Foot printing is the reconnaissance stage of hacking where an attacker gathers information about the target organization before launching an attack. Foot printing techniques include:
Web searching – Finding organization info through search engines, job listings etc.
DNS interrogation – Performing DNS lookups to gather hostnames, IPs, MX records etc.
Network scanning – Scanning IP ranges to map out active hosts and open ports.
Email tracking – Tracking email sender IPs and headers to learn about mail servers.
Social engineering – Posing as colleagues to trick employees into revealing sensitive network details.
WHOIS lookups – Harvesting registrant info, IPs, domains etc. from public WHOIS records.
Competitive intelligence – Analyzing what competitors reveal about technologies to build attack plans.