Subdomain Enumerator

Discover subdomains for any domain using two complementary techniques: DNS brute-force resolution and certificate transparency log mining via crt.sh.

Quick Start

python3 scripts/subenum.py example.com

Commands

# Basic enumeration (built-in wordlist + crt.sh)
python3 scripts/subenum.py example.com

# Custom wordlist
python3 scripts/subenum.py example.com --wordlist /path/to/wordlist.txt

# Faster with more threads
python3 scripts/subenum.py example.com --threads 20

# DNS only (skip crt.sh)
python3 scripts/subenum.py example.com --no-crtsh

# JSON output
python3 scripts/subenum.py example.com --json

# Save results to file
python3 scripts/subenum.py example.com --output subdomains.txt

# Verbose progress
python3 scripts/subenum.py example.com -v

Options

| Flag | Default | Description | |------|---------|-------------| | --wordlist, -w | built-in (~120 words) | Custom wordlist file | | --threads, -t | 10 | Concurrent DNS resolution threads | | --timeout | 15 | HTTP timeout for crt.sh query | | --no-crtsh | off | Skip certificate transparency lookup | | --json | off | Output as JSON | | --output, -o | — | Write results to file | | --verbose, -v | off | Show progress during scan |

Techniques

DNS Brute-force — Resolves {word}.{domain} against DNS for each word in the wordlist. Returns IP addresses for live subdomains.
Certificate Transparency (crt.sh) — Queries public CT logs for certificates issued to *.domain, revealing subdomains that may not respond to DNS but have had TLS certificates.

Dependencies

pip install requests

Notes

Built-in wordlist covers common subdomains (www, api, mail, staging, etc.)
For comprehensive scans, use a larger wordlist (e.g., SecLists DNS wordlists)
Results are deduplicated across sources
Use responsibly — only scan domains you own or have authorization to test