Network scanner — discover hosts and probe open ports on a network.
medium risk
nmap probes hosts and ports to map network topology. Always obtain explicit written permission before scanning any network you don't own or operate.
| Flag | Meaning |
|---|---|
-sV | Detect service versions on open ports |
-O | Enable OS detection |
-p | Ports to scan (-p 22,80,443 or -p 1-1024) |
-sn | Ping scan only — discover live hosts |
--open | Show only open ports |
nmap -sn 10.0.0.0/24Discover live hosts in a /24 subnet · explain & risk-check →nmap -sV -p 22,80,443 10.0.1.5Check specific ports and detect service versions · explain & risk-check →Use `-T4` for faster scanning on local networks. Use `-T2` on slow WAN to avoid triggering rate limits.
Reference text is hand-written and may be incomplete — check man nmap for your version. Test destructive commands on a non-production system first.