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Censys

Tool manual · Kali & common usage

OSINT · Intermediate · OSINT lane

IntermediateOSINT — Internet-wide
Authorized usage only. Capture and inspect traffic only on systems and networks you own or have written permission to analyze.

What is Censys?

Censys indexes internet-facing hosts/certs for attack-surface insight.

Query exposed services belonging to assets you own/are authorized to review.

Official website: Censys · Documentation

When do you use it?

  • You need Search certificates, hosts, and services exposed on the internet.
  • You are following a CYNARKS lab or authorized engagement that calls for Censys.
  • You already tried simpler checks and need this tool’s deeper capability.

Who uses it?

  • OSINT analysts
  • Investigators (lawful use)
  • Red teamers (authorized recon)

How do you use it? (typical flow)

  1. Install Censys using the steps below (prefer Kali package or official installer).
  2. Confirm you have authorization for the target (lab VM, own system, or written scope).
  3. Run --help / man (or the Help section) to see current flags for your version.
  4. Start with a safe example from Basic commands against localhost or an authorized lab target.
  5. Record what you ran, what you observed, and any follow-up (filter, report, remediation).

Help & manual (like man / --help)

Every serious tool has a built-in way to look up flags. Learn these first so you are not stuck memorizing every option.

  1. 1. Site

    https://search.censys.io/

Kali Linux

Web/API — register for API keys; use responsibly.

1. Installation

OSInstallation
Kali LinuxWeb/API — register for API keys; use responsibly.
Webhttps://search.censys.io/

2. Basic commands

  1. 1. Find unexpected services

    Search your org ASN or domain

    Find unexpected services

  2. 2. Show help

    Search --help

    List flags for your installed version (same habit as man/--help).

  3. 3. Short help

    Search -h

    Alternate help flag when supported.

5. Useful features

  • Certificates
  • Host history
  • Queries

6. Practical examples

  1. Example 1: Find unexpected services

    Search your org ASN or domain

    Find unexpected services

  2. Example 2: Show help

    Search --help

    List flags for your installed version (same habit as man/--help).

  3. Example 3: Short help

    Search -h

    Alternate help flag when supported.

7. Important notes

  • Read-only research — remediation is on asset owners.
  • Authorized targets only — labs, systems you own, or written permission.
  • Prefer reading --help / man / official docs for your installed version; flags change over time.

Related course: ethical hacking penetration testing · soc analyst blue team · Commands: /osint