Description
The first question when you inherit an unfamiliar network is which devices are online, which ports they have open and what is running on them. Pinging and telnetting machines one by one is slow and misses things. Nmap does exactly this: point it at an IP range and it sends probes, then hands back a list of live hosts, open ports and service versions.
It is a command line tool, so it fits naturally into scripts you run on a schedule, and comparing two runs shows when someone quietly started a new service. Targets range from a single machine to hundreds of devices, and the response fingerprint lets it guess the remote operating system. If you prefer a GUI, the bundled Zenmap lets you pick scan profiles, save results and browse them by host and service.
Host discovery: quickly find which addresses on a subnet are alive without probing each by hand
Port scanning: tell open, closed and filtered ports apart, with several scan techniques to choose from
Service and version detection: goes beyond an open port to work out which program and version is listening
OS detection: guesses the target operating system from how it responds on the network
Scales up or down: scan one host or a network of hundreds of devices, tuning speed and stealth as needed
Zenmap GUI: ships with the installer, with scan profiles plus saved and comparable results
Script friendly: plenty of command line options and several output formats make it easy to automate
It is a command line tool, so it fits naturally into scripts you run on a schedule, and comparing two runs shows when someone quietly started a new service. Targets range from a single machine to hundreds of devices, and the response fingerprint lets it guess the remote operating system. If you prefer a GUI, the bundled Zenmap lets you pick scan profiles, save results and browse them by host and service.
Features
Host discovery: quickly find which addresses on a subnet are alive without probing each by hand
Port scanning: tell open, closed and filtered ports apart, with several scan techniques to choose from
Service and version detection: goes beyond an open port to work out which program and version is listening
OS detection: guesses the target operating system from how it responds on the network
Scales up or down: scan one host or a network of hundreds of devices, tuning speed and stealth as needed
Zenmap GUI: ships with the installer, with scan profiles plus saved and comparable results
Script friendly: plenty of command line options and several output formats make it easy to automate
