Tag: Footprinting

Footprinting: How Hackers Build a Profile of Your Organisation

May 14, 2026

Footprinting is the first step in any targeted intrusion — building a comprehensive profile of a target organisation including domain names, IP addresses, open ports, services, OS details, user accounts, routing tables, and SNMP information.

Footprinting Techniques

TechniquePurpose
Ping SweepIdentify which IP addresses in a range are alive
TCP ScanDetermine open services on target hosts
UDP ScanProbe UDP ports; ICMP “unreachable” replies indicate no service
OS IdentificationSend malformed packets; unique responses fingerprint the OS
HTTP FingerprintingIdentify web server type from headers and error responses

HTTP Fingerprinting Example

nc 200.44.76.254 80
HEAD / HTTP/1.0
HTTP/1.1 200 OK
Server: Apache/1.3.3 (Unix) (Red Hat/Linux)

The Server header directly reveals the web server software and OS. Best practice: suppress or customise this banner.

Prevention Guidance

  • Shut down unnecessary services and ports; perform post-installation hardening.
  • Suppress or customise HTTP server banners.
  • Keep all patches current — daily or weekly if possible.
  • Use an IDS configured to detect footprinting patterns.
  • Change all default passwords after every installation.
  • Lock consoles physically — an unlocked desktop gives instant network access.