Modern Python Standard Library Cookbook

How it works...

The FTPClient class provides an initializer that is in charge of setting up the correct connection to the server and a bunch of methods to actually do work against the connected server.

__init__ does quite a lot of work to try setting up the proper connection to the remote server:

def __init__(self, host, username='', password=''):
    self._client = ftplib.FTP_TLS(timeout=10)
    self._client.connect(host)

    # enable TLS
    try:
        self._client.auth()
    except ftplib.error_perm:
        # TLS authentication not supported
        # fallback to a plain FTP client
        self._client.close()
        self._client = ftplib.FTP(timeout=10)
        self._client.connect(host)

    self._client.login(username, password)

    if hasattr(self._client, 'prot_p'):
        self._client.prot_p()

First it tries ...