VikingMUD FTP Daemon

A custom FTP server designed specifically for VikingMUD, providing secure file access with native integration into the MUD's player authentication and hiearchical authorization system. This daemon understands LPC serialized object format and directly interfaces with the MUD's character database and access control trees.

Installation

Building

Requires Go 1.22 or higher. Build using the provided Makefile:

make build   # Creates vkftpd binary with version information
./vkftpd --version  # Verify build

Or build manually with go build.

Running

To start the server with your configuration:

./vkftpd --config config.json

Configuration

Create a configuration file in JSON format. Example:

{
    "listen_addr": "0.0.0.0",
    "port": 2121,
    "ftp_root_dir": "/mud/lib",
    "character_dir_path": "/mud/lib/characters",
    "access_file_path": "/mud/lib/dgd/sys/data/access.o",
    "home_pattern": "players/%s",
    "tls_cert_file": "/path/to/cert.pem",
    "tls_key_file": "/path/to/key.pem",
    "pasv_port_range": [2122, 2150],
    "pasv_address": "your.public.ip.address",
    "pasv_ip_verify": true,
    "max_connections": 10,
    "idle_timeout": 300,
    "character_cache_time": 60,
    "access_cache_time": 60,
    "access_log_path": "/mud/lib/log/vkftpd-access.log",
    "app_log_path": "/mud/lib/log/vkftpd-app.log",
    "log_level": "info",
    "max_log_size": 1000000,
    "log_verify_interval": 45,
    "status_dir": "/mud/lib/sys/ftp"
}

Network Settings

• listen_addr: Address to listen on (e.g., "0.0.0.0" for all interfaces)
• port: Port to listen on (default: 2121)
• pasv_port_range: Range of ports for passive mode (default: [50000, 50100])
• pasv_address: Public IP address to advertise for passive mode connections (optional)
• pasv_ip_verify: Whether to verify data connection IP matches control IP (optional, default: false)
• max_connections: Maximum concurrent connections (default: 10)
• idle_timeout: Connection idle timeout in seconds (default: 300)

File System Configuration

• ftp_root_dir: Root directory for FTP access (required)
• character_dir_path: Path to character files directory (required)
• access_file_path: Path to the MUD's access.o file (required)
• home_pattern: Pattern for user home directories (e.g., "players/%s")

Security

• tls_cert_file: Path to TLS certificate file for optional FTPS support (optional)
• tls_key_file: Path to TLS private key file for optional FTPS support (optional)

If TLS certificate and key files are provided, the server will support both FTP and FTPS connections. If not provided, the server will operate in FTP-only mode.

Caching and Logging

• character_cache_time: How long to cache character data in seconds (default: 60)
• access_cache_time: How long to cache access.o data in seconds (default: 60)
• access_log_path: Path to access log file (optional)
• app_log_path: Path to application log file (optional)
• log_level: Log level (debug, info, warn, error, panic) (default: info)
• max_log_size: Maximum log file size in bytes before rotation (default: 1000000 / 1MB)
• log_verify_interval: Seconds between file verification checks to detect external moves (default: 45)

When logs exceed max_log_size, they are automatically rotated to timestamped archives in an old/ subdirectory with format <basename>.YYYYMMDD-HHMMSS. The daemon also periodically verifies log files exist and recreates them if externally moved or deleted.

Status Monitoring

• status_dir: Directory for status files (optional). When configured, writes three monitoring files: last_start (startup info), running (live metrics updated every 10s), and last_stop (shutdown reason). The MUD can detect crashes by checking if running is stale (>60s old) without a corresponding last_stop update.

Package Overview

Package	Description
authentication	Handles user authentication by verifying credentials against the MUD's player authentication system. Supports legacy unixcrypt and new Argon2id (PHC format) hashes.
authorization	Implements permission checking by parsing the MUD's access.o object tree. Validates user access rights against the MUD's hierarchical permission system. The access tree is cached to reduce filesystem reads.
ftpserver	Core FTP server implementation built on ftpserverlib. Handles FTP protocol operations while integrating with MUD-specific authentication and authorization.
lpc	Parses LPC (Lars Pensjo C) serialized object format used by LPMuds. Enables direct reading of MUD's data structures like the access control tree.
users	Manages user data by reading and caching the MUD's character files.

License

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