使用sshtunnel/Paramiko通过跳板机连接时无密码密钥认证失败

我需要用PyMySQL访问供应商AWS账户中的远程SQL服务器，该服务器通过中转网关与我司公有子网连通。已有一台EC2被加入白名单，远程网络也配置了允许访问的规则，在这台EC2上能正常执行ELT代码拉取数据。

现在尝试将该EC2作为跳板机，从本地机器连接远程SQL服务器，但遇到错误。参考@Martin Prikryl的提示后，初始化堡垒主机的代码如下：

from sshtunnel import SSHTunnelForwarder

private_key_path = 'c:\\Users\\*****\\Documents\\****.pem'
private_key = paramiko.RSAKey(filename=private_key_path)

print("Before SSHTunnelForwarder")

with SSHTunnelForwarder(
        'bastion_host',
        ssh_username="ec2-user", ssh_pkey=private_key,
        remote_bind_address=('**.***.***.***', 22),
        ssh_private_key_password="") as bastion:
    print("Inside SSHTunnelForwarder")
    bastion.start()

终端输出错误信息：

2023-12-20 12:00:39,390| ERROR   | Password is required for key C:\Users\****/.ssh\id_ed25519
Before SSHTunnelForwarder

2023-12-20 12:00:41,698| ERROR   | Could not resolve IP address for bastion_host, aborting!

同时抛出异常：

---------------------------------------------------------------------------
BaseSSHTunnelForwarderError               Traceback (most recent call last)
Cell In[9], line 9
      5 private_key = paramiko.RSAKey(filename=private_key_path)
      7 print("Before SSHTunnelForwarder")
----> 9 with SSHTunnelForwarder(
     10         'bastion_host',
     11         ssh_username="ec2-user", ssh_pkey=private_key,
     12         remote_bind_address=('**.***.***.***', 22),
     13         ssh_private_key_password="") as bastion:
     14     print("Inside SSHTunnelForwarder")
     15     bastion.start()

File c:\Users\USERNAME\pyenvironments\DataEng\Lib\site-packages\sshtunnel.py:1608, in SSHTunnelForwarder.__enter__(self)
   1606 def __enter__(self):
   1607     try:
-> 1608         self.start()
   1609         return self
   1610     except KeyboardInterrupt:

File c:\Users\USERNAME\pyenvironments\DataEng\Lib\site-packages\sshtunnel.py:1331, in SSHTunnelForwarder.start(self)
   1329 self._create_tunnels()
   1330 if not self.is_active:
-> 1331     self._raise(BaseSSHTunnelForwarderError,
   1332                 reason='Could not establish session to SSH gateway')
   1333 for _srv in self._server_list:
   1334     thread = threading.Thread(
   1335         target=self._serve_forever_wrapper,
   1336         args=(_srv, ),
   1337         name='Srv-{0}'.format(address_to_str(_srv.local_port))
   1338     )

File c:\Users\USERNAME\pyenvironments\DataEng\Lib\site-packages\sshtunnel.py:1174, in SSHTunnelForwarder._raise(self, exception, reason)
   1172 def _raise(self, exception=BaseSSHTunnelForwarderError, reason=None):
   1173     if self._raise_fwd_exc:
-> 1174         raise exception(reason)
   1175     else:
   1176         self.logger.error(repr(exception(reason)))

BaseSSHTunnelForwarderError: Could not establish session to SSH gateway

备注：

• 该密钥未设置密码
• 已尝试指定空密码
• 跳板机所在安全组允许我的IP进行SSH访问
• 可通过命令 ssh -i "***.pem" ec2-user@ec2-**-***-***-***.compute-1.amazonaws.com 成功SSH连接跳板机

内容的提问来源于stack exchange，提问作者ejwx93