masscan

masscan is an Internet-scale port scanner for sweeping large IPv4 or IPv6 ranges at high packet rates. It is built for broad exposure discovery and lightweight banner collection, not the deeper host-by-host analysis you would normally do with nmap.

• Sweep large CIDR ranges or explicit target lists for open TCP, UDP, or other supported ports, with rate limits, excludes, and resumable config files.
• Collect lightweight service banners from common protocols such as HTTP, SSH, TLS, SMB, RDP, and VNC after open ports are found.
• Split wide scans across shards or adapters and export results as JSON, NDJSON, XML, grepable, binary, or simple list output for later analysis.

• The CLI is non-interactive and explicit, so it fits scripted discovery jobs where an agent needs to inspect exposed network surface area quickly.
• Structured output is real: the source ships JSON and NDJSON writers, which makes downstream parsing and ingestion straightforward.
• It is strongest as an inspect and verify primitive; safe use usually depends on a skill that encodes scope, exclude lists, rate caps, and follow-up handling.

• Banner grabbing uses masscan's separate TCP/IP stack, so source IP or port selection and host firewall rules matter if you want reliable results.
• The tool can send traffic fast enough to disrupt networks or trigger abuse responses, so unattended runs need strict target authorization and conservative rate control.