Nessus Vulnereability Scanner is one of the most powerful, popular and capable vulnerability scanners, particularly for UNIX or Windows systems. It was initially free and open source, but they closed the source code in 2005 and removed the free "Registered Feed" version in 2008. It now costs $1,200 per year, which still beats many of its competitors. A free “Home Feed” is also available, though it is limited and only licensed for home network use.
Nessus is constantly updated, with more than 46,000 plugins. Key features include remote and local (authenticated) security checks, a client/server architecture with a web-based interface, and an embedded scripting language for writing your own plugins or understanding the existing ones. Agentless auditing of configurations, patches, and web applications. 55,000+ vulnerability and configuration checks (plugins) – new plugins updated daily. Scans networks, systems, data, and applications. Post-scan analysis and monitoring tools. Part of Tenable's enterprise USM platform – providing centralized management of multiple vulnerability scanners and real-time vulnerability, log, and compliance management.
Download Here :: Nessus 5.2
Official Website :: http://www.tenable.com/products/nessus