Tool · Security

Nmap

Reconnaissance in a penetration test usually starts with Nmap, the free scanner that finds which hosts are alive, which ports are open and which services and versions answer on them. Its scripting engine extends it into vulnerability checks, and administrators audit their own networks with it too. Scanning networks without written permission can be illegal, whatever a tutorial suggests.

Maker's site: nmap.org (opens in a new tab) (no commission).