Masscan
Extremely fast port scanner that can scan the entire internet in minutes by sending packets in parallel.
External Tool
This open-source tool is maintained externally. View the source on GitHub to learn more or run it yourself.
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What is Masscan?
Masscan is an open-source, Internet-scale port scanning tool designed to rapidly scan large networks by transmitting asynchronous SYN packets at high speeds. It can scan the entire IPv4 address space in under 5 minutes, achieving rates of up to 10 million packets per second from a single machine. This tool is primarily used by cybersecurity professionals, network administrators, and researchers to identify open ports and potential vulnerabilities across vast IP ranges. Its asynchronous architecture allows it to handle massive-scale scans efficiently, addressing the limitations of traditional port scanners like nmap, which are optimized for smaller, targeted scans. Masscan’s ability to process data in parallel makes it ideal for tasks such as network discovery, security audits, and real-time threat detection. Its AGPL-3.0 license and GitHub popularity (25,000 stars) reflect its value in both academic and professional contexts.
How it works
Masscan is a high-speed, asynchronous TCP port scanner that leverages raw socket programming to send SYN packets to target IP addresses. It prioritizes scalability, enabling users to scan millions of hosts simultaneously. Its primary purpose is to quickly identify open ports and services across large networks, making it a critical tool for security assessments and network monitoring. Unlike traditional scanners that scan one host at a time, Masscan uses parallel processing to scan thousands of hosts concurrently. This approach drastically reduces scan duration, though it sacrifices some depth compared to tools like nmap. Its design targets efficiency rather than granular vulnerability analysis, making it suitable for broad reconnaissance tasks. Masscan’s core capabilities include scanning the entire IPv4 address space in under 5 minutes, transmitting 10 million packets per second, and supporting custom IP ranges and port lists. It can detect open ports, operating systems, and services, with output similar to nmap. Its asynchronous architecture allows it to bypass rate-limiting mechanisms common in traditional network defenses.
How to use it
- 1Install Masscan via its GitHub repository or package managers. 2. Use the command-line interface to specify target IP ranges, ports, and scan options. 3. Run the scan with parameters like `--ip-file` for custom IP lists or `--ports` to define specific ports. 4. Analyze the output for open ports and potential vulnerabilities. Practical tips include using rate limiting (`--rate`) to avoid overwhelming networks, specifying output formats (e.g., `--output-format=json`), and combining it with tools like Nmap for deeper analysis. Always ensure compliance with legal and ethical guidelines when performing scans.
What it can do
- fast port scanner
Use cases
Assumptions and limitations
Assumptions
- source: https://github.com/robertdavidgraham/masscan
- license: AGPL-3.0 — free to use
- privacy: Self-hosted — you control your data
Limitations
- Legal and ethical restrictions may limit its use in live environments
- May trigger network defenses due to high packet rates
- Lacks detailed service version detection compared to nmap
- Requires advanced technical knowledge for optimal configuration
- Does not support IPv6 natively (though workarounds exist)
Understanding the result
Extremely fast port scanner that can scan the entire internet in minutes by sending packets in parallel.
Tool details
- Clearly flagged when a network request is needed.
- No account, no sign-up, and no tracking of your content.
- Powered by (MIT).
- Built with
- (robertdavidgraham/masscan)
- License
- MIT
- Runs locally
- No — requires a network request
- Verification
- Not yet verified
- Input
- Query
- Output
- Text
Built with robertdavidgraham/masscan. OpenToolVault provides the discovery and browser interface while crediting the original project maintainers.
- Built with
- License
- MIT
Open-source project
OpenToolVault is an independent directory. We are not affiliated with or endorsed by this project.
References
- / — GitHub Repository
Upstream project · GitHub
- AGPL-3.0 License
Upstream project
Frequently asked
What is the primary advantage of Masscan over traditional port scanners?
Masscan’s asynchronous architecture enables it to scan millions of hosts simultaneously, reducing scan time from hours to minutes. Unlike sequential scanners like nmap, it transmits packets in parallel, making it ideal for large-scale network discovery. However, it sacrifices some depth in service detection compared to tools focused on individual hosts.
How does Masscan handle network congestion or firewall restrictions?
Masscan uses fragmented packets and mimics legitimate traffic patterns to bypass basic firewall rules. It also allows rate limiting via the `--rate` parameter to avoid overwhelming networks. However, advanced firewalls or intrusion detection systems may still block its traffic, requiring additional evasion techniques.
How can I scan a custom IP range with Masscan?
Use the `--ip-file` option to specify a text file containing IP addresses or ranges. For example: `masscan --ip-file=targets.txt --ports=22,80,443`. Alternatively, use CIDR notation directly in the command line, like `masscan -p 22,80,443 192.168.1.0/24`.
How does Masscan compare to nmap?
Masscan excels in speed and scalability, scanning entire networks in minutes, while nmap prioritizes detailed service and OS detection. Masscan’s asynchronous model is ideal for reconnaissance, whereas nmap’s sequential approach is better for in-depth analysis. Both tools complement each other in security workflows.
What should I do if Masscan is blocked by a firewall?
Try adjusting the scan rate with `--rate` to avoid triggering rate-based filters. Use fragmented packets with `--fragmented` to bypass simple inspection rules. If possible, scan during off-peak hours or coordinate with network administrators to ensure compliance with policies.