dnsgen

A fast, lightweight, and modern Go port of dnsgen by AlephNullSK.

dnsgen generates domain name permutations from a list of input domains and an optional wordlist. It is designed to assist in security assessments, bug bounty hunting, and subdomain discovery.

🚀 Key Features

• Original Logic Parity: Implements all 8 core permutation generators from the Python version.
• Fast and Lightweight: Built in Go for high execution speed and low resource consumption.
• Zero External Data Dependencies: The default wordlist is embedded directly into the binary using Go's //go:embed.
• Bug Fixes: Resolves an issue in the original Python version where custom words extracted from input domains with length constraints (-l / --wordlen) were ignored during generation.
• Pipeline-Friendly: Correctly writes logs to stderr and clean domain outputs to stdout, facilitating easy integration with commands like massdns or nmap.

📦 Installation

To install dnsgen, ensure you have Go installed, then run:

GOPROXY=direct go install github.com/ranjbarhadi/dnsgen@latest

(Or build it locally from the repository root):

go build -o dnsgen main.go

🛠 Usage

You can feed domains to dnsgen via standard input (stdin) or by passing a file path.

# Using stdin
cat domains.txt | ./dnsgen -

# Using input file
./dnsgen domains.txt

CLI Options

Usage:
  dnsgen [flags] [INPUT_FILE]

Flags:
  -f, --fast             Fast generation mode (skips insertion permutators to generate a smaller subset)
  -h, --help             help for dnsgen
  -l, --wordlen int      Minimum length of custom words extracted from domains (default 6)
  -o, --output string    Output file path (defaults to stdout)
  -v, --verbose          Enable verbose logging (outputs stats to stderr)
  -w, --wordlist string  Path to custom wordlist file (uses embedded words.txt by default)

🧠 Permutation Engines Included

dnsgen implements all default generators:

1. Insert Word Every Index: Inserts words from the wordlist at every position between subdomain parts.
2. Modify Numbers: Increments and decrements numbers found in subdomains (preserving leading zero formats, e.g., 01 -> 02).
3. Environment Prefix: Adds common environment-related subdomains (dev, staging, uat, prod, test).
4. Cloud Provider Additions: Prepends cloud platform combinations (e.g. service-cloud).
5. Region Prefixes: Prepends regional formats (e.g. us-east, eu-west).
6. Microservice Patterns: Appends standard microservice identifiers (-service, -api).
7. Internal Tooling: Prepends or appends internal platform indicators (e.g. jenkins, gitlab).
8. Common Ports: Prepends port names or numbers (e.g. 8080, port-8080).

🤝 Acknowledgments

This tool is a Go port of the excellent Python library dnsgen written by AlephNullSK. All core permutation logic and default wordlists originate from their work.