ed2kNET (v0.4.4.5)

ed2kNET is an implementation of the eDonkey2000 (ed2k) protocol written in F#. The project includes both server and client protocol specifications and allows for the operation of a basic ed2k server.

Features

• ed2k Server Protocol: Implementation of core functionalities for an eDonkey server.
• Search Functionality: Support for ed2k search queries with various filters (filename, size, type, etc.).
• Client Interaction: Basic support for client handshakes and reachability checks.
• Obfuscation support (TCP/UDP): Includes implementations for RC4 and protocol obfuscation for both TCP and UDP.
• Modern Protocol Support: Support for Large Files (>4GB), Unicode, and NewTags.
• Server protcol Support: First open-source eServer able to exchange ServerLists with Lugdunum
• Multi-Socket UDP: Separate UDP sockets for IPv4 and IPv6 for better connectivity.
• Configurable: Simple configuration via a config.json file.
• Testing IPv6 Support: Client's may connect to both IPv6 or IPv4 stack
• Real Aead Encryption support: Server supports both AEAD (AES256-GCM / ChaCha20-Poly1305) and legacy obfuscation.
• Security: X25519 (Elliptic Curve) key exchange for secure communication.
• File filtering (RegEx support): Support for filtering files using regular expressions.
• Database Storage: Recorded files are stored in Postgres or SQLite database
• Metrics / Prometheus dotNET support: Support for metrics and Prometheus integration.

TODOs

• blacklisting
• ...

Prerequisites

• .NET 9.0 SDK or newer.
• F# (installed with the .NET SDK).
• LibSodium (installed libsodium libraries)
• SQLite3 (installed SQLite3 libraries) [optional]
• Note: single executable bundles libraries

Installation & Execution

1. Clone or download the repository.
2. Navigate to the project directory.
3. Restore dependencies:

   dotnet restore
   

4. Build the project:

   dotnet build
   

5. Start the server:

   dotnet run
   

Configuration

The server settings can be adjusted in the config.json file:

{
  "ServerConfig": {
    "PublicIP": "",
    "ListenAddress": "0.0.0.0",
    "ListenPort": 4232,
    "Ipv6Enable": false,
    "Ipv6ListenAddress": "[::]",
    "Ipv6ListenPort": 4235,
    "MaxFiles": 6000000,
    "MaxClients": 60000,
    "ObsUdpKey": 0,
    "LogLevel": 2,
    "ConsoleShowStats": true,
    "WelcomeMessage": "-= This is ed2kNET - dotNET Ed2k/eServer =-\r\nExperimental Ed2k/eServer reimplementation\r\n",
    "ServerName": "Hydra ed2kNET Server",
    "ServerDescription": "Experimental Ed2k Server",
    "FileFilterPath": "filefilter.json",
    "MetricsEnabled": true,
    "MetricsPort": 9351,
    "MqttEnabled": false,
    "MqttHost": "",
    "MqttPort": 1883,
    "MqttUsername": "",
    "MqttPassword": "",
    "MqttTopicPrefix": "ed2k/server",
    "SeedIP": "",
    "SeedPort": 0,
    "GlobalUdpLimit": 3000,
    "GlobalUdpInterval": 30,
    "PostgresDB": false,
    "DbConnectionString": "Host=127.0.0.1;Port=5432;Username=ed2k;Password=password;Database=ed2k;"
  }
}

• PublicIP: Required in Docker environments (must be set to public Server IP)
• ListenAddress: The IPv4 address the server listens on. (should be default in Docker)
• ListenPort: The port for inbound TCP connections. (UDP client port is always TCP+4)
• Ipv6Enable: Enable IPv6 ability in dual-stack configurations
• Ipv6ListenAddress: The IPv6 address the server listens on. (should be default in Docker)
• MaxFiles / MaxClients: Limits for server operation.
• ObsUdpKey: Stub entry (is always random on next restart)
• LogLevel: Verbosity of the logs (0-3).
• ConsoleShowStats: Print [STAT] output on console every 10s
• WelcomeMessage: Public welcome message the ed2k client will see
• ServerName: Official server name
• ServerDescription: Public server description
• FileFilterPath: defines a filter for files (in RegEx statements) which rejects shared files if matched any rule
• MetricsEnabled: Enable Prometheus metrics.
• MetricsPort: Metrics HTTP port (unencrypted, will not publish client related information)
• MqttEnabled: Enable MQTT reporting. (WIP)
• MqttPort: MQTT port to send requests to
• MqttUsername: MQTT username (empty on default)
• MqttPasssword: MQTT password
• MqttTopicPrefix: MQTT topic, used to publish server information
• SeedIP: Seed eServer used to request ServerList (Lugdunum)
• SeedPort: Seed eServer TCP port
• GlobalUdpLimit: Global limit for UDP packets processed within the interval
• GlobalUdpInterval: Interval in seconds for the global UDP rate limit
• PostgresDB: Enable Postgres usage, requires provided DbConnectionString
• DbConnectionString: DSN in order to connect to remote postgres

Project Structure

• Logging.fs: Flexible logging system with support for rotation.
• Utility.fs: General purpose utility functions for byte and span manipulation.
• BinaryWrite.fs: Low-level helpers for binary data serialization.
• Interfaces.fs: Common abstractions for network communication (INetwork, IBuffered).
• ed2kSearch.fs: Implementation of the search engine and query filtering.
• ed2k.fs: Core eDonkey2000 protocol specifications, opcodes, and data structures.
• ed2kClient.fs: Communication logic for client-side interactions.
• Config.fs: Configuration loader and management for config.json.
• Stats.fs: Collection of server metrics and performance statistics.
• Mqtt.fs: MQTT integration for real-time server monitoring and reporting.
• RC4.fs: Implementation of the RC4 stream cipher for legacy obfuscation.
• ObfuscationUDP.fs / ObfuscationTCP.fs: Legacy protocol obfuscation support.
• CryptoExtended.fs: Modern cryptography (X25519 key exchange and AEAD encryption).
• EncryptionUDP.fs / EncryptionTCP.fs: AEAD-based secure communication layers.
• FileFilter.fs: Regular expression-based filtering system for shared files.
• FileRegister.fs: Central registry for shared files and source management.
• ed2kServer.fs: Logic for handling client requests and generating server responses.
• ServerProto.fs: Server-to-server protocol implementation (e.g., ServerList exchange with Lugdunum).
• ServerTasks.fs: Management of background tasks for TCP/UDP listeners and status updates.
• Program.fs: Entry point and main server orchestration logic.

Docker image usage

Please keep in mind that for Server exchange protocol support to work, the eServer requires multiple UDP inbound/outbound ports. The user cannot change these!

In order these are:

• TCP + 4 UDP port for client communication
• TCP + 12 UDP port for Obfuscation/Server Obs Ping
• TCP + 14 UDP port for obfuscated server communication

Because of this you must also set a PublicIP in the config.json (see docker-compose.yml)

License

This project is licensed under the GPLv3 license. For more information, see the LICENSE file.

Author

Copyright (C) 2019-2025 georg@bege.email See Telegram channel: HydraP2P / https://t.me/+krHfzWREKcc3NjVi