# robertdavidgraham/masscan

TCP port scanner, spews SYN packets asynchronously, scanning entire Internet in under 5 minutes.

Repository: https://github.com/robertdavidgraham/masscan
Canonical: https://ross.abutalabs.com/products/masscan
Language: C
License: AGPL-3.0
License Family: copyleft
Last push: 2026-04-23T20:34:38+00:00

## Health v2 (maintenance only)
Score: 58/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 78, release rhythm 8, longevity 100
- inputs: {"age_days": 4784, "days_push": 132, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 25955, forks 3238 (observed 2026-08-28T04:11:38.766957+00:00)

## What it is
Masscan is an Internet-scale TCP port scanner written in C that transmits 10 million SYN packets per second, capable of scanning the entire Internet in under 5 minutes from a single machine. It uses its own ad hoc TCP/IP stack with asynchronous transmission and offers nmap-like usage and output.

## Use cases
- scan the entire internet for open ports
- fast port scanning of large network ranges
- find hosts with a specific port open across a subnet
- nmap alternative for mass scanning
- audit exposed services on my network
- scan millions of IPs quickly from one machine

## When to choose
- you need to scan huge address ranges or the whole internet at maximum speed
- you want simple SYN port scanning with nmap-like syntax
- you need a dependency-free C tool that runs on Linux, Windows, macOS, and BSD

## When to avoid
- you need in-depth scanning of single machines, service version detection, or NSE scripts - use nmap instead
- you cannot configure firewall rules or source IP/port to avoid conflicts with the local TCP/IP stack
- you need a passive or low-noise scan; masscan's packet rate is highly conspicuous

## Facets
- artifact type: cli-tool
- maturity: active
- function: security, networking, penetration-testing
- domain: security, networking, penetration-testing
- platform: windows, bsd, cli, cross-platform
- tags: port-scanner, tcp-syn-scanning, internet-scale-scanning, nmap-compatible, high-performance, raw-packets, c, command-line, linux, macos

## Member repositories
- robertdavidgraham/masscan (main) score 58

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:38.766957+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T16:55:57.262511+00:00, confidence not recorded.
  - readme: https://github.com/robertdavidgraham/masscan (fetched 2026-08-28T04:11:38.766957+00:00, sha f7e45c6499e5)
- Data as of 2026-08-30T08:39:29.467469+00:00.