Learn
LoginRegister
← All tools

theHarvester

Tool manual · Kali & common usage

OSINT · Beginner · OSINT lane

BeginnerOSINT
Authorized usage only. Capture and inspect traffic only on systems and networks you own or have written permission to analyze.

What is theHarvester?

theHarvester gathers emails, names, and hosts from public sources for OSINT.

Early passive recon on domains you are allowed to investigate.

Official website: theHarvester · Documentation

When do you use it?

  • You need Collect emails, names and subdomains from public sources.
  • You are following a CYNARKS lab or authorized engagement that calls for theHarvester.
  • You already tried simpler checks and need this tool’s deeper capability.

Who uses it?

  • OSINT analysts
  • Investigators (lawful use)
  • Red teamers (authorized recon)

How do you use it? (typical flow)

  1. Install theHarvester using the steps below (prefer Kali package or official installer).
  2. Confirm you have authorization for the target (lab VM, own system, or written scope).
  3. Run --help / man (or the Help section) to see current flags for your version.
  4. Start with a safe example from Basic commands against localhost or an authorized lab target.
  5. Record what you ran, what you observed, and any follow-up (filter, report, remediation).

Help & manual (like man / --help)

Every serious tool has a built-in way to look up flags. Learn these first so you are not stuck memorizing every option.

  1. 1. Help

    theHarvester -h

    Data source flags (-b).

Kali Linux

Preinstalled on many Kali builds: theHarvester.

1. Installation

OSInstallation
Kali LinuxPreinstalled on many Kali builds: theHarvester.
Linuxsudo apt install theharvester

2. Basic commands

  1. 1. Search public sources for a domain

    theHarvester -d example.com -b duckduckgo

    Search public sources for a domain

  2. 2. Show help

    theHarvester --help

    List flags for your installed version (same habit as man/--help).

  3. 3. Short help

    theHarvester -h

    Alternate help flag when supported.

  4. 4. Show all options and usage

    --help

    Show all options and usage

Options / flags

OptionPurpose
--helpShow all options and usage

5. Useful features

  • Data sources
  • Result interpretation

6. Practical examples

  1. Example 1: Search public sources for a domain

    theHarvester -d example.com -b duckduckgo

    Search public sources for a domain

  2. Example 2: Show help

    theHarvester --help

    List flags for your installed version (same habit as man/--help).

  3. Example 3: Short help

    theHarvester -h

    Alternate help flag when supported.

  4. Example 4: Show all options and usage

    --help

    Show all options and usage

7. Important notes

  • theHarvester is used legitimately by security teams for authorized testing, defense validation and education.
  • Authorized targets only — labs, systems you own, or written permission.
  • Prefer reading --help / man / official docs for your installed version; flags change over time.

Related course: ethical hacking penetration testing · soc analyst blue team · Commands: /osint