FTPClient - 尝试从套接字流读取数据超时

Question

我正在尝试使用 FTPClient 连接到 vb.net 中的安全 ftp 服务器。我可以通过 filezilla 连接并上传/下载数据。但从 .net 代码来看，我遇到了超时问题。我是否犯了任何错误，或者我的以下代码中缺少任何内容？

Public Function ftpDownload(ByVal strFileName As String) As FileStream
        Try
            Dim client As New FtpClient("ftp://xxx.xxx.xxx.xxx")
            client.Port = 990
            client.Credentials = New NetworkCredential("myusername", "mypassword")
            client.EncryptionMode = FtpEncryptionMode.Explicit
            client.DataConnectionEncryption = True
            client.ReadTimeout = 20000
            client.DataConnectionType = FtpDataConnectionType.AutoPassive
            'System.Net.ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;

            client.Connect()

            Dim arr As New MemoryStream()
            client.Download(arr, strFileName)
            Using responseStream As IO.Stream = arr
                Using fs As New IO.FileStream("c:\temp\temp.123", FileMode.Create)
                    Dim buffer(2047) As Byte
                    Dim read As Integer = 0
                    Do
                        read = responseStream.Read(buffer, 0, buffer.Length)
                        fs.Write(buffer, 0, read)
                    Loop Until read = 0
                    responseStream.Close()
                    'fs.Flush()
                    'fs.Close()
                    Return fs
                End Using
                responseStream.Close()
            End Using
        Catch ex As Exception
            MsgBox(ex)
            Return Nothing
        End Try

它从 client.Connect() 抛出异常。以下是快速监视窗口中看到的异常屏幕截图：

Answer 1

错误消息让我觉得你的超时时间太短了。尝试设置一个长得离谱的超时，看看是否有流量。最坏的情况是，使用wireshark 并将您的请求与来自FileZilla 的请求进行比较。 VB 并不擅长手动数据包操作，但您的配置中可能存在一些错误，通过比较请求数据包可以发现这些错误。

Answer 2

使用端口 990 时，无法使用显式加密模式。如果需要连接到端口 990，请使用隐式加密模式。

Answer 3

用这个类来解决使用Ssh.Net方式需要依赖：Renci.SshNet.dll 在nuget搜索Ssh.Net进行安装

  /// <summary>
  /// SFTP操作类
  /// </summary>
  public class SFTPHelper
  {
    #region 字段或属性
    private SftpClient sftp;
    /// <summary>
    /// SFTP连接状态
    /// </summary>
    public bool Connected { get { return sftp.IsConnected; } }
    #endregion

    #region 构造
    /// <summary>
    /// 构造
    /// </summary>
    /// <param name="ip">IP</param>
    /// <param name="port">端口</param>
    /// <param name="user">用户名</param>
    /// <param name="pwd">密码</param>
    public SFTPHelper(string ip, string port, string user, string pwd)
    {
      sftp = new SftpClient(ip, Int32.Parse(port), user, pwd);
    }
    #endregion

    #region 连接SFTP
    /// <summary>
    /// 连接SFTP
    /// </summary>
    /// <returns>true成功</returns>
    public bool Connect()
    {
      try
      {
        if (!Connected)
        {
          sftp.Connect();
        }
        return true;
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("连接SFTP失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("连接SFTP失败，原因：{0}", ex.Message));
      }
    }
    #endregion

    #region 断开SFTP
    /// <summary>
    /// 断开SFTP
    /// </summary> 
    public void Disconnect()
    {
      try
      {
        if (sftp != null && Connected)
        {
          sftp.Disconnect();
        }
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("断开SFTP失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("断开SFTP失败，原因：{0}", ex.Message));
      }
    }
    #endregion

    #region SFTP上传文件
    /// <summary>
    /// SFTP上传文件
    /// </summary>
    /// <param name="localPath">本地路径</param>
    /// <param name="remotePath">远程路径</param>
    public void Put(string localPath, string remotePath)
    {
      try
      {
        using (var file = File.OpenRead(localPath))
        {
          Connect();
          sftp.UploadFile(file, remotePath);
          Disconnect();
        }
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("SFTP文件上传失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("SFTP文件上传失败，原因：{0}", ex.Message));
      }
    }
    #endregion

    #region SFTP获取文件
    /// <summary>
    /// SFTP获取文件
    /// </summary>
    /// <param name="remotePath">远程路径</param>
    /// <param name="localPath">本地路径</param>
    public void Get(string remotePath, string localPath)
    {
      try
      {
        Connect();
        var byt = sftp.ReadAllBytes(remotePath);
        Disconnect();
        File.WriteAllBytes(localPath, byt);
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("SFTP文件获取失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("SFTP文件获取失败，原因：{0}", ex.Message));
      }

    }
    #endregion

    #region 删除SFTP文件
    /// <summary>
    /// 删除SFTP文件 
    /// </summary>
    /// <param name="remoteFile">远程路径</param>
    public void Delete(string remoteFile)
    {
      try
      {
        Connect();
        sftp.Delete(remoteFile);
        Disconnect();
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("SFTP文件删除失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("SFTP文件删除失败，原因：{0}", ex.Message));
      }
    }
    #endregion

    #region 获取SFTP文件列表
    /// <summary>
    /// 获取SFTP文件列表
    /// </summary>
    /// <param name="remotePath">远程目录</param>
    /// <param name="fileSuffix">文件后缀</param>
    /// <returns></returns>
    public ArrayList GetFileList(string remotePath, string fileSuffix)
    {
      try
      {
        Connect();
        var files = sftp.ListDirectory(remotePath);
        Disconnect();
        var objList = new ArrayList();
        foreach (var file in files)
        {
          string name = file.Name;
          if (name.Length > (fileSuffix.Length + 1) && fileSuffix == name.Substring(name.Length - fileSuffix.Length))
          {
            objList.Add(name);
          }
        }
        return objList;
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("SFTP文件列表获取失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("SFTP文件列表获取失败，原因：{0}", ex.Message));
      }
    }
    #endregion

    #region 移动SFTP文件
    /// <summary>
    /// 移动SFTP文件
    /// </summary>
    /// <param name="oldRemotePath">旧远程路径</param>
    /// <param name="newRemotePath">新远程路径</param>
    public void Move(string oldRemotePath, string newRemotePath)
    {
      try
      {
        Connect();
        sftp.RenameFile(oldRemotePath, newRemotePath);
        Disconnect();
      }
      catch (Exception ex)
      {
        // TxtLog.WriteTxt(CommonMethod.GetProgramName(), string.Format("SFTP文件移动失败，原因：{0}", ex.Message));
        throw new Exception(string.Format("SFTP文件移动失败，原因：{0}", ex.Message));
      }
    }
    #endregion

  }