Nmap (Network Mapper)

Nmap is an open source utility to explore the network and to audit the security tools. It scans large networks (even those consisting of hundreds of thousands of machines, claims one of the users) quite rapidly, although it works fine against single hosts. The users like the fact that Nmap uses raw IP packets to find out what hosts are available on the network, which application those hosts are offering and what operating systems (and what versions) they are running. It is able, state some of the readers, to indicate what type of packet filters and firewalls are in use. Nmap runs on most types of computers and both console and graphical versions are available.




What is very important and what is most frequently prized by the users – Nmap is free!

The scanner can be run to support most operating systems:
Linux, Windows, FreeBSD, OpenBSD, Solaris, IRIX, Mac OS X, HP-UX, NetBSD, Sun OS, Amiga.

Nmap offers many advanced features for power users. You can start out as simply as nmap -v- Atargethost. Both - command line and graphical (GUI) are available to suit user's preference. Those who do not wish to compile Nmap from source can always use the binaries. Although it is not so easy to run, Nmap has good, up-to-date man pages and tutorials in many languages.
The disadvantage noticed by the users is the fact that the scanner comes with no warranty.

The swiss army knife of network surveilance.What can i say,it should be in every networking professionals toolbox.Advantage is the prize,its free open source.Yet a very powerfull tool to gain more knowledge about the target.You have two versions,one for the command prompt and NmapFE as GUI interface.Drawback is the lack of an suitable report generator,although mostly one will use Nessus and Nmap together.
Free tool Nmap: the one I will always use and trust, most reliable for discovering and fingerpritng, the fastest one too. The main purpose of the tool to discover, to identify open ports or fingerprint services.
Nmap has won Information Security Product of the Year award by Linux Journal, Info World and Codetalker Digest.

Ratings show that Nmap is among the top ten (out of 30,000) programs at the Freshmeat.Net repository.

The result of an Nmap run is a list of scanned targets with some more information on each of them (depending on the options used),
which is quite useful according to our testers. In addition to the interesting ports table, Nmap can provide further details on targets, including reverse DNS names, operating system guesses, device types, and MAC addresses.