Cybersecurity Notes beginner

Module 02 — Footprinting and Reconnaissance

Passive and active information gathering: Netcraft, WHOIS, DNSDumpster, Shodan, Sublist3r, Recon-ng, Sherlock and more.

Updated Aug 3, 2026 2 min read 4 views
#CEH#OSINT#Recon#Footprinting
Back to category

Passive and Active Information Gathering

Introduction

Footprinting and Reconnaissance are the first phases of ethical hacking. The goal is to collect as much publicly available information as possible about a target before performing active enumeration or exploitation.

Note

Passive reconnaissance never touches the target directly. Active reconnaissance does — always stay inside the scope of your written authorisation.

Netcraft

Purpose — Netcraft provides detailed information about websites and domains.

It can identify:

  • Hosting provider
  • Web server
  • Operating system
  • Domain history
  • Technologies used
  • Website ranking
  • Subdomains

Websitenetcraft.com/tools

Site Report

Find infrastructure and technologies used by any website — sitereport.netcraft.com

Threat Map

Current cyber threat intelligence — netcraft.com/resources/threat-map

Search subdomains and DNS records — searchdns.netcraft.com

WHOIS

Purpose — Retrieve domain registration information.

Useful websites

Website uptimewho.is/uptime

DNSDumpster

Purpose — DNSDumpster discovers hosts related to a target domain.

Useful for:

  • Subdomains
  • DNS records
  • Network mapping
  • Infrastructure discovery

Websitednsdumpster.com

Pentest-Tools

Purpose — Provides online reconnaissance and security assessment tools.

Websitepentest-tools.com

Internet Archive

Purpose — View historical versions of websites.

Useful for recovering:

  • Old pages
  • Images
  • JavaScript
  • Documents
  • Source code
  • Deleted content

Websitearchive.org

Tip

Archived JavaScript and source files often expose old API endpoints, internal hostnames and credentials that were removed from the live site.

Shodan

Purpose — Search engine for Internet-connected devices.

Useful for:

  • Servers
  • Cameras
  • Routers
  • IoT devices
  • Open ports
  • Exposed services

Websiteshodan.io

Google Earth & Google Maps

Purpose — Find the physical location of an organization or target.

Websites

Financial Information

Useful websites

Google Alerts

Purpose — Receive notifications whenever new content is published about a target.

Websitegoogle.com/alerts

Social Media Footprinting

Useful platforms

  • LinkedIn
  • Facebook
  • X (Twitter)

Purpose — Gather employee names, email formats, technologies, locations and organizational information.

IP Geolocation

Websiteip2location.com

Purpose — Locate public IP addresses.

Traceroute

Purpose — Display the network path to a destination.

Windows

cmd
tracert facebook.com

Linux

bash
traceroute facebook.com

Sublist3r

Purpose — Enumerate subdomains.

Installation

bash
sudo apt update
sudo apt install sublist3r

Example

bash
sublist3r -d eccouncil.org -o eccouncil_info.txt

View output

bash
cat eccouncil_info.txt

Recon-ng

Purpose — Reconnaissance framework for gathering OSINT.

Example

bash
recon-ng
keys add github_api YOUR_GITHUB_TOKEN
workspaces create mywork
marketplace search
marketplace install recon/domains-hosts/hackertarget
modules load recon/domains-hosts/hackertarget
options set SOURCE eccouncil.org
run
exit

Warning

Never commit or share API keys added to Recon-ng — they are stored in plain text inside the workspace database.

Sherlock

Purpose — Search usernames across hundreds of websites.

Installation

bash
sudo apt install sherlock

Example

bash
sherlock "Elon Musk"

Save output

bash
sherlock "Elon Musk" -o sherlock_result.txt

View output

bash
cat sherlock_result.txt

Additional Resources

ToolPurposeLink
NetScanToolsNetwork recon toolkitnetscantools.com
PingPlotterLatency and route analysispingplotter.com
Email Tracker ProEmail header tracingemailtrackerpro.com