Masscan

Overview

Masscan is a command-line TCP port scanner for operators scanning many machines across broad address ranges. It is best suited to users who can define targets and ports precisely and manage network-level configuration. Its high-volume focus is a strong fit for broad coverage, but DNS-name targeting and unadjusted coexistence with the local TCP/IP stack are poor fits.

Key features

Broad, asynchronous scans

Masscan accepts arbitrary port and address ranges and transmits asynchronously. The project says one machine can transmit 10 million packets per second, a target that makes it compelling when scan breadth matters more than intensive inspection of one host. That pace does not make target selection optional: users must specify ports, and targets must be IP addresses or simple ranges rather than DNS names.

Service checks, IPv6 and exports

Banner checks cover FTP, HTTP, IMAP4, memcached, POP3, SMTP, SSH, SSL, SMBv1, SMBv2, Telnet, RDP and VNC. IPv4 and IPv6 can be scanned together without a separate IPv6 mode. XML, binary, grepable, JSON and list output give teams several ways to route results into their workflows.

Nmap familiarity and packet transmission

Masscan's usage and output are designed to be familiar to Nmap users, with some Nmap-compatible options. PF_RING DNA support and use of PF_RING ZC when the adapter name indicates it address high-speed packet transmission, making these useful considerations for operators with compatible setups rather than general-purpose conveniences.

Operational and security considerations

The README warns that Masscan's custom TCP/IP stack can conflict with the local stack; it describes using a separate source IP or firewalling Masscan's source port as mitigations. That configuration burden matters on machines doing other network work. The project also describes a vulnerability bounty and use of functions such as safe_strcpy() instead of strcpy(). Masscan is free software under the GNU Affero General Public License version 3, whose license notice states that it comes with no warranty.

Pricing

Masscan is free software under the GNU Affero General Public License version 3. Its Masscan plan costs nothing. With no paid tier or trial, the trade-off is straightforward: there is no purchase decision, but users take on the setup and operational demands of running the command-line tool themselves.

Platforms

Masscan supports Linux, macOS and Windows, and is self-hosted. Its command-line deployment suits operators comfortable running scans in their own environment.

Who it's for

Choose Masscan when the job is scanning many machines across wide ranges and high throughput is central. It is less suitable when targets are supplied as DNS names, when a scan needs detailed attention on one machine or a small range, or when an operator cannot accommodate the custom-stack conflict risk.

Pros and cons

• Pro: Arbitrary port and address ranges, asynchronous transmission and a stated 10-million-packet-per-second capacity suit broad scanning workloads.
• Pro: IPv4 and IPv6 can be scanned together, and five output formats support varied result-handling workflows.
• Pro: Banner checks cover a broad set of common services, including SSH, HTTP, SMB, RDP and VNC.
• Con: Users must specify ports and provide IP addresses or simple ranges; DNS names are not accepted as targets.
• Con: The custom TCP/IP stack may conflict with the local stack, requiring network configuration such as a separate source IP or source-port firewalling.
• Con: Its wide-range focus is not the stated design priority for intensive scanning of a single machine or small range.

Alternatives

For other options, browse Port Scanner Software. Pick Naabu if you want a free, MIT-licensed port-scanning tool with API support as well as Linux, macOS, self-hosted and Windows platforms. NetsCLI is another free option for Linux, macOS and Windows; its MIT-licensed library and MCP server are published on crates.io for Rust projects.

Choose RustScan if Android support matters; it is a free open-source port scanner also available for Linux, macOS, self-hosted and Windows. Angry IP Scanner is a free GPLv2 option for Linux, macOS and Windows.

Nmap is the more fitting choice for intensive scanning of one machine or a small range; its free end-user license costs nothing and does not allow redistribution within commercial software or hardware products. Choose ScanSearch if a paid Internet-scanning plan with a stated kpps range and CSV/JSON export is a better match: its Internet Scanner plan is $0.30 a month, billed per kpps/month, for 100–10,000 kpps, unlimited results per scan and a queue of up to 10 scans.

Unicornscan is another free option, with downloadable packages and source under the GPL. Pentest-Tools Port Scanner offers a free web/API tier for open-port and service discovery, plus a NetSec plan starting from $95 a month.

Verdict

Masscan is a strong choice for operators who need fast, broad TCP port scans and can supply explicit IP ranges, ports and careful network configuration. Its high-volume orientation and flexible exports are the reasons to choose it; look elsewhere if you need DNS targets, intensive single-host scanning, or a workflow that cannot tolerate adjustments around its custom TCP/IP stack.