FsTPy

Bridging FTP servers and cloud storage.

FsTPy brings together the power and scalability of pyftpdlib (https://github.com/giampaolo/pyftpdlib) with the flexibility and abstraction provided by PyFilesystem2 (https://github.com/PyFilesystem/pyfilesystem2).

It allows to build custom FTP and FTPS servers on abstracted filesystem (local or cloud such as S3 or Dropbox or Google Drive)

Installation

Install from pypi with pip:

pip3 install FsTPy

Standalone Server

The package comes with an executable server which can be used as a starting point for custom solutions. The script reqires to be executed in a folder containing three files

• credentials.txt a file with login information
• server.key SSL key of the server
• server.crt Certificate of the server

Server key and certificate can be generated following the guide https://httpd.apache.org/docs/2.4/ssl/ssl_faq.html#selfcert or any similar proecdure.

The credentials file credentials.txt should be formatted as follows

credentials.txt

This files contains a column separated list of username, md5 password hash, root directory, user permissions permissions and optional login and logout messages. Different lines can be defined in order to define different user credentials.

The following example of credentials.txt defines two users with the same password (12345) but different permissions.

user1;827ccb0eea8a706c4c34a16891f84e7b;/;elradfmwMT;Welcome, user1!;Bye, bye user1
user2;827ccb0eea8a706c4c34a16891f84e7b;/;elr;Welcome, user2!;Bye, bye user2

User Permissions

Permission argument is a string referencing the user's permissions explained below:

Read permissions:

• "e" = change directory (CWD command)
• "l" = list files (LIST, NLST, STAT, MLSD, MLST, SIZE, MDTM commands)
• "r" = retrieve file from the server (RETR command)

Write permissions:

• "a" = append data to an existing file (APPE command)
• "d" = delete file or directory (DELE, RMD commands)
• "f" = rename file or directory (RNFR, RNTO commands)
• "m" = create directory (MKD command)
• "w" = store a file to the server (STOR, STOU commands)
• "M" = change file mode (SITE CHMOD command)
• "T" = update file last modified time (MFMT command)

Running the server

Once installed, the server can be run simply by providing the PyFilesystem2 URL of the desired filesystem .

The server binds to 0.0.0.0:2121. See help to change the address and port arguments:

fstpyd --help

Running an S3 backed server

In order to start an S3 backed FTPS server on bucket my-bucket:

1. Install S3 extension for PyFilesysytem2:

pip3 install fs-s3fs

2. Run the server on the desired S3 bucket:

fstpyd 's3://AWS_ACCESS_KEY_ID:AWS_SECRET_ACCESS_KEY@my-bucket/'

Running a server on local storage

Run the server on a given root directory:

fstpyd 'osfs://path/to/rootdir/'

APIs

The API is pretty simple. It extends some classes of the pyftpdlib library (https://github.com/giampaolo/pyftpdlib). The fstpyd script (https://github.com/desmoteo/FsTPy/blob/main/scripts/fstpyd) can be used to understand basic usage, in combination with the rich documentation of pyftpdlib (https://pyftpdlib.readthedocs.io/en/latest/index.html) and PyFilesystem2 (https://docs.pyfilesystem.org/en/latest/index.html)

There are just a couple of differences with respect to the original pyftpdlib.

Authorizers

The authorizers from fstpy.authorizers, DummyAuthorizer and MD5Authorizer repalce the corresponfing classes of pyftpdlib. They take two arguments , the URL of the filesystem in PyFilesystem2 format, and the path to the credentials file.

DummyAuthorizer expects a credentials file with plain passwords. MD5Authorizer expects a credentials file with MD5 hashes of the passwords.

from fstpy.authorizers import MD5Authorizer

authorizer = MD5Authorizer('s3://my-bucket', 'credentials.txt')

Abstraced Filesystem

FsTPy Abstracted filesystem in fstpy.filesystems should replace the native abstracted_fs of pyftpdlib handlers

from fstpy.filesystems import AbstractedFS
from pyftpdlib.handlers import TLS_FTPHandler

handler = TLS_FTPHandler
handler.abstracted_fs = AbstractedFS