Simple RSync Daemon (simple-rsyncd)

A lightweight rsync-style daemon in C++ for modern server environments.

Release status: v0.3.1 Beta — Installers and core file operations are tested (ctest 5/5 suites). This is not a drop-in replacement for native rsyncd; TLS, Prometheus, OAuth2, and full rsync(1) wire compatibility are planned for later releases. See project/PRODUCTION_GATE.md.

🚀 Features

Implemented (v0.3.1)

Multi-platform packaging: Linux (DEB/RPM), FreeBSD (PKG), macOS (PKG/DMG)
Module system: Path isolation, read-only/list/delete/overwrite permissions, include/exclude patterns
File operations: Upload, download, delete, directory list/create/delete with path traversal protection
Custom protocol: LIST / GET / PUT / DELETE / STAT with key=value arguments
Authentication: Password file auth with SHA-256 hashing, allow/deny user lists
Configuration: INI format (JSON/YAML parsers present; verify your format before relying on it)
Logging: Structured logging with rotation support
Tests: Google Test unit and integration suites (all passing)

Planned (not yet production-ready)

SSL/TLS encryption — interface exists; handshake not fully implemented
OAuth2, Prometheus, rate limiting enforcement — config stubs only
Native rsync client compatibility — use the custom protocol or bundled test client for now
YAML hot-reload — partial; treat as experimental

📋 Requirements

C++17 compatible compiler (GCC 7+, Clang 5+, MSVC 2017+)
CMake 3.16+
OpenSSL 1.1.1+
jsoncpp (for JSON configuration parsing)
yaml-cpp (optional, for YAML configuration parsing)
Linux: glibc 2.17+, pthread, rt
macOS: macOS 12.0+ (Monterey)
Windows: Windows 10+ with Visual Studio 2017+

🛠️ Installation

Quick Start

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

# Build the project
mkdir build && cd build
cmake ..
make -j$(nproc)

# Install
sudo make install

Dependencies

Ubuntu/Debian

sudo apt-get update
sudo apt-get install -y build-essential cmake libssl-dev libjsoncpp-dev libyaml-cpp-dev

CentOS/RHEL/Fedora

sudo yum install -y gcc-c++ cmake openssl-devel jsoncpp-devel yaml-cpp-devel
# or for newer versions:
sudo dnf install -y gcc-c++ cmake openssl-devel jsoncpp-devel yaml-cpp-devel

macOS

brew install openssl jsoncpp yaml-cpp cmake

# If you encounter permission issues during installation, run:
./scripts/fix-macos-permissions.sh

Windows

Install Visual Studio 2017+ with C++ support
Install CMake and OpenSSL
Use vcpkg for jsoncpp: vcpkg install jsoncpp

🚀 Usage

Basic Commands

# Start the daemon
simple-rsyncd start --config /etc/simple-rsyncd/rsyncd.conf

# Start as daemon
simple-rsyncd start --daemon --config /etc/simple-rsyncd/rsyncd.conf

# Check status
simple-rsyncd status

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

# Reload configuration
simple-rsyncd reload

# Stop daemon
simple-rsyncd stop

# Restart daemon
simple-rsyncd restart

Configuration

The daemon uses a hierarchical configuration system with support for:

Global settings: Network, SSL, authentication, logging
Module definitions: Path-based access control and permissions
Configuration formats: INI, JSON, and YAML (v0.3.0)
Environment variables: Variable substitution in config files (v0.3.0)
Hot-reloading: Automatic configuration reload on file changes (v0.3.0)
Configuration validation: Comprehensive validation with detailed errors

Example configurations:

INI Format:

[global]
bind_address = 0.0.0.0
bind_port = 873
ssl_enabled = true
auth_enabled = true

[module:backup]
path = /var/backup
comment = Backup storage
read_only = false
list = true
delete = true
overwrite = true

YAML Format:

global:
  bind_address: 0.0.0.0
  bind_port: 873
  ssl:
    enabled: true
  auth:
    enabled: true

modules:
  backup:
    path: /var/backup
    comment: Backup storage
    read_only: false
    list: true
    allow_delete: true
    overwrite: true

JSON Format:

{
  "global": {
    "bind_address": "0.0.0.0",
    "bind_port": 873
  },
  "ssl": {
    "enabled": true
  },
  "auth": {
    "enabled": true
  },
  "modules": {
    "backup": {
      "path": "/var/backup",
      "comment": "Backup storage",
      "read_only": false,
      "list": true,
      "allow_delete": true,
      "overwrite": true
    }
  }
}

Client Usage

simple-rsyncd uses a simplified custom protocol (not full native rsync wire format). For beta testing, use the daemon’s protocol commands or the project test client.

# Example protocol commands (over TCP to bind_port, default 873)
# LIST <module> <path> [key=value ...]
# GET  <module> <path>
# PUT  <module> <path>
# DELETE <module> <path> [recursive=true]

# List available modules (after connecting and authenticating if enabled)
# See docs/ and src/tests/ for worked examples.

Native rsync rsync://… compatibility is not guaranteed in v0.3.1; see the v0.5.0 client matrix in project/PRODUCTION_GATE.md.

🏗️ Architecture

Core Components

RSyncDaemon: Main server class managing connections and modules
Configuration: Hierarchical configuration management with validation
Module: Abstract interface for file system operations
RSyncSession: Individual client connection handling
SSLContext: SSL/TLS encryption management
Logger: Comprehensive logging system

Module System

Modules provide:

Path isolation: Each module has its own root directory
Permission control: Read-only, list, delete, and overwrite permissions
Pattern filtering: Include/exclude patterns for files
Script hooks: Pre/post transfer, delete, and list scripts
Environment variables: Custom configuration per module

Security Features

SSL/TLS encryption: Secure file transfers
Authentication: Multiple authentication methods
Access control: IP and network restrictions
Path validation: Prevention of directory traversal attacks
Privilege dropping: Running with minimal permissions
Chroot support: File system isolation

🔧 Configuration

Configuration Files

Main config: /etc/simple-rsyncd/rsyncd.conf
Module configs: /etc/simple-rsyncd/modules.d/
User database: /etc/simple-rsyncd/users
SSL certificates: /etc/simple-rsyncd/ssl/

Environment Variables

# Override configuration file location
export SIMPLE_RSYNCD_CONFIG=/path/to/config

# Enable debug mode
export SIMPLE_RSYNCD_DEBUG=1

# Set log level
export SIMPLE_RSYNCD_LOG_LEVEL=debug

Configuration Inheritance

# Base configuration
[global]
ssl_enabled = true
auth_enabled = true

# Production override
[global:production]
ssl_enabled = true
auth_enabled = true
ssl_require_client_cert = true

# Development override
[global:development]
ssl_enabled = false
auth_enabled = false

📊 Monitoring

Metrics

Connection statistics: Active connections, total connections
Transfer statistics: Bytes transferred, files transferred
Performance metrics: Transfer rates, response times
Error rates: Failed transfers, authentication failures

Health Checks

Service health: Daemon status and responsiveness
Module health: Module availability and permissions
Resource usage: Memory, CPU, and disk usage
SSL certificate: Certificate expiration and validity

Prometheus Integration

# prometheus.yml
scrape_configs:
  - job_name: 'simple-rsyncd'
    static_configs:
      - targets: ['localhost:9090']
    metrics_path: '/metrics'

🔒 Security

SSL/TLS Configuration

[global]
ssl_enabled = true
ssl_certificate_file = /etc/simple-rsyncd/ssl/server.crt
ssl_private_key_file = /etc/simple-rsyncd/ssl/server.key
ssl_ca_file = /etc/simple-rsyncd/ssl/ca.crt
ssl_cipher_suite = ECDHE-RSA-AES256-GCM-SHA384
ssl_tls_version = 1.2

Authentication (v0.3.0 Enhanced)

[global]
auth_enabled = true
auth_method = password
auth_password_file = /etc/simple-rsyncd/users
auth_realm = simple-rsyncd

# Password policies (v0.3.0)
password_policy_min_length = 8
password_policy_require_uppercase = true
password_policy_require_lowercase = true
password_policy_require_digits = true
password_policy_expiration_hours = 2160  # 90 days

# Session management (v0.3.0)
session_timeout = 3600
enable_session_management = true

Password Security:

Passwords are automatically hashed using SHA-256 with salt
Supports both plain text (backward compatible) and pre-hashed passwords
Password policies enforce complexity requirements
Password expiration and account lockout support
User database with CRUD operations

Access Control

[global]
access_enabled = true
access_allowed_hosts = 127.0.0.1, 192.168.1.0/24
access_allowed_networks = 10.0.0.0/8
access_denied_hosts = 192.168.1.100

🚀 Performance

Optimization Features

Connection pooling: Efficient connection management
Buffer optimization: Configurable buffer sizes
Compression: Built-in compression support
Pipelining: Parallel transfer operations
Checksum verification: Fast file integrity checking

Benchmarking

# Test transfer performance
rsync -avz --progress /large/directory/ rsync://server/module/

# Test concurrent connections
for i in {1..10}; do
  rsync -avz /test/dir/ rsync://server/module/ &
done
wait

🐳 Docker Support

Quick Start

# Build image
docker build -t simple-rsyncd .

# Run container
docker run -d \
  --name simple-rsyncd \
  -p 873:873 \
  -v /path/to/config:/etc/simple-rsyncd \
  -v /path/to/data:/var/lib/simple-rsyncd \
  simple-rsyncd

Docker Compose

version: '3.8'
services:
  simple-rsyncd:
    build: .
    ports:
      - "873:873"
    volumes:
      - ./config:/etc/simple-rsyncd
      - ./data:/var/lib/simple-rsyncd
    environment:
      - SIMPLE_RSYNCD_CONFIG=/etc/simple-rsyncd/rsyncd.conf

🔧 Development

Building from Source

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

# Create build directory
mkdir build && cd build

# Configure with CMake
cmake .. \
  -DCMAKE_BUILD_TYPE=Release \
  -DBUILD_TESTS=ON \
  -DBUILD_EXAMPLES=ON

# Build
make -j$(nproc)

# Run tests
make test

# Install
sudo make install

Development Dependencies

# Ubuntu/Debian
sudo apt-get install -y \
  build-essential cmake \
  libssl-dev libjsoncpp-dev \
  clang-format cppcheck \
  valgrind gdb

# macOS
brew install \
  cmake openssl jsoncpp \
  clang-format cppcheck \
  valgrind lldb

Code Style

C++17 standard
Clang-format for code formatting
Cppcheck for static analysis
Valgrind for memory checking
Google Test for unit testing

📚 Documentation

Installation Guide: Platform-specific installation instructions
User Guide: Complete usage documentation
Configuration Guide: Configuration reference (v0.3.0: JSON format, env vars, hot-reload)
Error Handling Guide: Comprehensive error handling system (v0.3.0)
Development Guide: Contributing and development
API Reference: Developer API documentation
Troubleshooting Guide: Common issues and solutions

📖 Start with the Installation Guide for first-time setup

🆕 v0.3.0 Features:

Password hashing and policies
User database and session management
Configuration hot-reload
Environment variable substitution
Enhanced logging with rotation
Comprehensive error handling

🤝 Contributing

We welcome contributions! Please see our Contributing Guide for details.

Development Setup

# Fork and clone
git clone https://github.com/your-username/simple-rsyncd.git
cd simple-rsyncd

# Create feature branch
git checkout -b feature/amazing-feature

# Make changes and test
make test

# Commit and push
git commit -m "Add amazing feature"
git push origin feature/amazing-feature

# Create pull request

📄 License

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

🙏 Acknowledgments

rsync project for the protocol specification
OpenSSL project for cryptographic libraries
jsoncpp project for JSON parsing
CMake project for build system
All contributors who have helped improve this project

📞 Support

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

🔄 Changelog

See CHANGELOG.md for a complete list of changes.

Simple RSync Daemon - Secure, fast, and reliable file synchronization for modern servers.

Name		Name	Last commit message	Last commit date
Latest commit History 109 Commits
automation		automation
cmake		cmake
config		config
deployment		deployment
docs		docs
include/simple-rsyncd		include/simple-rsyncd
packaging		packaging
project		project
scripts		scripts
src		src
.dockerignore		.dockerignore
.gitignore		.gitignore
CMakeLists.txt		CMakeLists.txt
Dockerfile		Dockerfile
GNUmakefile		GNUmakefile
Jenkinsfile		Jenkinsfile
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
ROADMAP.md		ROADMAP.md
docker-compose.yml		docker-compose.yml
simple-rsyncd.code-workspace		simple-rsyncd.code-workspace

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Simple RSync Daemon (simple-rsyncd)

🚀 Features

Implemented (v0.3.1)

Planned (not yet production-ready)

📋 Requirements

🛠️ Installation

Quick Start

Dependencies

Ubuntu/Debian

CentOS/RHEL/Fedora

macOS

Windows

🚀 Usage

Basic Commands

Configuration

Client Usage

🏗️ Architecture

Core Components

Module System

Security Features

🔧 Configuration

Configuration Files

Environment Variables

Configuration Inheritance

📊 Monitoring

Metrics

Health Checks

Prometheus Integration

🔒 Security

SSL/TLS Configuration

Authentication (v0.3.0 Enhanced)

Access Control

🚀 Performance

Optimization Features

Benchmarking

🐳 Docker Support

Quick Start

Docker Compose

🔧 Development

Building from Source

Development Dependencies

Code Style

📚 Documentation

🤝 Contributing

Development Setup

📄 License

🙏 Acknowledgments

📞 Support

🔄 Changelog

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