ftpsmin - Minimal Secure FTP Server for Windows

A minimal, secure FTP server for Windows with TLS support, virtual directories, and Windows Service integration.

Features

• FTPS (FTP over TLS) - Both explicit (AUTH TLS) and implicit TLS modes
• Virtual Directories - Map multiple physical directories to virtual paths
• Per-Directory Permissions - Read-only and hidden directory options
• UTF-8 Support - Full Unicode filename support
• Resume Transfers - REST command for resuming interrupted transfers
• Windows Service - Run as a Windows service with easy install/uninstall
• JSON Configuration - Simple, human-readable configuration file
• MLSD/MLST - Machine-readable directory listings (RFC 3659)
• Multi-threaded - Handles multiple simultaneous connections

Quick Start

1. Download the latest release from the Releases page

2. Generate a configuration file:

   ftpsmin.exe -genconfig

3. Edit ftpsmin.json to configure your server

4. Generate SSL certificate (optional, for FTPS):

   openssl req -x509 -newkey rsa:4096 -keyout server.key -out server.crt -days 365 -nodes

5. Run the server:

   ftpsmin.exe

Installation as Windows Service

# Install the service
ftpsmin.exe -install

# Start the service
ftpsmin.exe -start

# Check status
ftpsmin.exe -status

# Stop the service
ftpsmin.exe -stop

# Uninstall the service
ftpsmin.exe -uninstall

Configuration

Example ftpsmin.json:

{
    "port": 21,
    "passivePortStart": 50000,
    "passivePortEnd": 50100,

    "virtualDirs": [
        {
            "virtual": "/public",
            "physical": "C:\\FTP\\Public",
            "readOnly": false,
            "hidden": false
        },
        {
            "virtual": "/archive",
            "physical": "D:\\Archive",
            "readOnly": true,
            "hidden": false
        }
    ],

    "useTLS": true,
    "certFile": "server.crt",
    "keyFile": "server.key",

    "requireAuth": true,
    "username": "ftpuser",
    "password": "yourpassword",

    "defaultUtf8": true
}

Configuration Options

Option	Description	Default
port	Control port number	21
hostAddress	External IP address (for NAT)	(empty/auto-detect)
passivePortStart	Start of passive port range	0 (random)
passivePortEnd	End of passive port range	0 (random)
virtualDirs	Array of virtual directory mappings	[]
useTLS	Enable TLS support	false
implicitTLS	Use implicit TLS (port 990)	false
certFile	Path to SSL certificate	server.crt
keyFile	Path to SSL private key	server.key
requireAuth	Require username/password	false
username	Username for authentication	Anonymous
password	Password for authentication	(empty)
defaultUtf8	Enable UTF-8 by default	true
getOnly	Read-only mode (no uploads)	false
logFile	Path to log file	(empty/disabled)
logLevel	Log verbosity (0-3)	2
maxConnections	Maximum simultaneous connections	10
idleTimeout	Idle timeout in seconds	300
transferTimeout	Transfer timeout in seconds	600
serviceName	Windows service name	ftpsmin
serviceDisplayName	Service display name	FTPSMIN Secure FTP Server
serviceDescription	Service description	(see code)

Command Line Options

ftpsmin [options]

Options:
  -c <file>     Use specified JSON config file (default: ftpsmin.json)
  -genconfig    Generate sample configuration file
  -install      Install as Windows service
  -uninstall    Uninstall Windows service
  -start        Start the Windows service
  -stop         Stop the Windows service
  -status       Check Windows service status
  -h, -help     Show help message
  -version      Show version information

Building from Source

Prerequisites

• Visual Studio 2019/2022 or MinGW-w64
• OpenSSL development libraries

Build with Visual Studio

# Open Developer Command Prompt
nmake

License

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

Acknowledgments

Based on the original ftpdmin by Matthias Wandel.