Introduction

In this tutorial, we'll cover how to use theHarvester to collect emails and subdomains from an ethical target (e.g., your own domain). Key OSINT tool for Red Team sims, but always with permission. We use Kali 2025.

Installation and Setup

If you don't have it, install on Kali:

sudo apt update
sudo apt install theharvester

Update sources (optional, for more data):

theHarvester --update

Basic Usage: Collect Emails

Example: Target "example.com" (swap for an ethical one).

theHarvester -d example.com -l 500 -b google,linkedin,bing

Flag explanations:

  • -d: Target domain.
  • -l: Result limit (500 max per source).
  • -b: Sources (google, linkedin, etc.; full list with --help).

Output: Emails like "admin@example.com", hosts like "sub.example.com".

Advanced Usage: Export and Filter

Export to CSV for analysis:

theHarvester -d example.com -l 500 -b all -f output.csv

Filter with grep (e.g., emails only):

cat output.csv | grep '@'

Ethical tip: Use in labs or with consent; integrate into your TFG for phishing sims (e.g., generate payloads with collected emails).

Conclusion

With theHarvester, speed up your OSINT recon. Practice on your own VM. Next tutorial: Integrate with Maltego. Share your output in comments (anonymized)! 🐾⚡