Distributed Hash Table (DHT) Implementation

A Python-based Distributed Hash Table implementation that allows nodes to connect across different networks using IP addresses. This implementation supports key-value storage and retrieval across multiple nodes.

Features

• Cross-network node communication
• Key-value storage and retrieval
• Automatic node discovery
• Data replication between nodes
• Data synchronization when joining the network
• Reliable bootstrapping with retry mechanism
• Simple CLI interface
• Public IP detection
• Local network support
• Python library interface for programmatic use

Installation

From PyPI (Recommended)

pip install simpledht

From Source

1. Clone the repository:

git clone https://github.com/dhruvldrp9/SimpleDHT
cd SimpleDHT

2. Create and activate a virtual environment:

python -m venv env
source env/bin/activate  # On Windows: env\Scripts\activate

3. Install the package in development mode:

pip install -e .

Usage

As a Python Library

The package can be used programmatically in your Python code:

from simpledht import DHTNode

# Create and start a node
node = DHTNode(host='0.0.0.0', port=5000)
node.start()

# Store data
node.put('mykey', 'myvalue')

# Retrieve data
value = node.get('mykey')

# Connect to another node
node.bootstrap('other_node_ip:5000')

# Stop the node when done
node.stop()

See the examples/ directory for more detailed usage examples:

• basic_usage.py: Simple example of creating and connecting nodes
• distributed_storage.py: Advanced example showing distributed storage with multiple nodes

Command Line Interface

Starting a Node

To start a new DHT node:

python -m simpledht.cli start --host 0.0.0.0 --port 5000

To start a node and connect to existing nodes:

python -m simpledht.cli start --host 0.0.0.0 --port 5001 --bootstrap "PUBLIC_IP:5000"

Storing Data

To store a key-value pair:

python -m simpledht.cli put --host PUBLIC_IP --port 5000 mykey "my value"

Retrieving Data

python -m simpledht.cli get --host PUBLIC_IP --port 5000 mykey

Cross-Network Example

1. Start Node 1 (First network):

python -m simpledht.cli start --host 0.0.0.0 --port 5000

2. Start Node 2 (Second network):

python -m simpledht.cli start --host 0.0.0.0 --port 5000 --bootstrap "NODE1_PUBLIC_IP:5000"

3. Store and retrieve data:

# Store on Node 1
python -m simpledht.cli put --host NODE1_PUBLIC_IP --port 5000 test_key "test_value"

# Retrieve from Node 2
python -m simpledht.cli get --host NODE2_PUBLIC_IP --port 5000 test_key

Network Configuration

Firewall Setup

Ensure the UDP port (default: 5000) is open in your firewall:

# For UFW (Ubuntu)
sudo ufw allow 5000/udp

# For iptables
sudo iptables -A INPUT -p udp --dport 5000 -j ACCEPT

Port Forwarding

If your node is behind a NAT router:

1. Access your router's admin interface
2. Set up port forwarding for UDP port 5000
3. Forward to your node's local IP address

New Features in Version 0.1.3

• Improved Bootstrap Mechanism: Added retry logic for more reliable connections across networks
• Data Synchronization: Nodes automatically sync data when joining the network
• Enhanced Error Handling: Better handling of network timeouts and connection issues
• Full Data Replication: All nodes maintain a complete copy of the data for redundancy
• Alternative Command Method: Added support for running via python -m simpledht.cli

Troubleshooting

Common Issues

1. Connection Timeout

   • Check if the target node is running
   • Verify firewall settings
   • Ensure port forwarding is configured correctly
   • Try increasing the timeout: --timeout 10

2. Address Already in Use

   • The port is already being used by another process
   • Try a different port number
   • Check running processes: netstat -tuln | grep 5000

3. No Response from Node

   • Verify the node is running
   • Check network connectivity: ping NODE_IP
   • Test port connectivity: nc -vzu NODE_IP 5000

Error Messages

• Failed to bootstrap with IP:PORT: Invalid bootstrap node format
• No response received: Node is not responding
• Address already in use: Port conflict
• Failed to get public IP: Network connectivity issue
• Connection attempt X/3 timed out, retrying...: Network latency or connectivity issues
• simpledht: command not found: The command-line tool is not in your PATH. Use the Python module directly: python -m simpledht.cli

Architecture

The DHT implementation uses:

• UDP sockets for communication
• SHA-256 for node ID generation
• Automatic public IP detection
• Data replication between nodes
• Bootstrap nodes for network discovery
• Retry mechanism for reliable connections

Security Considerations

• This is a basic implementation and should not be used in production without additional security measures
• Consider adding:
  • Encryption for data in transit
  • Authentication for node joining
  • Rate limiting to prevent abuse
  • Input validation

Contributing

1. Fork the repository
2. Create a feature branch
3. Commit your changes
4. Push to the branch
5. Create a Pull Request

License

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