======== Tutorial ======== .. contents:: Table of Contents Below is a set of example scripts showing some of the possible customizations that can be done with pyftpdlib. Some of them are included in `demo `__ directory of pyftpdlib source distribution. Building a Base FTP server ========================== The script below is a basic configuration, and it's probably the best starting point for understanding how things work. It uses the base `DummyAuthorizer `__ for adding a bunch of "virtual" users. It also sets a limit for connections by overriding `FTPServer.max_cons `__ and `FTPServer.max_cons_per_ip `__, attributes which are intended to set limits for maximum connections to handle simultaneously and maximum connections from the same IP address. Overriding these variables is always a good idea (they default to ``0``, or "no limit") since they are a good workaround for avoiding DoS attacks. `source code `__ .. code-block:: python from pyftpdlib.authorizers import DummyAuthorizer from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer def main(): # Instantiate a dummy authorizer for managing 'virtual' users authorizer = DummyAuthorizer() # Define a new user having full r/w permissions and a read-only # anonymous user authorizer.add_user('user', '12345', '.', perm='elradfmwM') authorizer.add_anonymous(os.getcwd()) # Instantiate FTP handler class handler = FTPHandler handler.authorizer = authorizer # Define a customized banner (string returned when client connects) handler.banner = "pyftpdlib based ftpd ready." # Specify a masquerade address and the range of ports to use for # passive connections. Decomment in case you're behind a NAT. #handler.masquerade_address = '151.25.42.11' #handler.passive_ports = range(60000, 65535) # Instantiate FTP server class and listen on 0.0.0.0:2121 address = ('', 2121) server = FTPServer(address, handler) # set a limit for connections server.max_cons = 256 server.max_cons_per_ip = 5 # start ftp server server.serve_forever() if __name__ == '__main__': main() Logging management ================== Starting from version 1.0.0 pyftpdlib uses `logging `__ module to handle logging. If you don't configure logging pyftpdlib will write it to stderr by default (coloured if you're on POSIX). You can override the default behavior and, say, log to a file. What you have to bear in mind is that you should do that *before* calling serve_forever(). Examples. Logging to a file ^^^^^^^^^^^^^^^^^ .. code-block:: python import logging from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.authorizers import DummyAuthorizer authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', '.', perm='elradfmwM') handler = FTPHandler handler.authorizer = authorizer logging.basicConfig(filename='/var/log/pyftpd.log', level=logging.INFO) server = FTPServer(('', 2121), handler) server.serve_forever() Differences between logging.INFO and logging.DEBUG ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Starting from 1.0.0 logs are a lot less verbose than before. By default they look like this: :: [I 13-02-01 19:04:56] 127.0.0.1:49243-[] FTP session opened (connect) [I 13-02-01 19:04:56] 127.0.0.1:49243-[user] USER 'user' logged in. [I 13-02-01 19:04:56] 127.0.0.1:49243-[user] RETR /home/giampaolo/svn/pyftpdlib/tmp-pyftpdlib completed=1 bytes=9803392 seconds=0.025 [I 13-02-01 19:04:56] 127.0.0.1:49243-[user] FTP session closed (disconnect). To get the old behavior and log all commands and responses exchanged by client and server use: .. code-block:: python logging.basicConfig(level=logging.DEBUG) Now they will look like this: :: [I 13-02-01 19:05:42] 127.0.0.1:37303-[] FTP session opened (connect) [D 13-02-01 19:05:42] 127.0.0.1:37303-[] -> 220 pyftpdlib 1.0.0 ready. [D 13-02-01 19:05:42] 127.0.0.1:37303-[] <- USER user [D 13-02-01 19:05:42] 127.0.0.1:37303-[] -> 331 Username ok, send password. [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] <- PASS ****** [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] -> 230 Login successful. [I 13-02-01 19:05:42] 127.0.0.1:37303-[user] USER 'user' logged in. [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] <- TYPE I [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] -> 200 Type set to: Binary. [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] <- PASV [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] -> 227 Entering passive mode (127,0,0,1,233,208). [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] <- retr tmp-pyftpdlib [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] -> 125 Data connection already open. Transfer starting. [D 13-02-01 19:05:42] 127.0.0.1:37303-[user] -> 226 Transfer complete. [I 13-02-01 19:05:42] 127.0.0.1:37303-[user] RETR /home/giampaolo/svn/pyftpdlib/tmp-pyftpdlib completed=1 bytes=1000000 seconds=0.003 [D 13-02-01 19:05:42] 127.0.0.1:54516-[user] <- QUIT [D 13-02-01 19:05:42] 127.0.0.1:54516-[user] -> 221 Goodbye. [I 13-02-01 19:05:42] 127.0.0.1:54516-[user] FTP session closed (disconnect). Changing log line prefix ^^^^^^^^^^^^^^^^^^^^^^^^ .. code-block:: python ... handler = FTPHandler handler.log_prefix = 'XXX [%(username)s]@%(remote_ip)s' ... ...log will now look like this: :: [I 13-02-01 19:12:26] XXX []@127.0.0.1 FTP session opened (connect) [I 13-02-01 19:12:26] XXX [user]@127.0.0.1 USER 'user' logged in. Storing passwords as hash digests ================================= Using FTP server library with the default `DummyAuthorizer `__ means that passwords will be stored in clear-text. An end-user ftpd using the default dummy authorizer would typically require a configuration file for authenticating users and their passwords but storing clear-text passwords is of course undesirable. The most common way to do things in such case would be first creating new users and then storing their usernames + passwords as hash digests into a file or wherever you find it convenient. The example below shows how to easily create an encrypted account storage system by storing passwords as one-way hashes by using md5 algorithm. This could be easily done by using the *hashlib* module included with Python stdlib and by sub-classing the original `DummyAuthorizer `__ class overriding its `validate_authentication() `__ method. `source code `__ .. code-block:: python import os try: from hashlib import md5 except ImportError: from md5 import new as md5 # Python < 2.5 from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.authorizers import DummyAuthorizer class DummyMD5Authorizer(DummyAuthorizer): def validate_authentication(self, username, password, handler): hash = md5(password).hexdigest() return self.user_table[username]['pwd'] == hash def main(): # get a hash digest from a clear-text password hash = md5('12345').hexdigest() authorizer = DummyMD5Authorizer() authorizer.add_user('user', hash, os.getcwd(), perm='elradfmw') authorizer.add_anonymous(os.getcwd()) handler = FTPHandler handler.authorizer = authorizer server = FTPServer(('', 2121), handler) server.serve_forever() if __name__ == "__main__": main() Unix FTP Server =============== If you're running a Unix system you may want to configure your ftpd to include support for "real" users existing on the system and navigate the real filesystem. The example below uses `UnixAuthorizer `__ and `UnixFilesystem `__ classes to do so. .. code-block:: python from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.authorizers import UnixAuthorizer from pyftpdlib.filesystems import UnixFilesystem def main(): authorizer = UnixAuthorizer(rejected_users=["root"], require_valid_shell=True) handler = FTPHandler handler.authorizer = authorizer handler.abstracted_fs = UnixFilesystem server = FTPServer(('', 21), handler) server.serve_forever() if __name__ == "__main__": main() Windows FTP Server ================== The following code shows how to implement a basic authorizer for a Windows NT workstation to authenticate against existing Windows user accounts. This code requires Mark Hammond's `pywin32 `__ extension to be installed. `source code `__ .. code-block:: python from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.contrib.authorizers import WindowsAuthorizer def main(): authorizer = WindowsAuthorizer() # Use Guest user with empty password to handle anonymous sessions. # Guest user must be enabled first, empty password set and profile # directory specified. #authorizer = WindowsAuthorizer(anonymous_user="Guest", anonymous_password="") handler = FTPHandler handler.authorizer = authorizer server = FTPServer(('', 2121), handler) server.serve_forever() if __name__ == "__main__": main() Changing the concurrency model ============================== By nature pyftpdlib is asynchronous. This means it uses a single process/thread to handle multiple client connections and file transfers. This is why it is so fast, lightweight and scalable (see `benchmarks `__). The async model has one big drawback though: the code cannot contain instructions which blocks for a long period of time, otherwise the whole FTP server will hang. As such the user should avoid calls such as ``time.sleep(3)``, heavy db queries, etc. Moreover, there are cases where the async model is not appropriate, and that is when you're dealing with a particularly slow filesystem (say a network filesystem such as samba). If the filesystem is slow (say, a ``open(file, 'r').read(8192)`` takes 2 secs to complete) then you are stuck. Starting from version 1.0.0 pyftpdlib supports 2 new classes which changes the default concurrency model by introducing multiple threads or processes. In technical terms this means that every time a client connects a separate thread/process is spawned and internally it will run its own IO loop. In practical terms this means that you can block as long as you want. Changing the concurrency module is easy: you just need to import a substitute for `FTPServer `__. class: Thread-based example: .. code-block:: python from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import ThreadedFTPServer # <- from pyftpdlib.authorizers import DummyAuthorizer def main(): authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', '.') handler = FTPHandler handler.authorizer = authorizer server = ThreadedFTPServer(('', 2121), handler) server.serve_forever() if __name__ == "__main__": main() Multiple process example: .. code-block:: python from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import MultiprocessFTPServer # <- from pyftpdlib.authorizers import DummyAuthorizer def main(): authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', '.') handler = FTPHandler handler.authorizer = authorizer server = MultiprocessFTPServer(('', 2121), handler) server.serve_forever() if __name__ == "__main__": main() Throttle bandwidth ================== An important feature for an ftpd is limiting the speed for downloads and uploads affecting the data channel. `ThrottledDTPHandler.banner `__ can be used to set such limits. The basic idea behind ``ThrottledDTPHandler`` is to wrap sending and receiving in a data counter and temporary "sleep" the data channel so that you burst to no more than x Kb/sec average. When it realizes that more than x Kb in a second are being transmitted it temporary blocks the transfer for a certain number of seconds. .. code-block:: python import os from pyftpdlib.handlers import FTPHandler, ThrottledDTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.authorizers import DummyAuthorizer def main(): authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', os.getcwd(), perm='elradfmw') authorizer.add_anonymous(os.getcwd()) dtp_handler = ThrottledDTPHandler dtp_handler.read_limit = 30720 # 30 Kb/sec (30 * 1024) dtp_handler.write_limit = 30720 # 30 Kb/sec (30 * 1024) ftp_handler = FTPHandler ftp_handler.authorizer = authorizer # have the ftp handler use the alternative dtp handler class ftp_handler.dtp_handler = dtp_handler server = FTPServer(('', 2121), ftp_handler) server.serve_forever() if __name__ == '__main__': main() FTPS (FTP over TLS/SSL) server ============================== Starting from version 0.6.0 pyftpdlib finally includes full FTPS support implementing both TLS and SSL protocols and *AUTH*, *PBSZ* and *PROT* commands as defined in `RFC-4217 `__. This has been implemented by using `PyOpenSSL `__ module, which is required in order to run the code below. `TLS_FTPHandler `__ class requires at least a ``certfile`` to be specified and optionally a ``keyfile``. `Apache FAQs `__ provide instructions on how to generate them. If you don't care about having your personal self-signed certificates you can use the one in the demo directory which include both and is available `here `__. `source code `__ .. code-block:: python #!/usr/bin/env python """ An RFC-4217 asynchronous FTPS server supporting both SSL and TLS. Requires PyOpenSSL module (http://pypi.python.org/pypi/pyOpenSSL). """ from pyftpdlib.servers import FTPServer from pyftpdlib.authorizers import DummyAuthorizer from pyftpdlib.contrib.handlers import TLS_FTPHandler def main(): authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', '.', perm='elradfmw') authorizer.add_anonymous('.') handler = TLS_FTPHandler handler.certfile = 'keycert.pem' handler.authorizer = authorizer # requires SSL for both control and data channel #handler.tls_control_required = True #handler.tls_data_required = True server = FTPServer(('', 21), handler) server.serve_forever() if __name__ == '__main__': main() Event callbacks =============== A small example which shows how to use callback methods via `FTPHandler `__ subclassing: .. code-block:: python from pyftpdlib.handlers import FTPHandler from pyftpdlib.servers import FTPServer from pyftpdlib.servers import DummyAuthorizer class MyHandler(FTPHandler): def on_connect(self): print "%s:%s connected" % (self.remote_ip, self.remote_port) def on_disconnect(self): # do something when client disconnects pass def on_login(self, username): # do something when user login pass def on_logout(self, username): # do something when user logs out pass def on_file_sent(self, file): # do something when a file has been sent pass def on_file_received(self, file): # do something when a file has been received pass def on_incomplete_file_sent(self, file): # do something when a file is partially sent pass def on_incomplete_file_received(self, file): # remove partially uploaded files import os os.remove(file) def main(): authorizer = DummyAuthorizer() authorizer.add_user('user', '12345', homedir='.', perm='elradfmw') authorizer.add_anonymous(homedir='.') handler = MyHandler handler.authorizer = authorizer server = FTPServer(('', 2121), handler) server.serve_forever() if __name__ == "__main__": main() Command line usage ================== Starting from version 0.6.0 pyftpdlib can be run as a simple stand-alone server via Python's -m option, which is particularly useful when you want to quickly share a directory. Some examples. Anonymous FTPd sharing current directory: .. code-block:: sh $ python -m pyftpdlib [I 13-04-09 17:55:18] >>> starting FTP server on 0.0.0.0:2121, pid=6412 <<< [I 13-04-09 17:55:18] poller: [I 13-04-09 17:55:18] masquerade (NAT) address: None [I 13-04-09 17:55:18] passive ports: None [I 13-04-09 17:55:18] use sendfile(2): True Anonymous FTPd with write permission: .. code-block:: sh $ python -m pyftpdlib -w Set a different address/port and home directory: .. code-block:: sh $ python -m pyftpdlib -i localhost -p 8021 -d /home/someone See ``python -m pyftpdlib -h`` for a complete list of options.