Metasploit

This is the most popular cross-platform tool used today for penetration testing of the network. It has seven interfaces, among which Rapid 7 and Strategic Cyber LLC are the most popular. It allows users to identify various vulnerabilities in the system and take the required mitigation steps. Moreover, the Metasploit Framework can be extended to use add-ons in multiple languages.

Download link: http://www.metasploit.com/