实现

def get_ssh_tunnel(middle_name, remote_name, localport):
    session = models.get_db_session()
    middle_host = session.query(models.Server).filter(models.Server.name == middle_name).one()
    remote_host = session.query(models.Server).filter(models.Server.name == remote_name).one()
    return SSHTunnelForwarder(
        (middle_host.host, int(middle_host.port)),
        ssh_username=middle_host.username,
        ssh_password=middle_host.password,
        remote_bind_address=(remote_host.host, int(remote_host.port)),
        local_bind_address=("0.0.0.0", int(localport))
    ), middle_host, remote_host

参考

https://pypi.org/project/sshtunnel/