Question

我在WPF应用程序上使用Renci SSH.Net库，我在使用SFTP客户端时遇到了问题。当用户尝试连接以从SFTP服务器下载某些文件时，他会收到如下所示的消息：

服务器响应不包含ssh协议标识

它似乎不是服务器的特定内容，因为我能够在我的开发桌面和辅助笔记本电脑上正常连接和下载文件。相同的应用程序可以通过SSH连接并运行命令而不会出现问题，它只是SFTP连接似乎是问题所在。我正在寻找一些关于从何处开始排除故障的指导。

SFTP代码如下所示：

void DownloadPlogs()
    {
        try
        {
            SftpClient SFTP;
            if (GV.UseCustomPort && GV.CustomPort > 0 && GV.CustomPort < 65535)
            {
                SFTP = new SftpClient(GV.IpAddress, GV.CustomPort, GV.Username, GV.Password);
            }
            else
            {
                SFTP = new SftpClient(GV.IpAddress, 22, GV.Username, "");
            }
            SFTP.Connect();

            DownloadDirectory(SFTP, "/PLOG", Directory.GetCurrentDirectory() + @"\PLOG");
            ZipFile.CreateFromDirectory("PLOG", String.Format("{0} - {1} PLOGS.zip", GV.IpAddress, DateTime.Now.ToString("yyyyMMddHHmmss")));
            Directory.Delete(Directory.GetCurrentDirectory() + @"\PLOG", true);

            SFTP.Disconnect();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "Error Getting PLOGS");
        }
    }

    void DownloadDirectory(SftpClient Client, string Source, string Destination)
    {
        var Files = Client.ListDirectory(Source);
        foreach (var File in Files)
        {
            if (!File.IsDirectory && !File.IsSymbolicLink)
            {
                DownloadFile(Client, File, Destination);
            }
            else if (File.IsSymbolicLink)
            {
                //Ignore
            }
            else if (File.Name != "." && File.Name != "..")
            {
                var Dir = Directory.CreateDirectory(System.IO.Path.Combine(Destination, File.Name));
                DownloadDirectory(Client, File.FullName, Dir.FullName);
            }
        }
    }

    void DownloadFile(SftpClient Client, Renci.SshNet.Sftp.SftpFile File, string Directory)
    {
        using (Stream FileStream = System.IO.File.OpenWrite(System.IO.Path.Combine(Directory, File.Name)))
        {
            Client.DownloadFile(File.FullName, FileStream);
        }
    }

以下SSH代码：

public SshConnection(string Host, int Port, string Username, string Password)
    {
        myClient = new SshClient(Host, Port, Username, Password);
        myClient.KeepAliveInterval = new TimeSpan(0, 0, 5);
        myClient.HostKeyReceived += myClient_HostKeyReceived;
        myClient.ErrorOccurred += myClient_ErrorOccurred;
    }

void myClient_ErrorOccurred(object sender, Renci.SshNet.Common.ExceptionEventArgs e)
    {
        MessageBox.Show(e.Exception.Message, "SSH Error Occurred");
    }

    void myClient_HostKeyReceived(object sender, Renci.SshNet.Common.HostKeyEventArgs e)
    {
        e.CanTrust = true;
    }

    public async void Connect()
    {
        Task T = new Task(() =>
        {
            try
            {
                myClient.Connect();
            }
            catch (System.Net.Sockets.SocketException)
            {
                MessageBox.Show("Invalid IP Address or Hostname", "SSH Connection Error");
            }
            catch (Renci.SshNet.Common.SshAuthenticationException ex)
            {
                MessageBox.Show(ex.Message, "SSH Authentication Error");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.StackTrace, ex.Message);
                MessageBox.Show(ex.GetType().ToString());
                OnConnection(this, new ConnectEventArgs(myClient.IsConnected));
            }
        });

        T.Start();
        await T;
        if (T.IsCompleted)
        {
            OnConnection(this, new ConnectEventArgs(myClient.IsConnected));
        }
    }

    public void Disconnect()
    {
        try
        {
            myClient.Disconnect();
            OnConnection(this, new ConnectEventArgs(myClient.IsConnected));
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.StackTrace, ex.Message);
        }
    }

    public void SendData(string Data)
    {
        try
        {
            if (Data.EndsWith("\r\n"))
            {
                RunCommandAsync(Data, SshCommandRx);
            }
            else
            {
                RunCommandAsync(String.Format("{0}\r\n",Data), SshCommandRx);
            }
            //SshCommand Command = myClient.RunCommand(Data);
            //OnDataReceived(this, new DataEventArgs(Command.Result));
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.StackTrace, ex.Message);
        }
    }

    private async void RunCommandAsync(String Data, SshCommandCallback Callback)
    {
        Task<SshCommand> T = new Task<SshCommand>(() =>
        {
            try
            {
                SshCommand Command = myClient.RunCommand(Data);
                return Command;
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, ex.GetType().ToString());
                return null;
            }
        });

        T.Start();
        await T;
        if (T.IsCompleted)
        {
            Callback(this, T.Result);
        }
    }

    private void SshCommandRx(SshConnection C, SshCommand Command)
    {
        if (Command != null)
        {
            string Rx = Command.Result;
            //if (Rx.StartsWith(Command.CommandText))
            //{
            //    Rx = Rx.Remove(0, Command.CommandText.Length);
            //}
            while (Rx.EndsWith("\r\n\r\n") == false)
            {
                Rx += "\r\n";
            }
            OnDataReceived(this, new DataEventArgs(Rx));
        }
    }

Answer 1

我只通过连接重试尝试来解决它。没有找到究竟是什么问题，但多次出现此连接问题。

示例：

int attempts = 0;
            do
            {
                try
                {
                    client.Connect();
                }
                catch (Renci.SshNet.Common.SshConnectionException e)
                {
                    attempts++;
                }
            } while (attempts < _connectiontRetryAttempts && !client.IsConnected);

Answer 2

I experienced the same odd error message when attempting to connect to a SFTP server while using the SSH.NET library in a program on the server. The problem did not appear while testing from my development machine.

The solution was to have our server team add the IP address of the server into the hosts.allow file on the SFTP Linux server.

Renci.SshNet：＆＃34;服务器响应不包含ssh协议标识＆＃34;

2 个答案: