如果對SFTP or FTPS 有過一點點了解的話，那麼你肯定知道Renci.SshNet。

其中SftpClient類的建構函式需要傳輸，遠端伺服器地址、埠、使用者名稱、密碼（有些還有私鑰）。下面只是用到賬戶密碼即可，暫時就不說祕鑰了。

當你建立了這個例項之後，就可以Connect();開啟伺服器連線了。

通過ListDirectory()方法你就可以拿到遠端目錄的檔案了。伺服器初始檔案目錄地址為"/",當你那你子目錄或者檔案即可進行操作。

通過Delete()方法你可以直接根據遠端目錄直接刪除檔案 or 資料夾//"/Test.txt"

通過DownloadFile()方法你可以直接更具遠端目錄以及建立的檔案下載檔案。

通過UploadFile()方法你可以把本地檔案的流上傳到遠端目錄。

如有問題，我們可以繼續探討。

 public class SFTP
    {
        #region 欄位或屬性
        private SftpClient sftp;
        /// <summary>
        /// SFTP連線狀態
        /// </summary>
        public bool Connected { get { return sftp.IsConnected; } }
        #endregion

        #region
 
 構造
        /// <summary>
        /// 構造
        /// </summary>
        /// <param name="ip">IP</param>
        /// <param name="port">埠</param>
        /// <param name="user">使用者名稱</param>
        /// <param name="pwd">密碼</param>
        public SFTPOperation(string
 
 ip, string port, string user, string pwd)
        {
            sftp = new SftpClient(ip, Int32.Parse(port), user, pwd);
        }

        public SFTPOperation(string ip, int port, string user, string pwd)
        {
            var authMethods = new List<AuthenticationMethod>();
            var keyboardAuthMethod = new KeyboardInteractiveAuthenticationMethod(user);//鍵盤模擬連線
            keyboardAuthMethod.AuthenticationPrompt += delegate (Object senderObject, AuthenticationPromptEventArgs eventArgs)
            {
                foreach (var prompt in eventArgs.Prompts)
                {
                    if (prompt.Request.Equals("Password: ", StringComparison.InvariantCultureIgnoreCase))
                    {
                        prompt.Response = pwd;
                    }
                }
            };
            authMethods.Add(new PasswordAuthenticationMethod(user, pwd));
            authMethods.Add(keyboardAuthMethod);
            var connection = new ConnectionInfo(ip, port, user, authMethods.ToArray());
            sftp = new SftpClient(connection);
            sftp.Connect();
        }

        public SFTPOperation(string ip, int port, string user, string passphrase, string keypath)
        {
            var key = File.ReadAllText(keypath);
            PrivateKeyFile keyFile = null;
            using (var buf = new MemoryStream(Encoding.UTF8.GetBytes(key)))
            {
                if (string.IsNullOrWhiteSpace(passphrase))
                {
                    keyFile = new PrivateKeyFile(buf);
                }
                else
                {
                    keyFile = new PrivateKeyFile(buf, passphrase);
                }
            }

            var keyFiles = new[] { keyFile };
            var methods = new List<AuthenticationMethod>
                {
                    new PrivateKeyAuthenticationMethod(user, keyFiles)
                };
            var connection = new ConnectionInfo(ip, port, user, methods.ToArray());
            sftp = new SftpClient(connection);
            sftp.Connect();
        }
        #endregion

        #region 連線SFTP
        /// <summary>
        /// 連線SFTP
        /// </summary>
        /// <returns>true成功</returns>
        public bool Connect()
        {
            try
            {
                if (!Connected)
                {
                    sftp.Connect();
                }
                return true;
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("連線SFTP失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

        #region 斷開SFTP
        /// <summary>
        /// 斷開SFTP
        /// </summary> 
        public void Disconnect()
        {
            try
            {
                if (sftp != null && Connected)
                {
                    sftp.Disconnect();
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("斷開SFTP失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

        #region SFTP上傳檔案
        /// <summary>
        /// SFTP上傳檔案
        /// </summary>
        /// <param name="localPath">本地路徑</param>
        /// <param name="remotePath">遠端路徑</param>
        public bool Put(string localPath, string remotePath, bool successCloseConnect = false)
        {
            try
            {
                using (var file = File.OpenRead(localPath))
                {
                    Connect();
                    sftp.UploadFile(file, remotePath);
                    Console.WriteLine("上傳成功");
                    if (successCloseConnect)
                    {
                        Disconnect();
                    }
                }
                return true;
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案上傳失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

        #region SFTP獲取檔案
        /// <summary>
        /// SFTP獲取檔案
        /// </summary>
        /// <param name="remotePath">遠端路徑</param>
        /// <param name="localPath">本地路徑</param>
        public void Get(string remotePath, string localPath)
        {
            try
            {
                //Connect();
                //var test = sftp.Get(remotePath);
                var byt = sftp.ReadAllBytes(remotePath);
                //Disconnect();
                //建立寫入流
                using (var fs = new FileStream(localPath, FileMode.CreateNew))
                {
                    var stream = new MemoryStream(byt);
                    byte[] bytes = new byte[1024];
                    int count = 0;
                    int readCount = 0; //從相應流中讀取到的檔案大小
                    while ((count = stream.Read(bytes, 0, bytes.Length)) > 0)
                    {
                        //寫入檔案
                        fs.Write(bytes, 0, count);
                        //清空
                        fs.Flush();
                        readCount += count;
                    }
                    stream.Close();
                    var Count = readCount;
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案獲取失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }

        }

        public void GetFile(string remotePath, string localPath)
        {
            try
            {
                //建立寫入流
                //using (var fs = new FileStream(localPath, FileMode.CreateNew))
                using (var fs = File.OpenWrite(localPath))
                {
                    sftp.DownloadFile(remotePath, fs);
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案獲取失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }

        }
        #endregion

        #region 刪除SFTP檔案
        /// <summary>
        /// 刪除SFTP檔案 
        /// </summary>
        /// <param name="remoteFile">遠端路徑</param>
        public void Delete(string remoteFile, bool closeClient = false)
        {
            try
            {
                Connect();
                sftp.Delete(remoteFile);
                if (closeClient)
                {
                    Disconnect();
                }
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案刪除失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

        #region 獲取SFTP檔案列表
        /// <summary>
        /// 獲取SFTP檔案列表
        /// </summary>
        /// <param name="remotePath">遠端目錄</param>
        /// <param name="fileSuffix">檔案字尾</param>
        /// <returns></returns>
        public List<string> GetFileList(string remotePath, string fileSuffix)
        {
            try
            {
                //Connect();
                var files = sftp.ListDirectory(remotePath);
                //Disconnect();
                var list = new List<string>();
                foreach (var file in files)
                {
                    string name = file.Name;
                    if (name.Length > (fileSuffix.Length + 1) && fileSuffix == name.Substring(name.Length - fileSuffix.Length))
                    {
                        list.Add(name);
                    }
                }
                return list;
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案列表獲取失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

        #region 移動SFTP檔案
        /// <summary>
        /// 移動SFTP檔案
        /// </summary>
        /// <param name="oldRemotePath">舊遠端路徑</param>
        /// <param name="newRemotePath">新遠端路徑</param>
        public void Move(string oldRemotePath, string newRemotePath)
        {
            try
            {
                Connect();
                sftp.RenameFile(oldRemotePath, newRemotePath);
                Disconnect();
            }
            catch (Exception ex)
            {
                throw new Exception(string.Format("SFTP檔案移動失敗，原因：{0}", ex.InnerException != null ? ex.InnerException.Message : ex.Message));
            }
        }
        #endregion

    }