Passive Reconnaissance on google.com — What I Found Using Shodan, WHOIS, and DNS Tools

Short summary

Educational walkthrough of passive reconnaissance techniques using publicly available tools (Shodan, WHOIS, DNS enumeration) to map a target's infrastructure without direct system contact. Demonstrates step-by-step methodology on google.com, discovering 37K+ hosts, IP ranges, and subdomains through certificate transparency logs—all legal, non-intrusive security assessment methods.

• •Passive reconnaissance gathers intelligence using only public data sources without triggering alerts or logs
• •Techniques include ASN lookup, Shodan searches, WHOIS queries, DNS enumeration, and SSL certificate inspection
• •Reveals extensive infrastructure details (hosts, IP ranges, software versions, subdomains) on enterprise targets

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