Simple Secure FTP Daemon (simple-sftpd)

A secure, configurable, and feature-rich FTP server written in C++ for Linux, macOS, and Windows.

Features

Core FTP Functionality

RFC 959 Compliant: Full FTP protocol implementation
Passive Mode: Full PASV support with data connections
Active Mode: Full PORT command support
File Transfer: Upload, download, append, and resume support
Directory Operations: List, create, remove, and navigate directories
File Management: Delete, rename, and directory operations

Security Features

SSL/TLS Support: Full FTPS implementation with OpenSSL
User Authentication: Username/password and PAM authentication
Access Control: Basic permissions, path restrictions, and IP whitelisting
Path Validation: Directory traversal protection and home directory enforcement
Chroot Support: Directory isolation and privilege dropping
Rate Limiting: Time-window based protection against abuse and DoS attacks
Bandwidth Throttling: Upload and download speed limits

Virtual Hosting

Multi-Domain Support: Host multiple FTP sites on one server
Per-Host Configuration: Individual settings for each virtual host
SSL Certificate Management: Separate certificates per domain
Access Control: User restrictions per virtual host

User Management

Flexible Permissions: Granular control over user capabilities
Anonymous Access: Configurable anonymous user support
Guest Accounts: Limited access for temporary users
Connection Limits: Per-user connection and transfer restrictions
Session Management: Timeout and activity tracking

Performance & Monitoring

Multi-threaded: Efficient handling of multiple connections
Connection Management: Thread-safe connection tracking and cleanup
Transfer Optimization: Basic file transfers (sendfile and memory-mapped I/O in v0.2.0)
Statistics: Basic metrics (comprehensive statistics in v0.2.0)
Logging: Advanced logging with STANDARD, JSON, and EXTENDED formats

Platform Support

Cross-Platform: Linux, macOS, and Windows
Native Builds: Optimized for each platform
Package Management: DEB, RPM, PKG, and MSI packages
Service Integration: systemd, launchd, and Windows services

Quick Start

🐳 Docker (Recommended)

The fastest way to get started with simple-sftpd is using Docker:

# Clone the repository
git clone https://github.com/simple-sftpd/simple-sftpd.git
cd simple-sftpd

# Quick start with Docker
cd deployment/examples/docker
docker-compose up -d

# Test the FTP service
nc -z localhost 21

Docker Features:

✅ Zero dependencies - No need to install build tools
✅ Cross-platform - Works on Linux, macOS, Windows
✅ Production-ready - Optimized runtime image
✅ Development environment - Full debugging tools included
✅ Multi-architecture - x86_64, ARM64, ARMv7 support

For detailed Docker deployment, see Docker Deployment Guide.

Traditional Installation

Prerequisites

C++17 Compiler: GCC 7+, Clang 5+, or MSVC 2017+
CMake 3.16+: Build system
OpenSSL: SSL/TLS support
jsoncpp: JSON configuration parsing

From Source

# Clone the repository
git clone https://github.com/simple-sftpd/simple-sftpd.git
cd simple-sftpd

# Build the project
make install-dev  # Install development dependencies
make build        # Build the application
make install      # Install system-wide

From Packages

Ubuntu/Debian:

sudo apt update
sudo apt install simple-sftpd

CentOS/RHEL:

sudo yum install simple-sftpd
# or
sudo dnf install simple-sftpd

macOS:

brew install simple-sftpd

Configuration

simple-sftpd supports multiple configuration formats (INI, JSON, YAML) and provides example configurations for different use cases:

Configuration Formats:

INI (.conf) - Traditional format, fully supported
JSON (.json) - Machine-readable format (parser pending)
YAML (.yml) - Human-readable format (parser pending)

Example Configurations:

config/simple/ - Minimal configuration for basic setups
config/advanced/ - Enhanced configuration with SSL/TLS and performance tuning
config/production/ - Hardened configuration for production deployments

Choose and copy a configuration:

# For simple setup
sudo cp config/simple/simple-sftpd.conf /etc/simple-sftpd/simple-sftpd.conf

# For advanced setup
sudo cp config/advanced/simple-sftpd.conf /etc/simple-sftpd/simple-sftpd.conf

# For production
sudo cp config/production/simple-sftpd.conf /etc/simple-sftpd/simple-sftpd.conf

Edit the configuration file:

sudo nano /etc/simple-sftpd/simple-sftpd.conf

Create necessary directories:

sudo mkdir -p /var/ftp /var/log/simple-sftpd
sudo chown ftp:ftp /var/ftp

For detailed configuration options, see Configuration Guide.

Running the Server

Basic Usage

# Start in foreground (for testing)
sudo simple-sftpd start --config /etc/simple-sftpd/simple-sftpd.conf

# Start as daemon
sudo simple-sftpd --daemon start

# Test configuration
simple-sftpd --test-config --config /etc/simple-sftpd/simple-sftpd.conf

Service Management

Linux (systemd):

sudo systemctl enable simple-sftpd
sudo systemctl start simple-sftpd
sudo systemctl status simple-sftpd

macOS (launchd):

sudo launchctl load /Library/LaunchDaemons/com.blburns.simple-sftpd.plist
sudo launchctl start com.blburns.simple-sftpd

Windows:

sc create simple-sftpd binPath= "C:\Program Files\simple-sftpd\bin\simple-sftpd.exe"
sc start simple-sftpd

Configuration

Main Configuration File

The main configuration file (simple-sftpd.conf) supports both INI and JSON formats. Here's an example INI configuration:

# Global server settings
server_name = "Simple-Secure FTP Daemon"
server_version = "0.1.0"
enable_ssl = true
enable_virtual_hosts = true

# SSL Configuration
[ssl]
enabled = true
certificate_file = "/etc/simple-sftpd/ssl/server.crt"
private_key_file = "/etc/simple-sftpd/ssl/server.key"

# Connection settings
[connection]
bind_address = "0.0.0.0"
bind_port = 21
max_connections = 100

# Virtual hosts
[virtual_hosts.default]
hostname = "default"
document_root = "/var/ftp"
enabled = true

# Users
[users.admin]
username = "admin"
password_hash = "$2y$10$hashed_password"
home_directory = "/var/ftp/admin"
permissions = ["READ", "WRITE", "LIST", "UPLOAD", "DOWNLOAD"]

User Management

Adding Users

# Add a new user
sudo simple-sftpd user add \
  --username john \
  --password secret \
  --home /var/ftp/john \
  --permissions READ,WRITE,LIST,UPLOAD,DOWNLOAD

# Add anonymous user
sudo simple-sftpd user add \
  --username anonymous \
  --home /var/ftp/public \
  --anonymous \
  --permissions READ,LIST,DOWNLOAD

User Permissions

Available permissions:

READ: Read files and directories
WRITE: Write/create files and directories
DELETE: Delete files and directories
RENAME: Rename files and directories
MKDIR: Create directories
RMDIR: Remove directories
LIST: List directory contents
UPLOAD: Upload files
DOWNLOAD: Download files
APPEND: Append to files
ADMIN: Administrative operations

Virtual Hosts

Adding Virtual Hosts

# Add a new virtual host
sudo simple-sftpd virtual add \
  --hostname ftp.example.com \
  --root /var/ftp/example \
  --ssl \
  --certificate /etc/ssl/certs/example.com.crt \
  --private-key /etc/ssl/private/example.com.key

Virtual Host Configuration

Each virtual host can have:

Separate document root
Individual SSL certificates
Custom security settings
User access restrictions
Transfer rate limits

SSL/TLS Configuration

Generating Self-Signed Certificates

# Generate certificate for a domain
sudo simple-sftpd ssl generate \
  --hostname ftp.example.com \
  --country US \
  --state California \
  --city San Francisco \
  --organization "Example Corp" \
  --email admin@example.com

Installing Certificates

# Install existing certificates
sudo simple-sftpd ssl install \
  --hostname ftp.example.com \
  --certificate /path/to/certificate.crt \
  --private-key /path/to/private.key \
  --ca-certificate /path/to/ca.crt

Command Line Interface

Server Commands

# Start the server
simple-sftpd start [--config FILE] [--daemon] [--foreground]

# Stop the server
simple-sftpd stop

# Restart the server
simple-sftpd restart

# Show server status
simple-sftpd status

# Reload configuration
simple-sftpd reload

User Management Commands

# List all users
simple-sftpd user list

# Add user
simple-sftpd user add --username NAME --password PASS --home DIR

# Remove user
simple-sftpd user remove --username NAME

# Modify user
simple-sftpd user modify --username NAME --permissions READ,WRITE

# Change password
simple-sftpd user password --username NAME --password NEW_PASS

Virtual Host Commands

# List virtual hosts
simple-sftpd virtual list

# Add virtual host
simple-sftpd virtual add --hostname DOMAIN --root DIR

# Remove virtual host
simple-sftpd virtual remove --hostname DOMAIN

# Enable/disable virtual host
simple-sftpd virtual enable --hostname DOMAIN
simple-sftpd virtual disable --hostname DOMAIN

SSL Management Commands

# Generate certificate
simple-sftpd ssl generate --hostname DOMAIN

# Install certificate
simple-sftpd ssl install --hostname DOMAIN --cert FILE --key FILE

# Show SSL status
simple-sftpd ssl status

# Renew certificate
simple-sftpd ssl renew --hostname DOMAIN

Development

Building from Source

# Clone and setup
git clone https://github.com/simple-sftpd/simple-sftpd.git
cd simple-sftpd

# Install dependencies
make install-dev

# Build options
make debug      # Debug build
make release    # Release build
make test       # Run tests
make clean      # Clean build artifacts

# Package creation
make package    # Create packages for current platform

Project Structure

simple-sftpd/
├── include/simple-sftpd/     # Header files
│   ├── ftp_server.hpp       # Main server class
│   ├── ftp_connection.hpp   # Connection handling
│   ├── ftp_user.hpp         # User management
│   ├── ftp_virtual_host.hpp # Virtual host support
│   ├── ftp_server_config.hpp # Configuration
│   ├── logger.hpp           # Logging system
│   └── platform.hpp         # Platform abstraction
├── src/                     # Source files
│   ├── core/               # Core implementation
│   ├── utils/              # Utility functions
│   └── main.cpp            # Main application
├── config/                  # Configuration files
├── tools/                   # Management tools
├── docs/                    # Documentation
├── scripts/                 # Build and deployment scripts
├── deployment/              # Deployment configurations
│   └── examples/
│       └── docker/          # Docker deployment examples
├── Dockerfile              # Multi-stage Docker build
├── docker-compose.yml      # Docker Compose orchestration
├── .dockerignore           # Docker build context optimization
├── CMakeLists.txt          # CMake build configuration
└── Makefile                # Make build system

🐳 Docker Infrastructure

simple-sftpd includes comprehensive Docker support for development, testing, and production deployment:

Docker Features

Multi-stage builds for different Linux distributions (Ubuntu, CentOS, Alpine)
Multi-architecture support (x86_64, ARM64, ARMv7)
Development environment with debugging tools and live code mounting
Production-ready runtime with minimal footprint and security hardening
Health checks and monitoring capabilities
Volume mounts for configuration, logs, and FTP data

Quick Docker Commands

# Development environment
docker-compose --profile dev up -d

# Production deployment
docker-compose --profile runtime up -d

# Build for all platforms
./scripts/build-docker.sh -d all

# Deploy with custom configuration
./scripts/deploy-docker.sh -p runtime -c ./config -l ./logs -d ./data

Docker Ports

21/tcp - FTP control port
990/tcp - FTPS control port (SSL/TLS)
1024-65535/tcp - Passive mode data ports

For complete Docker documentation, see Docker Deployment Guide.

Contributing

Fork the repository
Create a feature branch
Make your changes
Add tests for new functionality
Ensure all tests pass
Submit a pull request

Testing

# Run all tests
make test

# Run specific test suites
cd build && ctest -R "unit_tests"
cd build && ctest -R "integration_tests"

# Run with coverage (Linux only)
make coverage

# Run with memory checking (Linux only)
make memcheck

Troubleshooting

Common Issues

Server Won't Start

Check configuration:

simple-sftpd --test-config --config /etc/simple-sftpd/simple-sftpd.conf

Check permissions:

sudo chown -R ftp:ftp /var/ftp
sudo chmod 755 /var/ftp

Check ports:

sudo netstat -tlnp | grep :21

SSL Connection Issues

Verify certificate files:

openssl x509 -in /etc/simple-sftpd/ssl/server.crt -text -noout

Check certificate permissions:

sudo chmod 600 /etc/simple-sftpd/ssl/server.key
sudo chown ftp:ftp /etc/simple-sftpd/ssl/server.key

Performance Issues

Check system resources:

top
iostat
netstat -i

Adjust configuration:

[connection]
max_connections = 50
thread_pool_size = 4

[transfer]
buffer_size = 16384
use_sendfile = true

Log Files

Main log: /var/log/simple-sftpd/simple-sftpd.log
Access log: /var/log/simple-sftpd/access.log
Error log: /var/log/simple-sftpd/error.log

Debug Mode

Enable debug logging:

[logging]
log_level = "DEBUG"
log_commands = true
log_transfers = true

# Development settings
debug_mode = true
verbose_logging = true
trace_commands = true

Security Considerations

Production Deployment

Use strong SSL certificates
Enable chroot for users
Drop privileges to non-root user
Implement rate limiting
Restrict allowed commands
Use firewall rules
Regular security updates

Network Security

# Firewall rules (iptables)
sudo iptables -A INPUT -p tcp --dport 21 -j ACCEPT
sudo iptables -A INPUT -p tcp --dport 1024:65535 -j ACCEPT

# Or with ufw (Ubuntu)
sudo ufw allow 21/tcp
sudo ufw allow 1024:65535/tcp

User Security

Strong password policies
Limited permissions
Path restrictions
Connection limits
Session timeouts

Performance Tuning

System Tuning

# Increase file descriptor limits
echo "* soft nofile 65536" >> /etc/security/limits.conf
echo "* hard nofile 65536" >> /etc/security/limits.conf

# Kernel parameters
echo "net.core.somaxconn = 65536" >> /etc/sysctl.conf
echo "net.ipv4.tcp_max_syn_backlog = 65536" >> /etc/sysctl.conf
sysctl -p

Application Tuning

[connection]
max_connections = 200
backlog = 100
keep_alive = true
tcp_nodelay = true

[transfer]
buffer_size = 32768
use_sendfile = true
use_mmap = true

# Performance settings
thread_pool_size = 16
enable_compression = true
cache_size = 100MB

Monitoring and Metrics

Built-in Monitoring

# Show server statistics
simple-sftpd status

# Show performance metrics
simple-sftpd metrics

# Show connection information
simple-sftpd connections

External Monitoring

Prometheus: Metrics endpoint at /metrics
Grafana: Dashboard templates included
Log aggregation: Structured logging support
Health checks: HTTP health endpoint

License

This project is licensed under the Apache License, Version 2.0 - see the LICENSE file for details.

Support

Documentation: docs/
Issues: GitHub Issues
Discussions: GitHub Discussions
Email: SimpleDaemons

Acknowledgments

OpenSSL: SSL/TLS implementation
jsoncpp: JSON parsing library
CMake: Build system
FTP RFC 959: Protocol specification

Changelog

v0.1.0 (Current - 85% Complete)

✅ Core FTP server functionality with file transfers
✅ Passive mode data connections
✅ User authentication and management
✅ CLI management interface (start, stop, restart, status, reload, test, user, virtual, ssl)
✅ Path validation and security
✅ Basic permission system
✅ Comprehensive logging (STANDARD, JSON, EXTENDED formats)
✅ Test suite (46 tests passing)
✅ Multi-platform support
✅ Comprehensive configuration system
🔄 SSL/TLS support (v0.2.0)
🔄 Virtual hosting (v0.3.0)

Name		Name	Last commit message	Last commit date
Latest commit History 91 Commits
automation		automation
config		config
deployment		deployment
docs		docs
etc		etc
include/simple-sftpd		include/simple-sftpd
packaging		packaging
project		project
scripts		scripts
src		src
tests		tests
tools		tools
.dockerignore		.dockerignore
.gitignore		.gitignore
.travis.yml		.travis.yml
CHANGELOG.md		CHANGELOG.md
CMakeLists.txt		CMakeLists.txt
Dockerfile		Dockerfile
Jenkinsfile		Jenkinsfile
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
REFACTORING_PLAN.md		REFACTORING_PLAN.md
ROADMAP.md		ROADMAP.md
docker-compose.yml		docker-compose.yml
simple-sftpd.code-workspace		simple-sftpd.code-workspace

License

SimpleDaemons/simple-sftpd

Folders and files

Latest commit

History

Repository files navigation

Simple Secure FTP Daemon (simple-sftpd)

Features

Core FTP Functionality

Security Features

Virtual Hosting

User Management

Performance & Monitoring

Platform Support

Quick Start

🐳 Docker (Recommended)

Traditional Installation

Prerequisites

From Source

From Packages

Configuration

Running the Server

Basic Usage

Service Management

Configuration

Main Configuration File

User Management

Adding Users

User Permissions

Virtual Hosts

Adding Virtual Hosts

Virtual Host Configuration

SSL/TLS Configuration

Generating Self-Signed Certificates

Installing Certificates

Command Line Interface

Server Commands

User Management Commands

Virtual Host Commands

SSL Management Commands

Development

Building from Source

Project Structure

🐳 Docker Infrastructure

Docker Features

Quick Docker Commands

Docker Ports

Contributing

Testing

Troubleshooting

Common Issues

Server Won't Start

SSL Connection Issues

Performance Issues

Log Files

Debug Mode

Security Considerations

Production Deployment

Network Security

User Security

Performance Tuning

System Tuning

Application Tuning

Monitoring and Metrics

Built-in Monitoring

External Monitoring

License

Support

Acknowledgments

Changelog

v0.1.0 (Current - 85% Complete)

About

Topics

Resources

License

Uh oh!

Stars

Watchers

Forks

Releases 1

Packages