Recon 101: Tools, Targets, and Tips
#technique #cybersecurity #pentesting
Before a hacker breaks into a system, they learn everything they can about it.
That phase—reconnaissance, or "recon"—is the most critical part of any penetration test, red team operation, or real-world cyberattack.
Think of it like casing a building before a heist.
Whether you're defending your business or learning to ethically hack, understanding recon is non-negotiable.
In this post, we'll cover what recon is, what attackers look for, the best free tools to use, and practical tips to get started.
🧠 What Is Reconnaissance?
Reconnaissance is the process of gathering information about a target—passively or actively—before launching an attack.
In cybersecurity, recon is used to:
- Identify systems, domains, and IPs
- Discover open ports and services
- Find usernames, email addresses, and leaked credentials
- Map out infrastructure (cloud, on-prem, hybrid)
- Spot misconfigurations, shadow IT, or outdated systems
Recon is often Phase 1 of a penetration test, but it's also a daily tool for bug hunters, threat actors, and red teamers.
🎯 What Are the Targets?
Recon can uncover data about multiple layers of your business or network:
| Recon Area | Examples |
|---|---|
| Domains & Subdomains | yourcompany.com, api.yourcompany.com |
| IP addresses & Servers | Web servers, mail servers, exposed databases |
| DNS records | MX, TXT, SPF, DMARC info |
| Employee data | Names, job titles, email formats |
| Tech stack | Frameworks, CMS, versions, cloud providers |
| Leaked info | Password dumps, GitHub secrets, dark web chatter |
🧰 Free Recon Tools to Know
🌐 Passive Recon Tools
No direct interaction with the target. Quiet, stealthy, and useful for OSINT (open-source intelligence).
| Tool | Use |
|---|---|
| Amass | Subdomain enumeration |
| theHarvester | Email, domain, and public record gathering |
| Shodan | Search exposed devices by IP |
| Censys | Scan data for exposed services/certs |
| crt.sh | Find SSL certs linked to domains |
| Hunter.io | Find company email patterns |
| Google Dorks | Advanced search queries to expose info |
🔧 Active Recon Tools
These interact with the target—great for mapping, but more detectable.
| Tool | Use |
|---|---|
| Nmap | Port scanning, service detection, OS fingerprinting |
| Gobuster / Dirb | Brute-force web directories and files |
| WhatWeb / Wappalyzer | Detect web technologies |
| Dig / Nslookup | Query DNS records |
| Traceroute / MTR | Map network paths and latency |
🛠️ Bonus: Build a Recon Workflow
Here's a simple recon flow to start with:
1. Identify target domain(s)
2. Enumerate subdomains (Amass, crt.sh, assetfinder)
3. Discover IP addresses (DNS, dig, Nslookup)
4. Scan for open ports and services (Nmap)
5. Enumerate services (e.g., web ports, FTP, SSH)
6. Identify software, versions, headers (Wappalyzer, WhatWeb)
7. Search for exposed data leaks (theHarvester, GitHub, dark web)
8. Document everything for the next stage
⚠️ Always have permission. Don't scan systems you don't own or have written authorization to test.
🧩 Real-World Recon Story: One Subdomain Away
A small SaaS company launched a new app in beta on beta.company.com.
They didn't secure it. It was indexed by search engines.
An attacker found it using Amass + crt.sh, discovered hardcoded credentials in the JavaScript, and pivoted into the main environment.
One forgotten subdomain = full compromise.
This is why continuous recon is a defense, not just an attack technique.
🤓 Recon Trivia
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"OSINT" (Open-Source Intelligence) originated in military operations long before cybersecurity.
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Shodan was once called "Google for Hackers" because it exposes industrial control systems, webcams, and even smart fridges.
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Subdomain enumeration alone has earned bug bounty hunters millions in payouts from programs like HackerOne.
🔐 Recon Tips for SMB Defenders
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Google your company regularly ("site:yourcompany.com password")
-
Monitor for new subdomains using tools like SecurityTrails or Spyse
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Use services like HaveIBeenPwned to monitor leaked emails
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Audit DNS records for misconfigurations (missing SPF/DKIM/DMARC)
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Run internal Nmap scans regularly to spot forgotten services
✅ Final Thoughts
Recon isn't just the first step in ethical hacking—it's the foundation of security awareness.
Whether you're an IT admin, cybersecurity professional, or curious SMB leader, learning recon means:
- Seeing your business like an attacker would
- Discovering your blind spots
- Getting proactive before someone else does
Want to know what attackers already know about you? Start with recon.
Need help performing a recon sweep on your organization or training your staff in real-world recon techniques?
I offer custom reconnaissance assessments and training sessions built for small to mid-sized businesses.
📧 m1k3@msquarellc.net – Let's uncover what's hiding in plain sight.
Questions about reconnaissance or penetration testing? Reach out directly:
- Email: m1k3@msquarellc.net
- Phone: (559) 670-3159
- Schedule: Book a free consultation
M Square LLC
Cybersecurity | Penetration Testing | No-Nonsense Advice