Masscan

Masscan is a command-line TCP port scanner for operators surveying many machines across broad address ranges. It suits users who can define IP targets and ports precisely and who can manage network-level configuration. Its exceptional scan breadth is persuasive, but DNS-name targeting and unadjusted coexistence with the local TCP/IP stack make it a specialist choice.

Overview

Masscan is designed for Internet-scale TCP scanning rather than intensive examination of one host or a small range. Arbitrary port and address ranges, asynchronous transmission and a stated ability to send up to 10 million packets per second from one machine put coverage and throughput at the center of the product. That orientation is valuable for inventory and exposure surveys, but it requires disciplined target definition: users must specify ports, and targets are IP addresses or simple ranges rather than DNS names.

The command-line deployment is free software under the GNU Affero General Public License version 3. The license notice provides no warranty, so organizations should account for their own operational and legal review before incorporating it into a service.

Key features

High-volume, flexible scanning

Masscan accepts arbitrary port and address ranges and sends probes asynchronously. The claimed 10-million-packets-per-second ceiling makes it a strong fit when scanning many machines matters more than detailed, host-by-host investigation. It is less suitable for workflows built around entering hostnames or relying on automatic port selection.

Banner checks and address families

Service detection covers FTP, HTTP, IMAP4, memcached, POP3, SMTP, SSH, SSL, SMBv1, SMBv2, Telnet, RDP and VNC. This gives broad protocol visibility after discovery, although the product's defining advantage remains scan scale rather than deep single-host analysis. IPv4 and IPv6 can be scanned together without switching to a separate IPv6 mode, which simplifies mixed-address inventories.

Output and Nmap familiarity

Results can be written as XML, binary, grepable output, JSON or a list. That range supports both machine processing and straightforward text-based workflows. Usage and output are intended to feel familiar to Nmap users, with some Nmap-compatible options, so experienced Nmap operators have a gentler transition even though Masscan's scanning emphasis is different.

High-speed packet transmission

PF_RING DNA support and the ability to use PF_RING ZC when the adapter name indicates it target high-speed packet transmission. These integrations matter most to operators already using compatible packet-processing infrastructure; they are not a substitute for understanding the network path and host configuration.

Pricing

Masscan — free (Free software under the GNU Affero General Public License v3). There is one free plan, no free trial period and no paid tier. That removes seat or quota charges for teams able to run the command-line software themselves, while the AGPLv3 terms and self-managed deployment place responsibility for compliance, infrastructure and operation on the user. Readers seeking a hosted service, commercial support tier or a packaged allowance should look elsewhere.

Platforms

Masscan runs on Linux, macOS and Windows, and supports self-hosted deployment. Its CLI form suits operators comfortable with local execution and network permissions rather than users looking for a browser-first interface.

Who it's for

Choose Masscan for wide-range surveys across many machines, especially when very high packet rates, mixed IPv4/IPv6 scanning and multiple export formats are priorities. It is a practical fit for security teams and network operators who can supply IP ranges and explicit ports, interpret banner results and isolate its traffic appropriately.

It is a poor fit when targets are primarily DNS names, when the job is an intensive scan of a single machine or small range, or when the scanner must run beside the local TCP/IP stack without special handling. The README warns that Masscan's custom TCP/IP stack can conflict with the local stack; using a separate source IP or firewalling its source port is described as a way to manage that risk.

Pros and cons

Pros

• Exceptional breadth: asynchronous scanning and a stated 10 million packets per second support Internet-scale coverage from one machine.
• Flexible scope: arbitrary address and port ranges let operators tailor large surveys rather than accept fixed scan boundaries.
• Useful service visibility: banner checks span common infrastructure and remote-access protocols.
• Workflow-friendly exports: XML, binary, grepable, JSON and list formats accommodate varied downstream tooling.
• Broad platform reach: Linux, macOS, Windows and self-hosting avoid dependence on a single operating environment.

Cons

• Manual targeting: ports are required and DNS names are not accepted as targets, adding preparation to hostname-driven workflows.
• Network conflict risk: the custom TCP/IP stack may interfere with the local stack unless source addressing or firewalling is arranged.
• Specialist depth: its wide-range design is not the natural choice for intensive, single-host investigation.
• Self-managed responsibility: the free AGPLv3 software carries no warranty in its license notice and provides no hosted plan.

Alternatives

Nmap is the better choice when intensive scanning of one machine or a small range is the priority; it is free, offers a free trial designation and runs on Linux, macOS, Windows and self-hosted environments.

Naabu is another free, open-source port-scanning option with Linux, macOS, Windows, self-hosted and API availability.

NetsCLI suits readers wanting a free MIT-licensed tool with Linux, macOS and Windows support.

RustScan is a free open-source alternative spanning Android, Linux, macOS, Windows and self-hosted use.

ScanSearch is worth considering when a web or API service and metered throughput are preferable; its paid Internet Scanner plan starts at $0.30 a month, billed per kpps/month.

Unicornscan is a free GPL option available through API, Linux, macOS, self-hosted and web deployments.

Angry IP Scanner is a free GPLv2 scanner for Linux, macOS and Windows.

Pentest-Tools Port Scanner fits users seeking a web or API service, with a free tier and a NetSec plan starting at $95 a month.

Browse the wider Port Scanner Software category when none of these deployment models matches your workflow.

Verdict

Masscan is the right pick for experienced operators who need fast, broad TCP coverage across explicitly defined IP ranges and ports, with banner checks and flexible exports at no software cost. Look elsewhere if you need DNS-based targeting, intensive single-host analysis or a managed service that avoids custom-stack network configuration.