Nmap (Network Mapper) is a free, open-source utility for analyzing network security. It is a popular tool for ethical hacking and is used for network discovery and security auditing. With Nmap, a cybersecurity professional can determine what hosts are available on a network, what services they offer, what operating systems they’re running, the type of firewalls in use, as well as a multitude of other characteristics. It is a tool that an ethical hacker might use during the reconnaissance and scanning phases of the hacking process.
Nmap is available for Windows, Mac OS, and Linux.
Is Nmap Illegal?
Nmap is legal as long as the user owns the resources being mapped, or the owner of those resources has granted the user written permission to scan them
- Aggressive Scan
- Provides far better information than a standard scan, but is more likely to be detected.
- Nmap Scan
- The most basic type of scan is done with the command-line interface (CLI) command Nmap with just a target specified.
- Nmap Scripting Engine
- Allows for the writing of scripts that automate a wide variety of tasks.
- Nmap Version Detection
- Provides information on all identified open ports which interrogating the ports using probes that are understood by specific services.
- No Ping Scan
- Prevents Nmap from doing any host discovery.
- No Port Scan
- Prevents Nmap from doing a port scan after host discovery.
- OS Detection
- Remotely scans a target host and presents details of its operating system if there is a match.
- Ping Sweep
- Identifies active devices on a network by pinging a range of IP addresses.
- TCP Connect Scan
- Establishes a complete connection to the target host.
- TCP SYN Scan
- Performs a scan that can indicate open, filtered, and closed port states with a reduced risk of detection, since it never completes a full TCP connection.
- UDP Scan
- Checks for any UDP ports deployed on a target and can be combined with any TCP scan.