Dart FTP Server

A simple, extensible FTP server implementation in Dart. Supports both read-only and read-and-write modes, with pluggable file system backends for flexible directory exposure and security.

Table of Contents

  1. Quick Start
  2. Features
  3. Compatibility
  4. Usage
  5. File Sharing Backends
  6. Contributing
  7. License

1. Quick Start

import 'package:ftp_server/ftp_server.dart';
import 'package:ftp_server/server_type.dart';
import 'package:ftp_server/file_operations/virtual_file_operations.dart';

void main() async {
  final fileOps = VirtualFileOperations([
    '/home/user/ftp',
    '/home/user/other',
  ]);

  final server = FtpServer(
    21, // port
    username: 'user',
    password: 'pass',
    fileOperations: fileOps,
    serverType: ServerType.readAndWrite, // or ServerType.readOnly
  );

  await server.start();
}
  • See File Sharing Backends for how to use a single directory (Physical backend).
  • For more advanced usage, see the sections below.

2. Features

  • Passive and Active Modes: Supports both passive and active data connections.
  • File Operations: Retrieve, store, delete, and list files.
  • Directory Operations: Change, make, and remove directories.
  • Read-Only Mode: Disable write operations for enhanced security.
  • Authentication: Basic username and password authentication.

3. Compatibility

Tested on macOS. CI/CD test cases ensure compatibility with Linux and Windows.

4. Usage

4.1 Starting the Server

See Quick Start above for a basic example.

Using PhysicalFileOperations

If you want to use a single physical directory as the FTP root (with no virtual mapping):

import 'package:ftp_server/ftp_server.dart';
import 'package:ftp_server/server_type.dart';
import 'package:ftp_server/file_operations/physical_file_operations.dart';

void main() async {
  final fileOps = PhysicalFileOperations('/home/user/ftp_root');

  final server = FtpServer(
    21, // port
    username: 'user',
    password: 'pass',
    fileOperations: fileOps,
    serverType: ServerType.readAndWrite, // or ServerType.readOnly
  );

  await server.start();
}

4.2 Running in the Background

You can run the FTP server in the background using the provided method:

await server.startInBackground();

This allows your Dart application to continue running other code while the FTP server handles connections in the background.

4.3 Supported FTP Commands

Command Description
USER <username> Set the username for authentication.
PASS <password> Set the password for authentication.
QUIT Close the control connection.
PASV Enter passive mode.
PORT <host-port> Enter active mode.
LIST [<directory>] List files in the specified directory or current directory.
RETR <filename> Retrieve the specified file.
STOR <filename> Store a file.
CWD <directory> Change the current directory.
CDUP Change to the parent directory.
MKD <directory> Make a new directory.
RMD <directory> Remove a directory.
DELE <filename> Delete a file.
PWD Print the current directory.
SYST Return system type.
NOOP No operation (used to keep the connection alive).
SIZE <filename> Return the size of the specified file.
RNFR <filename> Rename from (specify source file/directory for rename).
RNTO <filename> Rename to (specify destination file/directory for rename).
RENAME <old> <new> Rename a file or directory (high-level command).

4.4 Authentication

To enable authentication, provide the username and password parameters when creating the FtpServer instance. The server will then require clients to log in using these credentials.

4.5 Read-Only Mode

To run the server in read-only mode, set the serverType parameter to ServerType.readOnly. In this mode, commands that modify the filesystem (e.g., STOR, DELE, MKD, RMD) will be disabled.

5. File Sharing Backends

This project provides two ways to share files and folders over FTP:

5.1 Quick Comparison

Feature Virtual (Multiple Directories) Physical (Single Directory)
Number of shared folders Multiple One
Can add/edit/delete at root? No Yes
Root meaning Virtual root (not a real folder) The folder you chose as the root
Best for Sharing several separate folders Sharing one folder and its content

5.2 Virtual (Multiple Directories)

  • Lets you share several folders, and each appears as a separate top-level folder when users connect.
  • Users cannot add, edit, or delete files directly at the root ("/"). They can only work inside the folders you shared.
  • Example: If you share /photos and /docs, users will see two folders: photos and docs at the top level.
  • Use this if: You want to share multiple folders and keep them separate.

5.3 Physical (Single Directory)

  • Lets you share one folder as the root of the FTP server.
  • Users can add, edit, or delete files and folders directly inside this root folder.
  • Example: If you share /home/user/ftp_root, users will see all files and folders inside ftp_root and can manage them freely.
  • Use this if: You want to share everything inside a single folder and allow full access within it.

5.4 Choosing a Backend

  • Use VirtualFileOperations if you want to expose multiple directories as top-level folders or need to restrict access to specific directories.
  • Use PhysicalFileOperations for direct, simple access to a single directory tree, with no virtual mapping, and if you need to allow operations at the root directory.

5.5 Key Points

  • Both implementations enforce boundaries: you cannot access or modify files outside the allowed root(s).
  • Neither implementation allows deleting the root directory (/). Attempting to do so will throw an error.
  • VirtualFileOperations is stricter: it prevents any file or directory creation, deletion, or writing directly at the virtual root (/).
  • PhysicalFileOperations allows creating and writing files at its root, but not deleting it (the root is the directory you provided, not the system root).

6. Contributing

Contributions are welcome! Please fork the repository and submit a pull request with your changes. Make sure to follow the existing code style and include tests for new features.

7. License

This project is licensed under the MIT License. See the LICENSE file for details.

Libraries

file_operations/file_operations
file_operations/physical_file_operations
file_operations/virtual_file_operations
ftp_command_handler
ftp_server
ftp_session
logger_handler
server_type