证书错误：身份验证失败，因为远程方已关闭传输流

Question

我正在制作代理服务器。我使用Implementing a Multithreaded HTTP/HTTPS Debugging Proxy Server in C#作为参考。

这段代码：

    private void ProccessRequest(Socket client)
    {
        // Create network stream from socket for read and write data
        Stream networkStream = new NetworkStream(client, true);
        // Create stream reader for read data from socket
        StreamReader clientReader = new StreamReader(networkStream);
        // For read and write data to socket
        // Same for http and https requests
        Stream clientStream = networkStream;            

        try
        {
            if (client.Connected)
            {
                // Get first request line
                string str = clientReader.ReadLine();
                if (!String.IsNullOrEmpty(str))
                {
                    string[] tmpStr = str.Split(SapceSplit, 3);

                    String method = tmpStr[0];
                    String remoteUrl = tmpStr[1];

                    if (method.Equals("CONNECT", StringComparison.OrdinalIgnoreCase))
                    {
                        remoteUrl = "https://" + remoteUrl;

                        // Read all information from socket
                        while (!String.IsNullOrEmpty(clientReader.ReadLine())) ;

                        // Tell browser that connection established
                        StreamWriter connectWriter = new StreamWriter(networkStream);
                        connectWriter.WriteLine("HTTP/1.0 200 Connection established");
                        connectWriter.WriteLine(String.Format("Timestamp: {0}", DateTime.Now.ToString()));
                        connectWriter.WriteLine();
                        connectWriter.Flush();

                        // Create SSL stream
                        SslStream sslStream = new SslStream(networkStream, false);
                        // Set sertificate for decrypt the client's traffic
                        sslStream.AuthenticateAsServer(_certificate, false, 
                            SslProtocols.Tls | SslProtocols.Ssl3 | SslProtocols.Ssl2, true);

                        // HTTPS server created - we can now decrypt the client's traffic
                        clientReader = new StreamReader(sslStream);
                        clientStream = sslStream;
                        // read the new http command.
                        str = clientReader.ReadLine();
                        tmpStr = str.Split(SapceSplit, 3);
                        method = tmpStr[0].ToUpper();
                        remoteUrl = remoteUrl + tmpStr[1];
                    }

但是就这一行：

sslStream.AuthenticateAsServer(_certificate, false, 
        SslProtocols.Tls | SslProtocols.Ssl3 | SslProtocols.Ssl2, true);

我收到错误：身份验证失败，因为远程方已关闭传输流。

我正在使用私钥加载证书：

_certificate = new X509Certificate2("D:\\cert2.pfx", "1234", X509KeyStorageFlags.MachineKeySet);