fn0rd.io Scanner

About

The fn0rd.io Scanner is a distributed internet scanning system designed to index and categorize internet-facing services. This is a volunteer effort to help strengthen the global security posture by mapping internet infrastructure, identifying vulnerable systems, and providing actionable intelligence to the security community.

Mission

Our mission is to create a comprehensive, up-to-date index of internet services that can be used by researchers, security professionals, and system administrators to:

• Identify vulnerable systems before malicious actors can exploit them
• Track the adoption of security practices across the internet
• Provide early warning of emerging threats
• Support academic research into internet security trends

How It Works

The scanner operates as a distributed system with a central coordinator that assigns scanning tasks to volunteer nodes:

1. Volunteer scanners connect to a coordinator service
2. The coordinator assigns IP ranges to scan
3. Scanners perform non-intrusive probes using Nmap
4. Results are securely sent back to the coordinator for analysis
5. Findings are aggregated and made available to the security community

Technical Details

Authentication

The scanner uses ED25519 cryptographic keys to authenticate with the coordinator:

• On first run, a new keypair is automatically generated and stored in the state directory
• The public key is transmitted during registration
• All results are cryptographically signed before submission

Scanning Process

The scanner uses Nmap to probe targets with the following characteristics:

• Connect scan (TCP handshake) rather than SYN scanning
• Service version detection
• Basic vulnerability assessment using the "vulners" script
• Banner grabbing for service identification

Installation

Pre-built binaries are available for Linux, *bsd, macOS, and Windows on the releases page

Building from Source

Prerequisites

• Go 1.23 or higher
• Nmap
• Linux/BSD/macOS environment (Windows support limited/untested)

Build Steps

git clone https://github.com/fn0rd-io/scanner.git
cd scanner
go build ./cmd/scanner

Usage

./scanner

Command-Line Options

• --coordinator - URL of the coordinator service (default: "https://coordinator.fn0rd.io")
• --workers - Number of concurrent workers (default: 4× CPU cores)
• --logfile - Log file path (default: STDOUT)
• --statedir - Directory to store state (default: /var/lib/fn0rd)
• --iface - Network interface to use for scanning (optional)

State Directory Structure

The scanner maintains state in the directory specified by --statedir:

• identity - ED25519 private key in PEM format used to authenticate with the coordinator

Ethics and Responsible Scanning

This project is committed to ethical internet scanning:

• We perform only non-intrusive scans (TCP connect rather than SYN scans)
• We respect opt-out requests (contact us to be excluded from scanning)
• We follow responsible disclosure for any vulnerabilities found
• We minimize bandwidth usage and system impact with timing controls

Opting Out

System administrators can opt out of scanning by creating an issue in this repository with the title "Opt-Out Request" and the IP range to exclude.

Contributing

We welcome contributions from the security community! Whether you can run a scanner node, improve the codebase, or help analyze results, there's a place for you in this project.

Development

The scanner is written in Go and uses:

• Connect (gRPC) for coordinator communication
• Nmap for service discovery and vulnerability assessment
• ED25519 cryptography for authentication and signing

To contribute code improvements, please submit a pull request with your changes.