Nmap
Nmap (Network Mapper) is a free and open-source network discovery and security auditing tool that has become the industry standard for port scanning, service detection, OS fingerprinting, and network inventory. Network administrators, security professionals, and system administrators worldwide rely on Nmap to discover hosts, identify running services, detect open ports, and assess network security posture. Its powerful scripting engine (NSE) extends Nmap with hundreds of built-in scripts for vulnerability detection and service enumeration.
Key Features
- Advanced port scanning — TCP SYN stealth scan, TCP connect scan, UDP scan, TCP ACK scan, SCTP scan, and dozens of other scan techniques for different network environments
- Service version detection — Identify exact service versions (e.g. Apache 2.4.57, OpenSSH 9.3p1, vsftpd 3.0.5) running on detected ports
- OS fingerprinting — Identify operating systems and kernel versions based on TCP/IP stack fingerprinting with high accuracy
- Nmap Scripting Engine (NSE) — Over 600 built-in scripts for vulnerability detection, brute-force auditing, service enumeration, and exploitation verification
- Network discovery — Ping sweeps, ARP scans, and host discovery across IP ranges, CIDR subnets, and domain name resolutions
- Zenmap graphical interface — Official GUI providing interactive topology visualisation, scan comparison, and profile management
- Ndiff — Compare scan results between runs to track changes in network services and hosts over time
- Flexible output formats — Plain text, XML, grepable, and interactive mode for integration with other tools and automation pipelines
- Packet-level control — Customisable timing templates, packet fragmentation, decoy scanning, and raw packet manipulation for advanced use cases
Why Use Nmap?
Whether you are securing a home network or auditing an enterprise infrastructure, Nmap provides the clearest picture of what is actually running on your network — uncovering forgotten services, unauthorised devices, misconfigured firewalls, and exposed ports that no other tool catches. It is the first tool a penetration tester reaches for and the first tool a defender should have in their arsenal.
Use Cases
- Security auditing — Identify exposed services and open ports on your network perimeter that should not be publicly accessible
- Network inventory — Discover all devices on a network segment, including IoT devices, rogue access points, and unauthorised hardware
- Vulnerability assessment — Use NSE scripts to detect known vulnerabilities in running services, such as Heartbleed, Log4j, and weak SSL/TLS configurations
- Firewall testing — Verify that firewall rules are working as intended by scanning from outside and inside the network
- Incident response — Perform rapid reconnaissance of potentially compromised network segments to identify scope and lateral movement
Platform
Linux · macOS · Windows · BSD
Licence
NPSL (Nmap Public Source License)