Nmap ("Network Mapper") is a free and open source utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Nmap uses raw IP packets in novel ways to determine what hosts are available on the network, what services (application name and version) those hosts are offering, what operating systems (and OS versions) they are running, what type of packet filters/firewalls are in use, and dozens of other characteristics. It was designed to rapidly scan large networks, but works fine against single hosts. Nmap runs on all major computer operating systems, and both console and graphical versions are available.
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great network utility. Useful for discover networks security holes. With the ZenMap GUI it is easy to use, much more than in the command line version. But also from GUI is possible to use all the same powerful scanning option. A must have
A must have for any IT worker, pentester etc.
i agree with that
Essential tool for networking / security. A must have for any IT worker, pentester etc.
this is the best portscanner there is . insecure.org publishes a cool list of the most popular security software tools also is a good exercise to go through them
Learning about security, and penetration testing? Start with nmap..
old school portscanning start here