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Masscan

github.com

Free plan Open source WindowsmacOSLinuxSelf-hosted
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Spec score 8.7 #2 of 26 in Port Scanner Software

What it is

Masscan is a free command-line TCP port scanner for scanning many machines across wide address ranges. The project says one machine can transmit 10 million packets per second. It supports asynchronous transmission, arbitrary port and address ranges, and scanning IPv4 and IPv6 together without a separate IPv6 mode. Banner checks cover protocols and services including FTP, HTTP, IMAP4, memcached, POP3, SMTP, SSH, SSL, SMBv1, SMBv2, Telnet, RDP and VNC. Results can be saved as XML, binary, grepable, JSON or list output. Its usage and output are intended to be familiar to Nmap users, with some Nmap-compatible options. Masscan runs on Linux, macOS and Windows and is available for self-hosting. The project describes PF_RING DNA support for high-speed transmission and says it can use PF_RING ZC when the adapter name indicates it. It is free software under the GNU Affero General Public License version 3, whose notice states there is no warranty. Users must specify ports and target IP addresses or simple ranges; DNS names are not accepted. The README warns that its custom TCP/IP stack can conflict with the local stack and describes using a separate source IP or firewalling its source port.

Spec sheet

What it does
Masscan is an Internet-scale TCP port scanner intended to discover open ports across very large address spaces.Read 15 Oct 2026 · github.com
Purpose
Masscan is an Internet-scale TCP port scanner designed for wide-range scanning of many machines.Read 5 Oct 2026 · github.com
Intended users
The README describes Masscan as tuned for scanning many machines across wide ranges, while Nmap is described as designed for intensive scanning of a single machine or small range.Read 5 Oct 2026 · github.com
Platforms
Linux is the primary target; the code also runs on Windows and macOS, and the README gives build instructions for FreeBSD.Read 5 Oct 2026 · github.com
Integrations
The project describes PF_RING DNA support for high-speed packet transmission and says Masscan can use PF_RING ZC when the adapter name indicates it.Read 5 Oct 2026 · github.com
Security
The project says it offers a vulnerability bounty and uses functions such as safe_strcpy() in place of strcpy().Read 5 Oct 2026 · github.com
License
Masscan is free software under the GNU Affero General Public License version 3, with no warranty stated in the license notice.Read 5 Oct 2026 · github.com
Maker
The repository credits Robert David Graham as the creator and gives his contact email and @ErrataRob account.Read 15 Oct 2026 · github.com
Address and port ranges
Masscan accepts arbitrary IP address ranges and port ranges, including IPv4 and IPv6 examples.Read 15 Oct 2026 · github.com
Asynchronous scanning
It sends SYN packets asynchronously and uses a design comparable to scanrand, Unicornscan and ZMap.Read 15 Oct 2026 · github.com
Banner checks
Banner checking is supported for FTP, HTTP, IMAP4, memcached, POP3, SMTP, SSH, SSL, SMBv1, SMBv2, Telnet, RDP, and VNC.Read 5 Oct 2026 · github.com
Banner protocols
Banner checking is documented for FTP, HTTP, IMAP4, memcached, POP3, SMTP, SSH, SSL, SMBv1, SMBv2, Telnet, RDP and VNC.Read 15 Oct 2026 · github.com
Banner-grab hazard
The host stack can send reset packets after SYN-ACK responses, terminating connections before Masscan captures banners.Read 15 Oct 2026 · github.com
Build requirements
The basic Linux build requires Git, Make and a C compiler such as GCC or Clang, with no other major dependencies described.Read 15 Oct 2026 · github.com
Compatibility
Masscan's usage and output are designed to be familiar to Nmap users, with some Nmap-compatible options.Read 5 Oct 2026 · github.com
Configuration export
The --echo option prints the current configuration so it can be saved and reused as an input configuration file.Read 15 Oct 2026 · github.com
Copyright date
The licence notice identifies copyright as 2013 Robert David Graham.Read 15 Oct 2026 · github.com
Custom TCP/IP stack
Masscan includes its own ad hoc TCP/IP stack, which can conflict with the host operating system stack.Read 15 Oct 2026 · github.com
Distributed scans
The Debian manual documents --shard for dividing a scan across machines and resume indexes for assigning chunks to workers such as Amazon EC2 instances.Read 15 Oct 2026 · manpages.debian.org
High-speed integration
PF_RING ZC can be used beyond about two million packets per second with a compatible Intel 10-gigabit adapter and drivers.Read 15 Oct 2026 · github.com
IPv6
IPv4 and IPv6 can be scanned together, without a separate IPv6 mode.Read 5 Oct 2026 · github.com
Kali package
Kali lists Masscan as a TCP port scanner installable with sudo apt install masscan, with an installed size of about 516 KB and libc6 and libpcap dependencies.Read 15 Oct 2026 · kali.org
Licence
Masscan is released under the GNU Affero General Public License version 3.Read 15 Oct 2026 · github.com
Limit: command-line interface
The same review lists the lack of a graphical interface and the need for command-line operation as disadvantages.Read 15 Oct 2026 · scanitex.com
Limit: documentation depth
A university evaluation found Masscan's documentation mainly consisted of its README and C source, with less documentation than ZMap.Read 15 Oct 2026 · net.in.tum.de
Limit: host inspection
The same evaluation records that Masscan does not provide operating-system detection and offers a smaller capability set than Nmap.Read 15 Oct 2026 · net.in.tum.de
Limit: network overload
A Masscan usage review warns that setting the transmission rate too high can overload networks or cause IP blocking.Read 15 Oct 2026 · scanitex.com
Limit: shallow vulnerability coverage
A 2025 IoT-security paper describes Masscan and similar scanners as broad discovery tools that do not detect deeper firmware or device-specific vulnerabilities.Read 15 Oct 2026 · preprints.org
Limit: virtual networking
A BSides security-crawler presentation reports that Masscan performed poorly with some virtual network configurations, leading the team to build a custom asynchronous TCP scanner.Read 15 Oct 2026 · markevich.org
Limit: Windows throughput
A Microsoft Q&A report measured about 25,000 packets per second on Windows compared with about 500,000 on Linux in that user's test.Read 15 Oct 2026 · learn.microsoft.com
Notable limitation
Masscan requires users to specify ports and accepts IP addresses or simple ranges rather than DNS names as targets.Read 5 Oct 2026 · github.com
Operational consideration
The README warns that Masscan's custom TCP/IP stack can conflict with the local stack and describes using a separate source IP or firewalling its source port.Read 5 Oct 2026 · github.com
Output
Supported output formats are XML, binary, grepable, JSON, and list.Read 5 Oct 2026 · github.com
Praise: port-range speed
A comparative thesis concluded that Masscan was faster than ZMap when scanning port ranges because ZMap initializes separately for each port.Read 15 Oct 2026 · mnm-team.org
Praise: scanning efficiency
SaaSHub summarizes public discussion as repeatedly praising Masscan's speed and efficiency on large-scale network scans.Read 15 Oct 2026 · saashub.com
Result export
Debian's manual documents XML output, binary scan files, reading saved scans and importing XML into databases or similar systems.Read 15 Oct 2026 · manpages.debian.org
Scan speed
The project says one machine can scan the entire Internet in under five minutes at up to 10 million packets per second.Read 15 Oct 2026 · github.com
Scanning
It supports arbitrary port and address ranges and asynchronous transmission.Read 5 Oct 2026 · github.com
Scope limitation
The maker positions it for broad scans of many machines rather than intensive analysis of individual hosts.Read 15 Oct 2026 · github.com
Speed
The project says Masscan can transmit 10 million packets per second from a single machine.Read 5 Oct 2026 · github.com
Stack workaround
The documentation recommends a separate source IP or configured source ports protected by firewall rules when avoiding stack conflicts.Read 15 Oct 2026 · github.com
Supported operating systems
The maker identifies Linux as the primary target and provides build guidance for Windows, macOS and FreeBSD.Read 15 Oct 2026 · github.com
Testing
The repository includes make test and a --selftest command, with the documented expected result of selftest success.Read 15 Oct 2026 · github.com
Windows build limitation
The maker states that the Cygwin build does not work, while Visual Studio and MinGW builds are supported.Read 15 Oct 2026 · github.com

Plans and prices

Free Free Internet-scale scanning · arbitrary IP and port ranges · command-line use Read 15 Oct 2026 · github.com
Masscan Free Free software under the GNU Affero General Public License v3 Read 5 Oct 2026 · github.com

Every Masscan plan and price →

Strong points and limits

Strong points

  • Free under the GNU Affero General Public License v3.
  • Scans IPv4 and IPv6 together.
  • Supports several banner checks.
  • Offers five output formats.
  • Supports asynchronous transmission.

Limits

  • Targets must be IP addresses or simple ranges.
  • Users must specify ports.
  • Its custom TCP/IP stack can conflict with the local stack.
  • The license notice states there is no warranty.

Who it suits

Masscan suits users scanning many machines across wide ranges who can work with IP addresses or simple ranges and specify ports. Its command-line interface and Nmap-compatible options may suit users familiar with Nmap.

Verdict

Masscan is aimed at wide-range scanning, with asynchronous transmission and multiple output formats. Its target requirements and potential TCP/IP stack conflict are important operational constraints.

Where Specifiction places it

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