Am I missing any configuration parameters for DownloadFile method to work with TLS 1.1/1.2?

推荐答案

.NET Framework使用自己的设置来确定默认使用的HTTPS版本。有关 ServicePointManager.SecurityProtocol <的信息，请参见 https://stackoverflow.com/a/169396/126229 / code>设置在客户端上设置以确保它尝试协商TLS1.1连接。

The .NET Framework uses its own settings to decide which HTTPS versions to use by default. See https://stackoverflow.com/a/169396/126229 for the ServicePointManager.SecurityProtocol setting to set on the client to ensure that it attempts to negotiate a TLS1.1 connection.

您还可以使用Fiddler观察出站流量（查看 CONNECT 隧道的TextView请求检查器）以获取ClientHello消息的细分。请注意，启用HTTPS解密的运行Fiddler会产生干扰，因为Fiddler本身默认使用SSL3 + TLS1与服务器通信。

You can also watch the outbound traffic with Fiddler (look at the CONNECT Tunnel's TextView Request inspector) for a breakdown of the ClientHello message. Be warned that running Fiddler with HTTPS-decryption enabled will interfere because Fiddler itself defaults to using SSL3+TLS1 to talk to servers.

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