需要借助Paramiko，Paramiko模块是基于Python实现的SSH远程安全连接，用于SSH远程执行命令、文件传输等功能

默认Python没有自带，需要手动安装：
pip3 install paramiko

上传文件

# -*- coding: utf-8 -*-
import paramiko

def sftp_upload_file(host,user,password,server_path, local_path,timeout=10):
    """
    上传文件，注意：不支持文件夹
    :param host: 主机名
    :param user: 用户名
    :param password: 密码
    :param server_path: 远程路径，比如：/home/sdn/tmp.txt
    :param local_path: 本地路径，比如：D:/text.txt
    :param timeout: 超时时间(默认)，必须是int类型
    :return: bool
    """
    try:
        t = paramiko.Transport((host, 22))
        t.banner_timeout = timeout
        t.connect(username=user, password=password)
        sftp = paramiko.SFTPClient.from_transport(t)
        sftp.put(local_path, server_path)
        t.close()
        return True
    except Exception as e:
        print(e)
        return False

下载文件

def sftp_down_file(host,user,password,server_path, local_path,timeout=10):
    """
    下载文件，注意：不支持文件夹
    :param host: 主机名
    :param user: 用户名
    :param password: 密码
    :param server_path: 远程路径，比如：/home/sdn/tmp.txt
    :param local_path: 本地路径，比如：D:/text.txt
    :param timeout: 超时时间(默认)，必须是int类型
    :return: bool
    """
    try:
        t = paramiko.Transport((host,port))
        t.banner_timeout = timeout
        t.connect(username=user,password=password)
        sftp = paramiko.SFTPClient.from_transport(t)
        sftp.get(server_path, local_path)
        t.close()
        return True
    except Exception as e:
        print(e)
        return False

Paramiko不支持下载目录，如果要下载目录下所有文件到本地，需要遍历下载

def sftp_down_all_files(self, remote_path, local_path):
    try:
        t = paramiko.Transport((self.ip, self.port))
        t.connect(username=self.username, password=self.password)
        sftp = paramiko.SFTPClient.from_transport(t)
        all_files = sftp_get_all_files(self, remote_path)
        for x in all_files:
            local_file = local_path + "\\" + x
            remote_file = remote_path +"/" + x
            print  local_file
            sftp.get(remote_file, local_file)
        t.close()
        return True
    except Exception as e:
        print(e)
        return False

def sftp_get_all_files(self, remote_path):
  try:
        t = paramiko.Transport((self.ip, self.port))
        t.connect(username=self.username, password=self.password)
        sftp = paramiko.SFTPClient.from_transport(t)
        all_files = list()
        files = sftp.listdir_attr(remote_path)
        for x in files:
            all_files.append(x.filename)
        return all_files
    except Exception as e:
        print(e)
        return all_files